Electrical Engineering - How much/what electrical danger performing on a covered stage during rain?

Author

How much/what electrical danger performing on a covered stage during rain?

HiC

2007-09-04, 3:25 am

I've heard of performers being electrocuted by a mic. If someone is
performing on a covered stage when it's raining - not necessarily with
lightning - or any other time for that matter - what should be
checked/in place to make sure there's no danger to the performer(s)?
(Other than not performing) Asked another way, what potentially COULD
create a dangerous situation that some flunkies involved with stage
operations/sound who don't know better might not check or just might
fall between the cracks even with pros?

If someone doesn't like to just assume "it's all taken care of" and
wants to be sure a loved one or friend who's performing is safe, who
should they typically talk to and what questions should they ask and
get clear answers to and/or what should they personally inspect?

Any other stage safety issues that experience has taught you to be
aware of?

Thanks for all input

David L. Jones

2007-09-04, 3:25 am

On Sep 4, 3:07 pm, HiC <brasspl...@yahoo.com> wrote:
> I've heard of performers being electrocuted by a mic. If someone is
> performing on a covered stage when it's raining - not necessarily with
> lightning - or any other time for that matter - what should be
> checked/in place to make sure there's no danger to the performer(s)?
> (Other than not performing) Asked another way, what potentially COULD
> create a dangerous situation that some flunkies involved with stage
> operations/sound who don't know better might not check or just might
> fall between the cracks even with pros?
>
> If someone doesn't like to just assume "it's all taken care of" and
> wants to be sure a loved one or friend who's performing is safe, who
> should they typically talk to and what questions should they ask and
> get clear answers to and/or what should they personally inspect?
>
> Any other stage safety issues that experience has taught you to be
> aware of?
>
> Thanks for all input

Using a wireless MIC seems like an obvious solution.

Also, turn the volume down, to prolong your hearing for a few more
years.
And I've heard that spilled beer can be a slip hazard on stage,
beware.

Dave.

Phil Allison

2007-09-04, 3:25 am

"HiC" <brassplyer@yahoo.com>

** All brass players are MORONS.

> I've heard of performers being electrocuted by a mic. If someone is
> performing on a covered stage when it's raining - not necessarily with
> lightning - or any other time for that matter - what should be
> checked/in place to make sure there's no danger to the performer(s)?
> (Other than not performing) Asked another way, what potentially COULD
> create a dangerous situation that some flunkies involved with stage
> operations/sound who don't know better might not check or just might
> fall between the cracks even with pros?

** When sound gear gets wet - it becomes lethal.

Some gear gets more lethal than others but YOU cannot which is which.

The ONLY safe move is to shut down all AC power and play acoustic.

........ Phil

Richard Crowley

2007-09-04, 3:25 am

"HiC" wrote ...
> I've heard of performers being electrocuted by a mic.

More likely the equipment that the mic is connected to.

I would bet that a guitar player is much more likely to
receive an electrical shock from an electric guitar amp
than from a PA system (via the microphone). PA systems
seem more likely to be properly grounded, etc. while guitar
amps are a much more unknown quantity (particularly old
"classic" ones.)

> If someone is performing on a covered stage when it's
> raining - not necessarily with lightning - or any other
> time for that matter - what should be checked/in place
> to make sure there's no danger to the performer(s)?

That is such a complex and open-ended question I
would think it would be irresponsible to try to create
some sort of comprehensive checklist. Especially for
something that could potentially be life-threatening.

OTOH, if the opening act doesn't get electrocuted,
would seem to be a better chance that the system
is at least somewhat "safe". :-)

> (Other than not performing) Asked another way,
> what potentially COULD create a dangerous situation
> that some flunkies involved with stage operations/sound
> who don't know better might not check or just might
> fall between the cracks even with pros?

There are certainly ways of measuring leakage current,
testing grounds, etc that play a role in ensuring that a
system is operating safely. But it generally isn't something
that a performer can do. You must rely on (and put your
life into the hands of) the operators of the systems.

> If someone doesn't like to just assume "it's all taken
> care of" and wants to be sure a loved one or friend
> who's performing is safe, who should they typically
> talk to and what questions should they ask and get
> clear answers to and/or what should they personally
> inspect?

I wouldn't perrform in the rain or if there was any water
on the stage, etc. It would appear that you are at the
mercy of the producer and his choice of competent
engineering for electrical / lighting / sound systems.

Joseph Ashwood

2007-09-04, 3:25 am

colin

2007-09-04, 9:25 am

Its not "usually" the sound system that creates the hazard
its the guitarist who has a groud fault or has snipped off the ground lug
from his power plug or is incorrectly using a edison adapter wo creates a
hazard condition
when his improperly grounded rig meets the right condition and a properly
grounded rig the current flows from his source(amp) out his guitar cable
into his guitar
now all he has to do is touch his strings and a mic stsand of a properly
grounded system toallow the current to complete its journey to ground
right through his body

"most" sound companies are accutly aware of proper electriacal protocol
most musicians are not
George

wildchildtiedyes

2007-09-04, 9:25 am

This is why GFI's are often required for any outside power.
bk
"HiC" <brassplyer@yahoo.com> wrote in message
news:1188882445.023703.183640@o80g2000hse.googlegroups.com...
> I've heard of performers being electrocuted by a mic. If someone is
> performing on a covered stage when it's raining - not necessarily with
> lightning - or any other time for that matter - what should be
> checked/in place to make sure there's no danger to the performer(s)?
> (Other than not performing) Asked another way, what potentially COULD
> create a dangerous situation that some flunkies involved with stage
> operations/sound who don't know better might not check or just might
> fall between the cracks even with pros?
>
> If someone doesn't like to just assume "it's all taken care of" and
> wants to be sure a loved one or friend who's performing is safe, who
> should they typically talk to and what questions should they ask and
> get clear answers to and/or what should they personally inspect?
>
> Any other stage safety issues that experience has taught you to be
> aware of?
>
>
> Thanks for all input
>

Phil Allison

2007-09-04, 9:25 am

"Fred Bloggs"
>
>
> It is absolutely essential that all the power circuits have Ground Fault
> Circuit Interrupter (GFCI) protection, and that these be tested during the
> initial installation. It's also a good idea to surge protect all the
> equipment plugged directly into the line.
>
> All of the handheld electricals should have a UL double insulation rating.

** Complete insanity !!!!

It is COLOSSALLY DANGEROUS to use a class 2 item after it has become
WET !!!

The Bloggs goon is a complete MORON !!

........ Phil

Scott Dorsey

2007-09-04, 9:25 am

In article <1188882445.023703.183640@o80g2000hse.googlegroups.com>,
HiC <brassplyer@yahoo.com> wrote:
>I've heard of performers being electrocuted by a mic. If someone is
>performing on a covered stage when it's raining - not necessarily with
>lightning - or any other time for that matter - what should be
>checked/in place to make sure there's no danger to the performer(s)?
>(Other than not performing) Asked another way, what potentially COULD
>create a dangerous situation that some flunkies involved with stage
>operations/sound who don't know better might not check or just might
>fall between the cracks even with pros?

The reason that this kind of thing happens is either because the ground
on the electrical power service is bad, and nobody has checked it, or
because somebody has specifically defeated the safety ground on some
piece of equipment.

A special case of the safety ground problem is the old guitar amp that
never was built with a safety ground, just a 2-pin plug. Some of those
are even hot chassis. You plug it in, and the chassis may be floating
way above ground, and when you pick up the guitar you are too. Touch
the grounded mike and you get a shock. These amps need to be fixed and
modern grounded cords installed on them.

>If someone doesn't like to just assume "it's all taken care of" and
>wants to be sure a loved one or friend who's performing is safe, who
>should they typically talk to and what questions should they ask and
>get clear answers to and/or what should they personally inspect?

Hire competent sound crew. If you ever, ever see a 3-to-2 prong
"cheater" or an cord with the ground lug lopped off, you are not dealing
with a competent crew and it is time to leave before someone gets hurt.
Look at the backline amps too.

If this is an outdoor festival, there is probably a seperate group of
people in charge of power distribution and management. Talk to them.

>Any other stage safety issues that experience has taught you to be
>aware of?

You mean like stage risers that collapse and injure people?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Mark

2007-09-04, 9:25 am

On Sep 4, 1:07 am, HiC <brasspl...@yahoo.com> wrote:
> I've heard of performers being electrocuted by a mic. If someone is
> performing on a covered stage when it's raining - not necessarily with
> lightning - or any other time for that matter - what should be
> checked/in place to make sure there's no danger to the performer(s)?
> (Other than not performing) Asked another way, what potentially COULD
> create a dangerous situation that some flunkies involved with stage
> operations/sound who don't know better might not check or just might
> fall between the cracks even with pros?
>
> If someone doesn't like to just assume "it's all taken care of" and
> wants to be sure a loved one or friend who's performing is safe, who
> should they typically talk to and what questions should they ask and
> get clear answers to and/or what should they personally inspect?
>
> Any other stage safety issues that experience has taught you to be
> aware of?
>
> Thanks for all input

best bet is a wireless mic.....if there are no wires attached to it,
you are basically totally safe.

next best bet, if you have to hold a wired mic, do not touch anything
else metal and do not have your feet wet.

if the mic should be live, you won't be shocked unless you touch
another metal object or you are grounded through wet feet...

if there is lightning around I would use ONLY a wireless mic.
touch nothing that is wired or connected to anything.

Mark

Scott Dorsey

2007-09-04, 9:25 am

colin <colin.rowe1@ntworld.NOSPAM.com> wrote:
>
>any mains powered electrical equipment operated in the rain
>is potentialy lethal unless it is sufficiently protected from water geting
>in.

Absolutely. This means putting the stage in a fairly well-protected tent
(which means lousy acoustics, sorry about that), double-insulating the power
system and covering all camlocks and junctions with plastic sheeting. It
means careful grounding, GFIs, and it means a power dispatcher who wanders
around with a meter checking ground fault currents so he has a good idea
when the leakage is getting to the point where a GFI may pop.

>it might not hurt if the microphone got wet,
>but if the amp it is connected to got wet ... fizzle hiss zap

It's easy to keep the equipment dry. But keeping the _people_ dry is the
hard part.

>do people still use mic cables much for anything larger than a pub
>performance ?

Sure, thousands and thousands of feet of the stuff. It just works, unlike
wireless systems.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

2007-09-04, 9:25 am

> if the mic should be live, you won't be shocked unless you touch
> another metal object or you are grounded through wet feet...

I all honesty I have not in 20 years of live sound seen a single"live mic"
I have experiacedproperly grounded mic when a "live" guitar player touches
the properly grounded mic
he get a shock
but its NOT THE MIC that has the juice
its the player
who is"live' AND THE CURRENT FLOWS TO GROUND THROUGH THE MIC
BUT THE mic does not SEND THE SHOCK TO THE PLAYER
gEOGRE

HiC

2007-09-04, 9:25 am

On Sep 4, 7:02 am, Chris Whealy <moc....@ylaehw.sirhc> wrote:

>
> If its tipping down with rain, would the audience still be there?
> Might be no need to perform in the first place.

For example, you can see the umbrellas in the audience and when you
see the shots from behind Bianca - who was the warmup act for Hall &
Oates, you can see it's coming down pretty good. Apparently the
performance was moved to this covered stage because of the weather.

http://youtube.com/watch?v=JLHZsauQsOY

She's using a wireless, even so, could there still be any other
potential hazards to her or others?

HiC

2007-09-04, 9:25 am

On Sep 4, 2:06 am, "Richard Crowley" <rcrow...@xp7rt.net> wrote:

> OTOH, if the opening act doesn't get electrocuted,
> would seem to be a better chance that the system
> is at least somewhat "safe". :-)

Unless of course, they ARE the opening act.

Phil Allison

2007-09-04, 9:25 am

"Fred Bloggs"
>
> There's no danger to the user of doubly insulated devices.

** That is CRIMINALLY INSANE BOLLOCKS !!!!!!!!!!

It is COLOSSALLY DANGEROUS to use a class 2 item after it has become
WET !!!

The Bloggs goon is a TOTAL MORON !!

........ Phil

Richard Crowley

2007-09-04, 9:25 am

"HiC" wrote ...
> "Richard Crowley" wrote:
>
>
> Unless of course, they ARE the opening act.

Sometimes you're the bug and sometimes you're
the windshield.

Deputy Dumbya Dawg

2007-09-04, 9:25 am

"HiC" <brassplyer@yahoo.com> wrote in message
news:1188882445.023703.183640@o80g2000hse.googlegroups.com...
> I've heard of performers being electrocuted by a mic. If
> someone is
> performing on a covered stage when it's raining - not
> necessarily with
> lightning - or any other time for that matter - what should
> be
> checked/in place to make sure there's no danger to the
> performer(s)?
> (Other than not performing) Asked another way, what
> potentially COULD
> create a dangerous situation that some flunkies involved
> with stage
> operations/sound who don't know better might not check or
> just might
> fall between the cracks even with pros?
>
> If someone doesn't like to just assume "it's all taken care
> of" and
> wants to be sure a loved one or friend who's performing is
> safe, who
> should they typically talk to and what questions should they
> ask and
> get clear answers to and/or what should they personally
> inspect?
>
> Any other stage safety issues that experience has taught you
> to be
> aware of?
>
>
> Thanks for all input

http://elvispelvis.com/electrocuted.htm

Keith Relf of the Yardbirds came back from the other side and
told me not to play my electric bass in the bathtub.
http://elvispelvis.com/electrocuted.htm

But if you are not sure and are standing on the stage with
your bass and a mic giving you the evil eye- or are wondering
about touching any other piece of electrified equipment and
just want to KNOW that when your lips touch the mic you will
not get bit here is a little something you can do that will
let you know the mic will not bite.

Consider this a last advice as a LAST RESORT if all the other
advice in the thread has been followed and you left your
voltmeter home but are still a little scared.

Let the inside of your forearm or the underside of your biceps
touch your guitar strings. The skin that is tender is the key
and if it is a little moisten even better. . Tender flesh will
be much more sensitive to a shock than say your calloused
finger tips and the moisture will assist the current flow if
it is possible and hence you will be more sensitive to a shock
situation. . Now part one of the connection is done. Now with
the SAME arm lick the back of your hand and touch that to the
mic or other suspect equipment.

This does three things.
1) the moist sensitive moist flesh sets up more ideal
conditions for current to flow if such potential exists. The
same effects are exhibited with wet lips and sweaty hands.

2) the current takes a safer path since it only goes through
your arm not your heart.

3) put your flesh in the path in such a way that if current
flows and you are shocked your body's natural tendency to
clench onto what is shocking you is avoided. Your hand may
make a fist if you do get shocked but touching the mic with
the back of your hand will make you pull away from the
shocking element and prevent you from clenching onto the mic
with one hand and the bass with the other until your internal
resistance gets really high ( you are cooked and smoldering).

No shock. Probably safe till someone changes something
somewhere.

peace
dawg

Dasvid McCall

2007-09-04, 1:25 pm

<tbmoas58@peoplepc.com> wrote in message
news:13dqmt13j5lmcc9@corp.supernews.com...
>
>
>
> I all honesty I have not in 20 years of live sound seen a single"live mic"
> I have experiacedproperly grounded mic when a "live" guitar player
> touches the properly grounded mic
> he get a shock
> but its NOT THE MIC that has the juice
> its the player
> who is"live' AND THE CURRENT FLOWS TO GROUND THROUGH THE MIC
> BUT THE mic does not SEND THE SHOCK TO THE PLAYER
> gEOGRE
Assuming that the sound system is properly grounded this is true.
The exception is the sound guy that had a ground loop that was
causing the system to hum no matter what he tries tio do, so he
removes the grounding on some items in the system to fix it.
A long as all of the equipment gets tied together by the shields,
and they find ground somewhere in the system, you should be OK.
But it is considered to be a very bad practise these days.

There was a time when nothing had a ground on it, and the AC
connectors weren't even polarized. Engineers doing any decent
sized instalation (radio stations for instance) would actually
design their grounding system and connect a wire to the chasis
of each piece of equipment and run that back to a common
ground that ultimately found it's way to an "earth ground" as in
a long copper clad stake driven into the directly into the dirt.
Everything had ballanced ins and outs and most of the cabling
inside the racks only had grounds connected at the input end to
allow the earth ground from having multiple paths.

When they started putting grounds on power plugs, the engineers
hated it because the additional ground connections screws up their
carefully designed grounding schemes. The first thing they did when
a new piece of equipment came in was gut the ground pin off of it.

I think it may even be illegal to remove the ground pins now.

David

Dasvid McCall

2007-09-04, 1:25 pm

"VWWall" <vwall@DEADearthlink.net> wrote in message
news:13dr1bad1vmagd3@corp.supernews.com...
> Dasvid McCall wrote:
> The next thing we did, particularly on a remote, was to "reverse the plug"
> to get rid of ground loop hum. Very few of the old units had "polarized"
> two blade plugs, and the "adapters" had an unpolarized two blade plug.
>
> Probably the only reason we didn't kill somebody was that there were few
> "musicians" plugged into high power amps!
>
> --
> Virg Wall, P.E. (One-time broadcast "engineer".)
>
Some guitar amps had a switch that allowed you to switch which side
of the line would be referenced to the chasis and shielding. It wasn't a
direct connection though, it went through a capacitor so the current was
limited to a trickle. After you connected everything up, you would try the
switch in both positions to see which side gave you the least hum.

David

Guy Macon

2007-09-04, 1:25 pm

Deputy Dumbya Dawg wrote:

>Consider this a last advice as a LAST RESORT if all the other
>advice in the thread has been followed and you left your
>voltmeter home but are still a little scared.
>
>Let the inside of your forearm or the underside of your biceps
>touch your guitar strings. The skin that is tender is the key
>and if it is a little moisten even better. . Tender flesh will
>be much more sensitive to a shock than say your calloused
>finger tips and the moisture will assist the current flow if
>it is possible and hence you will be more sensitive to a shock
>situation. . Now part one of the connection is done. Now with
>the SAME arm lick the back of your hand and touch that to the
>mic or other suspect equipment.
>
>This does three things.
>1) the moist sensitive moist flesh sets up more ideal
>conditions for current to flow if such potential exists. The
>same effects are exhibited with wet lips and sweaty hands.
>
>2) the current takes a safer path since it only goes through
>your arm not your heart.
>
>3) put your flesh in the path in such a way that if current
>flows and you are shocked your body's natural tendency to
>clench onto what is shocking you is avoided. Your hand may
>make a fist if you do get shocked but touching the mic with
>the back of your hand will make you pull away from the
>shocking element and prevent you from clenching onto the mic
>with one hand and the bass with the other until your internal
>resistance gets really high ( you are cooked and smoldering).
>
>No shock. Probably safe till someone changes something
>somewhere.

Before doing the above, touch the guitar strings to the
microphone. A guitarist I know was in the habit of doing
that, and one day a GFCI tripped during sound check.

--
Guy Macon
<http://www.guymacon.com/>

Scott Dorsey

2007-09-04, 1:25 pm

Dasvid McCall <mccallmail@verizon.net> wrote:
>The exception is the sound guy that had a ground loop that was
>causing the system to hum no matter what he tries tio do, so he
>removes the grounding on some items in the system to fix it.

We call these people "idiots" and "unsafe" and I have seen more than
one guy fired on the spot for doing precisely that. This is not
an acceptable behaviour.

We have plenty of iso boxes with 1:1 transformers that allow anyone
to break signal grounds at any point. Anyone that does an outdoor
festival without such things is not competent.

>A long as all of the equipment gets tied together by the shields,
>and they find ground somewhere in the system, you should be OK.
>But it is considered to be a very bad practise these days.

It has ALWAYS been considered to be very bad practice and you can NEVER
count on signal grounds providing a reliable safety earth. This is in
part because signal lines are always being moved around and someone may
briefly disconnect and repatch one. When you see a spark when you repatch
a cable, something very bad is happening and equipment is bound to get
damaged.

>There was a time when nothing had a ground on it, and the AC
>connectors weren't even polarized. Engineers doing any decent
>sized instalation (radio stations for instance) would actually
>design their grounding system and connect a wire to the chasis
>of each piece of equipment and run that back to a common
>ground that ultimately found it's way to an "earth ground" as in
>a long copper clad stake driven into the directly into the dirt.
>Everything had ballanced ins and outs and most of the cabling
>inside the racks only had grounds connected at the input end to
>allow the earth ground from having multiple paths.

And this can be a very reasonable configuration for a permanent installation
as long as EVERYONE recognizes the grounding scheme and follows it (and
that may require an orientation for new hires). It is not reasonable or
reliable in field operation, nor has it ever been acceptable in the field.

> When they started putting grounds on power plugs, the engineers
>hated it because the additional ground connections screws up their
>carefully designed grounding schemes. The first thing they did when
>a new piece of equipment came in was gut the ground pin off of it.
>
>I think it may even be illegal to remove the ground pins now.

It has been against the NEC here in the US, at least since the early seventies.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

David McCall

2007-09-04, 5:25 pm

"Scott Dorsey" <kludge@panix.com> wrote in message
news:fbk6ab$5d7$1@panix2.panix.com...
> Dasvid McCall <mccallmail@verizon.net> wrote:
>
> We call these people "idiots" and "unsafe" and I have seen more than
> one guy fired on the spot for doing precisely that. This is not
> an acceptable behaviour.
>
I'd agree with that.

> We have plenty of iso boxes with 1:1 transformers that allow anyone
> to break signal grounds at any point. Anyone that does an outdoor
> festival without such things is not competent.
>
Back when I was doing concert sound in the late 60s these things were
available, but not at all common.

>
> It has ALWAYS been considered to be very bad practice and you can NEVER
> count on signal grounds providing a reliable safety earth. This is in
> part because signal lines are always being moved around and someone may
> briefly disconnect and repatch one. When you see a spark when you repatch
> a cable, something very bad is happening and equipment is bound to get
> damaged.
>
I agree with that as well. Sparks and smoke are 2 things we are all better
off without.
Unless you live in GB where you depend on sparks to deal with your lights
:-)

>
> And this can be a very reasonable configuration for a permanent
> installation
> as long as EVERYONE recognizes the grounding scheme and follows it (and
> that may require an orientation for new hires). It is not reasonable or
> reliable in field operation, nor has it ever been acceptable in the field.
>
Yes, field equipment gets swapped around too much to use this approach,
but as you say, it is against regulations to remove grounds, which makes
grounding schemes in permanent racks more complicated than it was.

>
> It has been against the NEC here in the US, at least since the early
> seventies.
>
That sounds about right. I don't remember grounded outlets being very common
in the early 60s and don't remember any in the 50s. I still run into quite a
few
outlets with no ground even today. If you are lucky, the box will be
grounded and
you can just use an adapter. If the box isn't grounded, then I guess you
should
start looking for a water pipe.

David

> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

Benj

2007-09-04, 5:25 pm

<tbmoa...@peoplepc.com> wrote:

> I all honesty I have not in 20 years of live sound seen a single"live mic"
> I have experiaced properly grounded mic when a "live" guitar player touches
> the properly grounded mic
> he get a shock
> but its NOT THE MIC that has the juice
> its the player
> who is"live' AND THE CURRENT FLOWS TO GROUND THROUGH THE MIC
> BUT THE mic does not SEND THE SHOCK TO THE PLAYER

This may or not be true but can often happen.
Generally speaking as Scott notes the danger from gear on stage comes
from improper grounding. The use of clipped "ground buster" plugs and
the rest is a huge No-No. The whole idea of proper grounds is that IF
rain causes a short to say the mic stand, the fact that it is grounded
will simply blow the fuse rather than kill someone.

BUT the catch is that mics and sound systems are very prone to hum.
And soundmen tend to take a quick and easy approach to hum reduction.
"ground busting" is one such approach. Some gear even has ground-lift
switches built in! All this can work fine if you "bust" signal ground
and not safety ground. But obviously the potential for mistakes can be
great!

As for the above comments, they make sense too. Dig. A singer
typically also plays a guitar. The guitar plugs into an amp (often
"vintage" of unsafe design) on stage. The mic on the other hand is
feeding some professional gear run (presumably) by a pro. The
likelihood of the mic stand being soundly grounded is great. Thus, if
the guitar amp due to rain or other factors develops a voltage with
respect to earth ground, the guitar player touching the mic will
receive current not from the mic but from the faulty amp through his
guitar which flows out through the soundly grounded mic. Since it is
not common practice to run a heavy earth ground to the chassis of the
guitar amp on stage, there is a great potential for such an accident!

2007-09-04, 5:25 pm

"Benj" <bjacoby@iwaynet.net> wrote in message
news:1188935459.256519.50950@k79g2000hse.googlegroups.com...
>
> <tbmoa...@peoplepc.com> wrote:
>
>
> This may or not be true but can often happen.
> Generally speaking as Scott notes the danger from gear on stage comes
> from improper grounding. The use of clipped "ground buster" plugs and
> the rest is a huge No-No. The whole idea of proper grounds is that IF
> rain causes a short to say the mic stand, the fact that it is grounded
> will simply blow the fuse rather than kill someone.
>
> BUT the catch is that mics and sound systems are very prone to hum.
> And soundmen tend to take a quick and easy approach to hum reduction.
> "ground busting" is one such approach. Some gear even has ground-lift
> switches built in! All this can work fine if you "bust" signal ground
> and not safety ground. But obviously the potential for mistakes can be
> great!

Well, one of the first and most strict things I teach the soundguys that
work my shows is electrical saftey
IMO anyone who trys to cure a hum by defeating a saftey groung is simply a
idiot, not a "soundguy" , soundguys KNOW better
idiots dont

So IMO it may be symantics to you
but your not a soundguy unless you understand the job of a soundguy
and one of the most important aspects of that job is saftey
and electrical saftey is lesson one

Scott Dorsey

2007-09-04, 5:25 pm

David McCall <mccallmail@verizon.net> wrote:
>"Scott Dorsey" <kludge@panix.com> wrote in message
>Back when I was doing concert sound in the late 60s these things were
>available, but not at all common.

Part of that is because in the late 60s, everything was transformer-isolated
and there was already a transformer in the input and the output of the console
and on the input of the amp. So telescoping a ground was all you needed to
do to get transformer isolation.

These days transformers are too expensive and folks often consider them too
much of a source of possible audio degradation for everything to come with
transformer-isolation. So instead we have more iso boxes on the truck.

In the sixties, here in the US, if you knew someone that worked at the phone
company you could get them to bring you "repeat coils" which were used
for long distance circuit isolation and loading, and which were some of the
best audio transformers available at the time.

>That sounds about right. I don't remember grounded outlets being very common
>in the early 60s and don't remember any in the 50s. I still run into quite a
>few
>outlets with no ground even today. If you are lucky, the box will be
>grounded and
>you can just use an adapter. If the box isn't grounded, then I guess you
>should
>start looking for a water pipe.

In the US, you see a lot of those in homes, but not many left in commercial
locations. They turn up in old churches, though, as do things like DC
outlets...
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

mrdarrett@gmail.com

2007-09-04, 8:25 pm

On Sep 4, 5:08 am, <tbmoa...@peoplepc.com> wrote:
> Its not "usually" the sound system that creates the hazard
> its the guitarist who has a groud fault or has snipped off the ground lug
> from his power plug or is incorrectly using a edison adapter wo creates a
> hazard condition
> when his improperly grounded rig meets the right condition and a properly
> grounded rig the current flows from his source(amp) out his guitar cable
> into his guitar
> now all he has to do is touch his strings and a mic stsand of a properly
> grounded system toallow the current to complete its journey to ground
> right through his body
>
> "most" sound companies are accutly aware of proper electriacal protocol
> most musicians are not
> George

Exactly! I've worked around computers (not here in the USA) where a
ground was not available (a "special" adapter was used to remove the
ground... funny how those adapters are sold in stores), and it *hurts*
when you touch the chassis. 220V, too. We learned very quickly to
shut down the computers before plugging/unplugging devices, to avoid
pain.

Even when plugging my laptop into the mains to charge it, I'd get an
unpleasant shock if I even touched the ground around the microphone
Line Out jack.

Oh, here in the USA, the government really CARES about us! haha

Michael

David McCall

2007-09-04, 8:25 pm

"Scott Dorsey" <kludge@panix.com> wrote in message
news:fbkl41$9rj$1@panix2.panix.com...
>
> In the US, you see a lot of those in homes, but not many left in
> commercial
> locations. They turn up in old churches, though, as do things like DC
> outlets...
>
DC outlets? I've heard tell, but I've never actually seen one.
Do you know if you can you still buy DC and steam in New York?
DC is great for studios and theater because the lamps don't sing.
The problem is, there isn't much other than old resistance dimmers
that will work with DC. Have you seen it in other places?

David

> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

ChairmanOfTheBored

2007-09-04, 8:25 pm

On Mon, 03 Sep 2007 22:07:25 -0700, HiC <brassplyer@yahoo.com> wrote:

Snipped drivel...

Use wireless devices. Doh!

UltimatePatriot

2007-09-04, 8:25 pm

On Tue, 04 Sep 2007 06:09:16 -0700, Mark <makolber@yahoo.com> wrote:

>next best bet, if you have to hold a wired mic, do not touch anything
>else metal and do not have your feet wet.

Well, that pretty much rules out live stage performances in the rain
with a wired mic, eh?

Jeez!

David McCall

2007-09-04, 8:25 pm

<mrdarrett@gmail.com> wrote in message
news:1188945207.416963.248720@19g2000hsx.googlegroups.com...
>
> Exactly! I've worked around computers (not here in the USA) where a
> ground was not available (a "special" adapter was used to remove the
> ground... funny how those adapters are sold in stores), and it *hurts*
> when you touch the chassis. 220V, too. We learned very quickly to
> shut down the computers before plugging/unplugging devices, to avoid
> pain.
>
In the US, I've seen 2 types of adapters.

One has a 3 pronged outlet with a 2 prong plug and aw ground wire
that is intended to be connected to the screw that holds the plate on.
Assuming that there is a metal box, and it is grounded (big assumptions).
If everything goes as to plan, the 3 pronged outlet should then be fine.
The advantage of the wire is that you can use one in each outlet.
Some people just cut off the wires and ignore the ground (bad plan).

The other style is the same thing except with a spade attached directly
to the plug in such a position that it can be connected directly to the
screw to provide a ground and it locks the adapter onto the outlet
making it more stable. You can only use one on a duplex outlet.

If used correctly, these are fine tools, but using them to lift the ground
is not allowed.

> Even when plugging my laptop into the mains to charge it, I'd get an
> unpleasant shock if I even touched the ground around the microphone
> Line Out jack.
>
That isn't a situation that you should have to put up with.
Typically a laptop floats and isn't directly connected to ground.
There is probably something connected to it that isn't wired correctly,
or has some other fault. A while back, the RF cable for the cable TV
had quite a bit of kick when referenced to a water pipe ground.
We have fiber running directly to the side of the house now.
It is no longer an issue :-)

> Oh, here in the USA, the government really CARES about us! haha
>
They try, but you have to remember that some of "us" are retailers and
manufactures may have a different slant on what caring should be.
Sometimes they have more pull than you or I.

David

> Michael
>

Phil Allison

2007-09-04, 9:25 pm

"Christian Marg"

> Phil Allison wrote:
>
> Would you care to tell us why instead of insulting the original poster
> (which, in my opinion, is very unprofessional, as is "SHOUTING" in a
> news posting)?
>
> Maybe if you'd explain the danger of using a class 2 item, someone would
> listen to you?

** You have not read what I wrote & you do not know what an utter PITA
Bloggs is.

Try reading the user instructions and warnings for a class 2 audio
appliance.

Try explaining how a WET class 2 item of sound gear is still safe to
se - go on.

....... Phil

Scott Dorsey

2007-09-05, 3:25 am

David McCall <mccallmail@verizon.net> wrote:
>"Scott Dorsey" <kludge@panix.com> wrote in message
>DC outlets? I've heard tell, but I've never actually seen one.
>Do you know if you can you still buy DC and steam in New York?

NYC still had DC mains available until about a decade ago, when Con Edison
finally managed to install rectifier stacks running off three-phase at
the last of the DC customers. Most of them were folks using DC for elevator
service.

However, because of the leftover DC infrastructure, you will still see places
with DC power panels, operated off a rectifier, and with outlets off the DC
panel.

>DC is great for studios and theater because the lamps don't sing.
>The problem is, there isn't much other than old resistance dimmers
>that will work with DC. Have you seen it in other places?

It still turns up in some larger cities with very old infrastructure. Here
you're more likely to see DC elevator motors with a motor-generator set to
provide the DC for them, but up in Richmond, VA. there is a church with a
fancy speed control system on their organ that was originally hooked to DC
mains and today is run off a rectifier stack. There are probably a lot of
those around.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

wildchildtiedyes

2007-09-05, 3:25 am

I believe Boston Edison finally turned off its DC to the Back Bay area
around the late 80's.
When I was working in Boston around 1986, there were live 600V DC slate
boards in a few venues (Orpheum Theatre and Opera House to name a few) that
fed into the Boston MBTA. Tying in show power at the Orpheum used to
involve sitting, with my back up against the wall, and my head fitting just
below the slate board so that there wasn't any chance of it hitting any of
the live DC knife switches mounted just above me, while I tied in my tails
to the show power distro on the opposite wall.
Bruce
"Scott Dorsey" <kludge@panix.com> wrote in message
news:fbl57a$j1e$1@panix2.panix.com...
> David McCall <mccallmail@verizon.net> wrote:
>
> NYC still had DC mains available until about a decade ago, when Con Edison
> finally managed to install rectifier stacks running off three-phase at
> the last of the DC customers. Most of them were folks using DC for
> elevator
> service.
>
> However, because of the leftover DC infrastructure, you will still see
> places
> with DC power panels, operated off a rectifier, and with outlets off the
> DC
> panel.
>
>
> It still turns up in some larger cities with very old infrastructure.
> Here
> you're more likely to see DC elevator motors with a motor-generator set to
> provide the DC for them, but up in Richmond, VA. there is a church with a
> fancy speed control system on their organ that was originally hooked to DC
> mains and today is run off a rectifier stack. There are probably a lot of
> those around.
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

David Lesher

2007-09-05, 3:25 am

kludge@panix.com (Scott Dorsey) writes:

>Part of that is because in the late 60s, everything was transformer-isolated
>and there was already a transformer in the input and the output of the console
>and on the input of the amp. So telescoping a ground was all you needed to
>do to get transformer isolation.

Does anyone use 1:1 120v isolation transformers?

Doesn't folks plug EVERYTHING into a GFI? If the GFI is tripping,
You Have a Problem -- fix it.

Clearly what's needed is fiber-connected mikes, both vocal and
instrument...
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

BobG

2007-09-05, 3:25 am

The metal screen on an SM58 or SM57 is grounded. The guys that touch
the mic with the guitar strings all learned that if your lips hit the
mic grill, the whap that hits you in the face is like a big blue ball
of lightning, followed by little fireflys floating around for a few
more minutes while you get your senses back. It pretty much ruins the
whole set for me. What causes it is the stage backline is plugged into
a breaker box running off phase A, the lights are on phase B, and the
sound is on phase C, and they are all drawing different currents, so
the neutral is floating about 20V above ground because of the
unbalanced load. I can test a 9V battery by licking it, but 20V is
like a mule kick.

Stephen B.

2007-09-05, 3:25 am

"Scott Dorsey" <kludge@panix.com> wrote in message
news:fbl57a$j1e$1@panix2.panix.com...
> David McCall <mccallmail@verizon.net> wrote:
>
> NYC still had DC mains available until about a decade ago, when Con Edison
> finally managed to install rectifier stacks running off three-phase at
> the last of the DC customers. Most of them were folks using DC for
elevator
> service.

http://www.coned.com/sales/business/bus_elec.asp

Shows that the push to elimanate DC was still on in 2005. I think it is
still on going.
The Steam pipe that exploded over the summer was a Con Ed supply for
building uses. I have not heard of any efort to eliminat that service.

--
Stephen B.

Phil Allison

2007-09-05, 3:25 am

"BobG"
>
> The metal screen on an SM58 or SM57 is grounded. The guys that touch
> the mic with the guitar strings all learned that if your lips hit the
> mic grill, the whap that hits you in the face is like a big blue ball
> of lightning, followed by little fireflys floating around for a few
> more minutes while you get your senses back. It pretty much ruins the
> whole set for me.

** That sounds like copping the full 120 AC on the lips.

> What causes it is the stage backline is plugged into
> a breaker box running off phase A, the lights are on phase B, and the
> sound is on phase C, and they are all drawing different currents, so
> the neutral is floating about 20V above ground because of the
> unbalanced load.

** WTF has the neutral voltage got to do with it ?

Must be a VERY badly wired AC supply system for the safety ground on any
circuit to be more than 1 volt compared from the ground on any other.

Needs to be condemned.

........ Phil

2007-09-05, 9:25 am

"BobG" <bobgardner@aol.com> wrote in message
news:1188967086.670478.323850@d55g2000hsg.googlegroups.com...
> The metal screen on an SM58 or SM57 is grounded. The guys that touch
> the mic with the guitar strings all learned that if your lips hit the
> mic grill, the whap that hits you in the face is like a big blue ball
> of lightning, followed by little fireflys floating around for a few
> more minutes while you get your senses back. It pretty much ruins the
> whole set for me. What causes it is the stage backline is plugged into
> a breaker box running off phase A, the lights are on phase B, and the
> sound is on phase C, and they are all drawing different currents, so
> the neutral is floating about 20V above ground because of the
> unbalanced load. I can test a 9V battery by licking it, but 20V is
> like a mule kick.

simply not true
what causes it is a ground fault in the backline gear(99%) of the time
and the other % would be other fauklt conditiopns
there is nothing inherently unsafe in useing 3 phase power
george
>

2007-09-05, 9:25 am

what i find more than I care ton is some yahoo removes the 2 slot edisons
and replaces them with the grouded version , only there is no ground
connected on the back

every outlet get tested before it gets used
George

2007-09-05, 9:25 am

"ChairmanOfTheBored" <RUBored@crackasmile.org> wrote in message
news:krvrd3t3k5mv8167mu8npq6goleurg7q61@4ax.com...
> On Mon, 03 Sep 2007 22:07:25 -0700, HiC <brassplyer@yahoo.com> wrote:
>
> Snipped drivel...
>
>
> Use wireless devices. Doh!

like what? your cell phone?
here in the USA wireless micsare in turmoil because the government is
selling the bandwidth it exists on
george

Don Pearce

2007-09-05, 9:25 am

On Wed, 5 Sep 2007 06:57:03 -0400, <tbmoas58@peoplepc.com> wrote:

>
>"ChairmanOfTheBored" <RUBored@crackasmile.org> wrote in message
>news:krvrd3t3k5mv8167mu8npq6goleurg7q61@4ax.com...
>
>like what? your cell phone?
>here in the USA wireless micsare in turmoil because the government is
>selling the bandwidth it exists on
>george
>

In the uk the regulator (Ofcom) is preserving a chunk of UHF spectrum
from the digital switchover for wireless mics.

d

--
Pearce Consulting
http://www.pearce.uk.com

ChairmanOfTheBored

2007-09-05, 9:25 am

On Wed, 5 Sep 2007 06:57:03 -0400, <tbmoas58@peoplepc.com> wrote:

>
>"ChairmanOfTheBored" <RUBored@crackasmile.org> wrote in message
>news:krvrd3t3k5mv8167mu8npq6goleurg7q61@4ax.com...
>
>like what? your cell phone?
>here in the USA wireless micsare in turmoil because the government is
>selling the bandwidth it exists on
>george
>
Idiot. Live performers use wireless hooks EVERY DAY.

2007-09-05, 9:25 am

"ChairmanOfTheBored" <RUBored@crackasmile.org> wrote in message
news:b26td3tjtee9gqvhvm7fhgcnnbnmukv12h@4ax.com...
> On Wed, 5 Sep 2007 06:57:03 -0400, <tbmoas58@peoplepc.com> wrote:
>
> Idiot. Live performers use wireless hooks EVERY DAY.

you are so out of the loop no more debate can be had
tell me about the last time you set up 35 wireless mics for a show
I have

oh and while you at it can you name the protocol that will/is replaceing uhf
/vhf as a transmission mode?
put up or shut up
jerk

David Lesher

2007-09-05, 9:25 am

"Michael A. Terrell" <mike.terrell@earthlink.net> writes:

>David Lesher wrote:

[color=darkred]

[color=darkred]
> Sometimes the person is in contact with another current source and is
>killed by touching a grounded microphoe or instrument, so somone can die
>if the sysytem is properly installed. A GFI won't detect the current
>flow to earth from a different source.

Please note the word "EVERYTHING" above. Not some of the amps, one of the
mixers... everything on stage running from one GFI or another... [Except
the drummer, of course, who's likely running on crank, but at least he's
not a current source...]

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

2007-09-05, 9:25 am

"Romeo Rondeau" <schmuck_deluxe@fuggya.com> wrote in message
news:vlxDi.1234$7P7.598@newssvr19.news.prodigy.net...
> tbmoas58@peoplepc.com wrote:
>
> What do you think about Audio Technica's SpectraPulse?

I think its exciting also odd that it took 100 years to bring it to market
myself I will not buy or sell any more traditional wireless mics until this
bandwidth stuff settles
and I am down to just 6 in my inventory
but I hope to get some time to talk to the AT guys at AES
George

2007-09-05, 9:25 am

What causes it is the stage backline is plugged into[color=darkred]

I have not seen a show hooked up this way
with a single 3 phase hook up we put the sound INCLUDING stage and back line
on 1 leg and lights on the other two
bigger venues have several 3 phase disconnects
generall sound will take the smaller(200 amp or so) and lights will take the
larger(4-600 amps)
but still the backline is IME always on the same leg(s) as the sound
george

Scott Dorsey

2007-09-05, 9:25 am

David Lesher <wb8foz@panix.com> wrote:
>kludge@panix.com (Scott Dorsey) writes:
>
>
>Does anyone use 1:1 120v isolation transformers?

Sometimes, but the NEC in the US limits what you can do as far as breaking
safety grounds, when isolation transformers are in use. Normally folks use
isolation transformers only as low-pass filters, really.

>Doesn't folks plug EVERYTHING into a GFI? If the GFI is tripping,
>You Have a Problem -- fix it.

NEC says you have to use GFIs on most circuits outside, but not everyone
does. Personally, although GFIs are prone to falsing in high RFI environments,
I think they have saved more lives than they are given credit for.

>Clearly what's needed is fiber-connected mikes, both vocal and
>instrument...

Yes, but now you need to get power to the mike, as well, since the fibre
can't carry it. There are plenty of systems with fibre links between
the stage box and the console; you can see one at the National Gallery
of Art in their sculpture garden system. Plenty of isolation, and you
can run the skinny little fibre into an existing power conduit rather
than having to pull a big snake. Of course you now have to set the
console trims on the stage box which can be a pain without a big stage
crew.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey

2007-09-05, 9:25 am

BobG <bobgardner@aol.com> wrote:
>The metal screen on an SM58 or SM57 is grounded. The guys that touch
>the mic with the guitar strings all learned that if your lips hit the
>mic grill, the whap that hits you in the face is like a big blue ball
>of lightning, followed by little fireflys floating around for a few
>more minutes while you get your senses back. It pretty much ruins the
>whole set for me. What causes it is the stage backline is plugged into
>a breaker box running off phase A, the lights are on phase B, and the
>sound is on phase C, and they are all drawing different currents, so
>the neutral is floating about 20V above ground because of the
>unbalanced load. I can test a 9V battery by licking it, but 20V is
>like a mule kick.

This is a sign you got a BIG problem, not just with an unbalanced load,
but with poor neutral-ground bonding.

This is when it's time to walk offstage and cut your losses.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey

2007-09-05, 1:25 pm

<tbmoas58@peoplepc.com> wrote:
>"Romeo Rondeau" <schmuck_deluxe@fuggya.com> wrote in message
>
>I think its exciting also odd that it took 100 years to bring it to market
>myself I will not buy or sell any more traditional wireless mics until this
>bandwidth stuff settles
>and I am down to just 6 in my inventory
>but I hope to get some time to talk to the AT guys at AES

My worry is that with the spread spectrum systems, it's going to be much
harder to track down actual interference issues. The system degrades
very slowly as the channel bit rate goes down, until all of a sudden all
hell breaks loose and then where are you?

I am thinking the spread spectrum systems will be a godsend for smaller
installations, but they will be a nightmare for large events. With these
systems, you have to think about the devices adding broadband noise to a
wide channel... you can stack one on top of another on the same band, until
the overall noise floor of the wide channel reaches a certain point, and
then everything collapses.

And if something goes wrong you can't just pull up the spectrum analyzer
and pinpoint the offending source.

It's going to be interesting, but we're going to need new tools for
coordination and analysis before we can use them at big events, and
we don't have those tools yet. But creating those tools might be a
big moneymaker for someone.

The military has been doing this stuff since the seventies; it is a very
effective way to hide sources. As a consequence, they have put a lot of
time and effort at identifying and analyzing them... but a lot of that info
isn't public right now.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

PopMed

2007-09-05, 5:25 pm

On Sep 5, 10:29 am, klu...@panix.com (Scott Dorsey) wrote:
> Michael A. Terrell <mike.terr...@earthlink.net> wrote:
>
>
>
>
> Right. The GFI dectects only an imbalance in neutral and hot currents
> on the device it's protecting.
>
> This means that EVERYTHING on the stage area needs to be on a GFI, and
> that includes backline. If an amp is popping the GFI, you need to fix it.
>
> Now, I know that outdoor festivals it's very common to defeat GFIs in
> order to deal with backline equipment that has ground fault issues. I
> don't have a real problem with this, IF the power system grounds are
> good enough and the crew is watching out.
>
>
>
> Note that he was electrocuted by a circuit which BY LAW needs to be on
> a GFI, and has been for more than a decade now.
>
> See, in a perfect world, there are no electrical leakage issues. But
> the ground is there to protect you when things go wrong. And the GFI is
> there to protect you when the ground goes wrong. It's a belt-and-suspenders
> thing.
>
> Maybe you'll never need the ground to be there. Probably you'll never
> need the GFI. But if you SHOULD need it, you'll be really glad you have it.

Starting in the 60's I've enjoyed playing guitar and singing in
various garage bands. Nothing serious, loads of fun and we even made
a bit of money at it. I know this situation well: playing guitar
with the fingers of your left (fretting) hand wrapped around the neck
and strings and leaning into the mike to belt out the
chorus...Suddenly your lips brush against the metal wind screen of the
mike and you feel the jolt which hasn't killed you but now tells you
that this is going to be one of those "electrical evenings" with one
more thing to worry about other than harmonies, lyrics and timing!

Over the decades, I've noticed this phenomenon becoming much less
frequent and today it's virtually a non-issue. This of course is due
to the fact that nowadays everything is grounded. Even vintage gear
can be made safe such that no performer or tech should be in the
position of becoming the return path for two conductors that are at
significantly different potentials.

But what was the cause of this event? It was actually fairly common.
Every musician who played amplified instrument in the 60's and 70's
experienced it and very few of the amplifiers involved were actually
faulty.

I refer you to the schematic of a Fender Bassman model AA864
http://www.freeinfosociety.com/elec...view.php?id=859 This
model is an example of the type of amplifier used in the 60's for
everything from bass to organ to guitar and yes, vocals. It was
common practice (although not ideal) to run all instruments and mikes
off 2 to 4 instrument amplifiers all of which had non-grounded and non-
polarized power plugs. Even when you graduated to a real PA system
the amplifier's design looked basically the same. Note the primary
(mains) circuit of the power supply. No earth ground, no polarization
for the plug or accessory socket.

Note the .047mfd 600 vdc cap attached to the "ground switch". This
allowed you to switch the chassis ground through the capacitor to
either the hot or neutral side of the mains. Other amplifiers lacked
the switch but still had a cap of similar value hard wired to one side
of the mains. In practice, you flipped the switch or unplugged and
reversed the "polarity" of the the power cord to the position which
gave you the least hum. It is ironic that the "least hum" position
was sometimes the one where the cap was connected to the hot side.
For this reason or simply because the band couldn't care less about a
bit of hum during the quiet passages their was a good chance that one
or more chassis ground was actually connected through a cap to the hot
side.

Now the reactance of a .047 ufd capacitor at 60 Hz is 56.4 Kohm. If
shunted across 117 vac the resulting "leakage current" is 2.074 ma
definitely enough to feel as a shock but probably not enough to kill
you unless you had other medical issues. In fact it would not trip
most GFCIs. Unless you had very sweaty hands and very moist lips, the
actual current flowing from one "hot" amp through your body to another
"cold" amp would be considerably less especially when the second
series connected cap is taken into account. This is probably why most
of the aforementioned musicians of the 60's are still alive though
perhaps a bit impaired.

So what was the problem? Well consider what the consumer-grade
capacitors of that area were made of. Was it mylar or polypropylene
or polystyrene? Did Jimi Hendrix use a capo onstage? Well the
typical cap of that value and voltage rating was a paper/foil/wax
device. If you've ever taken one of these apart (which is easily
done), you'll appreciate how low-tech they were and how flimsy was the
paper barrier which could short reducing the reactance to ZERO. If
you were unlucky enough to be standing on wet ground or lying in a
bathtub or brushed up against a genuinely grounded PA system you could
be in for a really bad day!

Fortunately what I've described above was a rare event but I sure am
happy to use properly grounded gear so that I can concentrate on
harmonies, lyrics and timing!

David

BobG

2007-09-05, 5:25 pm

On Sep 5, 2:12 pm, "Paul Hovnanian P.E." <pa...@seanet.com> wrote:
> I've worked on a few old time guitar amps. IIRC, some Fender amps
> included a 'hum' switch that coupled the amp chassis to one side or the
> other of the line. I forget the value of the cap., but if anyone
> recalls, it would be interesting to see what sort of currents might pass
> from the hot side of the line, through the cap., a human body (Mick
> Jagger's tongue?), and another similar cap. in a second amp to the
> neutral side.
=================================
..047uf 600V as I recall.

PopMed

2007-09-05, 5:25 pm

On Sep 5, 2:12 pm, "Paul Hovnanian P.E." <pa...@seanet.com> wrote:
> BobG wrote:
>
>
> In a perfect world, all exposed metal should be tied to a non
> current-carrying grounding buss. Then the neutral can float wherever it
> wants.
>
> I've worked on a few old time guitar amps. IIRC, some Fender amps
> included a 'hum' switch that coupled the amp chassis to one side or the
> other of the line. I forget the value of the cap., but if anyone
> recalls, it would be interesting to see what sort of currents might pass
> from the hot side of the line, through the cap., a human body (Mick
> Jagger's tongue?), and another similar cap. in a second amp to the
> neutral side.
>
> Perhaps this is why all the British bands came over to the USA. 110V is
> more survivable than 220V. ;-)
>
I agree Paul. My other post addresses what you bring up. Sorry I
didn't see your post come in while I was typing mine. Interestingly
the British Marshall amps and others to my knowledge had no grounding
caps. Even back then the mains cords seemed to be grounded. I spent
some time in Sweden in the late 60's and met a hospital engineer who
absolutely could not believe how comparatively flimsy the US two prong
plug was. He thought they should be outlawed!

David

Arny Krueger

2007-09-05, 5:25 pm

"PopMed" <popmedkoh@gmail.com> wrote in message
news:1189022900.452520.4790@50g2000hsm.googlegroups.com...

> I spent
> some time in Sweden in the late 60's and met a hospital engineer who
> absolutely could not believe how comparatively flimsy the US two prong
> plug was. He thought they should be outlawed!

I felt that way the whole time I lived in Germany, and for several years
after I returned to the US. A minimal US 3-prong isn't all that wonderful,
either.

There has been some consciousness-raising among the designers of US
standards plugs since then, but AFAIK it isn't manditory.

David McCall

2007-09-05, 5:25 pm

"PopMed" <popmedkoh@gmail.com> wrote in message
news:1189021865.952501.156310@57g2000hsv.googlegroups.com...
>
> So what was the problem? Well consider what the consumer-grade
> capacitors of that area were made of. Was it mylar or polypropylene
> or polystyrene? Did Jimi Hendrix use a capo onstage? Well the
> typical cap of that value and voltage rating was a paper/foil/wax
> device. If you've ever taken one of these apart (which is easily
> done), you'll appreciate how low-tech they were and how flimsy was the
> paper barrier which could short reducing the reactance to ZERO. If
> you were unlucky enough to be standing on wet ground or lying in a
> bathtub or brushed up against a genuinely grounded PA system you could
> be in for a really bad day!
>
> Fortunately what I've described above was a rare event but I sure am
> happy to use properly grounded gear so that I can concentrate on
> harmonies, lyrics and timing!
>
Speaking of foil and paper caps.
In the late 50s I had the fun time of spending hours cleaning thousands of
little bits of gooey wax paper and foil out of the inside of a point to
point
wired Gibson tube guitar amp. This was the main filter in the power supply
and it faild with quite a bang. Good old days? Not always :-)

David

> David
>

Phil Allison

2007-09-05, 5:25 pm

"VWWall"
>
> That was probably not a paper cap, but an electrolytic, with considerable
> voltage across it. When they blew, the remains looked like a chicken had
> been plucked and the feathers left behind!
>
> They still blow, but most are now in aluminium cans, not a cardboard tube
> like the older ones.
>

** Nonsense.

Electro caps were then and still are now all fitted into aluminium cans,
then sealed at the top with a rubber gasket to prevent loss of the volatile
electrolyte. The can was connected to the negative terminal of the
capacitor and a wire lead welded to the closed end.

1950s and early 1960 examples were typically covered in cardboard tubes -
usually reddish brown in colour.

Later examples were fitted into plastic sleeves - could be nearly any
colour.

....... Phil

Rich Grise

2007-09-05, 5:25 pm

On Wed, 05 Sep 2007 16:12:10 -0400, Arny Krueger wrote:
> "PopMed" <popmedkoh@gmail.com> wrote in message
>
>
> I felt that way the whole time I lived in Germany, and for several years
> after I returned to the US. A minimal US 3-prong isn't all that wonderful,
> either.
>
> There has been some consciousness-raising among the designers of US
> standards plugs since then, but AFAIK it isn't manditory.

Ah, you yer-a-peein' guys are just jealous that we've got such an
inexpensive, convenient, universally-recognized plug as the US standard,
that's been in service reliably for over a half-century.

Admittedly, the contact interface isn't intended to support large weights,
merely to conduct electricity. :-)

But really, do you Brits and other Yurps need a fist-sized plug just so
you don't have to remember to keep your thumb out from between the prongs?

Thanks!
Rich

Scott Dorsey

2007-09-05, 8:25 pm

PopMed <popmedkoh@gmail.com> wrote:
>So what was the problem? Well consider what the consumer-grade
>capacitors of that area were made of. Was it mylar or polypropylene
>or polystyrene? Did Jimi Hendrix use a capo onstage? Well the
>typical cap of that value and voltage rating was a paper/foil/wax
>device. If you've ever taken one of these apart (which is easily
>done), you'll appreciate how low-tech they were and how flimsy was the
>paper barrier which could short reducing the reactance to ZERO. If
>you were unlucky enough to be standing on wet ground or lying in a
>bathtub or brushed up against a genuinely grounded PA system you could
>be in for a really bad day!

Doesn't even need to be that bad! Take a .47 uF cap, and even the
impedance at 60 Hz is low enough to allow a good fault current.

You'll see fault currents on some cheap PC power supplies with pi
filters on the inputs... the pi filter leakage is high enough to
pop the GFI. So what do power supply manufacturers do when people
complain about this? They leave off the filtration entirely and spew
trash on the power line.

But that is a rant for another day.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey

2007-09-05, 8:25 pm

Rich Grise <rich@example.net> wrote:
>On Wed, 05 Sep 2007 16:12:10 -0400, Arny Krueger wrote:
>
>Ah, you yer-a-peein' guys are just jealous that we've got such an
>inexpensive, convenient, universally-recognized plug as the US standard,
>that's been in service reliably for over a half-century.
>
>Admittedly, the contact interface isn't intended to support large weights,
>merely to conduct electricity. :-)

I got one word for you: NEMA Twist-Locks. Available from 15A on up.
They make the Europlug look cheap and flimsy!
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Phil Allison

2007-09-05, 8:25 pm

"VWWall"
Phil Allison wrote:
>
>
> I have in my hands a red, yellow, and blue one. The can is much thinner
> than the recent electrolytics which use the can as a mount.

** Oh - SOOOO now they DO have an aluminium can ??

Musta been hiding inside that gaudy cardboard - eh ??

> The accepted sig for ng's is: (2 dashes, space, line return)

** BOLLOCKS !!

Why don't you go and FUCK yourself

- you posturing, bullshitting XXXXXXX !!.

....... Phil

ChairmanOfTheBored

2007-09-05, 8:25 pm

On Wed, 5 Sep 2007 08:11:23 -0400, <tbmoas58@peoplepc.com> wrote:

>
>"ChairmanOfTheBored" <RUBored@crackasmile.org> wrote in message
>news:b26td3tjtee9gqvhvm7fhgcnnbnmukv12h@4ax.com...
>
>you are so out of the loop no more debate can be had

You're a goddamned idiot, and you couldn't debate if your life depended
on it, twit.

>tell me about the last time you set up 35 wireless mics for a show
>I have

I wouldn't work "a show you have". Your shows are shit. I have,
however made wireless mic systems that pass voice, video and data over
VARIOUS bands.

Some are used by LEOs. Some are used on carrier decks.

Do you even know what a diversity receiver is?

>oh and while you at it can you name the protocol that will/is replaceing uhf
>/vhf as a transmission mode?

You're an idiot. The devices I mentioned are using a proprietary
packet model, and it utilizes QAM 256.

>put up or shut up

You're an idiot.

>jerk

Thanks for proving the above assertion.
>
Fuck off, you ten years behind the curve retard.

http://www.avalonrf.com/Products/transmitters.html

ChairmanOfTheBored

2007-09-05, 8:25 pm

On Wed, 05 Sep 2007 07:32:34 -0500, Romeo Rondeau
<schmuck_deluxe@fuggya.com> wrote:

>tbmoas58@peoplepc.com wrote:
>
>What do you think about Audio Technica's SpectraPulse?

You could have at least provided ONE link, dingledorf.

http://www.indoorlbs.com/id586.html

Phil Allison

2007-09-05, 8:25 pm

"Chairman Of The Most Asinine Fuckwits "

>
>tbmoas58@peoplepc.com> wrote:
>
> You're a goddamned idiot, and you couldn't debate if your life depended
> on it, twit.
>
>
> I wouldn't work "a show you have". Your shows are shit. I have,
> however made wireless mic systems that pass voice, video and data over
> VARIOUS bands.
>
> Some are used by LEOs. Some are used on carrier decks.

** The police and onboard Navy vessels ??

Hardly the same category as stage performers.

> Do you even know what a diversity receiver is?

** This criminal MORON does not even know what a performer's " radio mic"
system is.

>
> You're an idiot. The devices I mentioned are using a proprietary
> packet model, and it utilizes QAM 256.

** Shame none of it is suitable for nor allowed to be used by performers.

> Thanks for proving the above assertion.
> Fuck off, you ten years behind the curve retard.
>
> http://www.avalonrf.com/Products/transmitters.html

** ROTFLMAO !!

No performance quality radio mics there at all !!

........ Phil

ChairmanOfTheBored

2007-09-06, 3:25 am

On Thu, 6 Sep 2007 10:51:33 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

> ** The police and onboard Navy vessels ??
>
> Hardly the same category as stage performers.
>

The ruggedized devices I spoke of have BETTER audio, video and data
figures than commercial crap does.

ChairmanOfTheBored

2007-09-06, 3:25 am

On Thu, 6 Sep 2007 10:51:33 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

>
>** This criminal MORON does not even know what a performer's " radio mic"
>system is.

You're a goddamned retard.

ChairmanOfTheBored

2007-09-06, 3:25 am

On Thu, 6 Sep 2007 10:51:33 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

>
>** Shame none of it is suitable for nor allowed to be used by performers.
>

Bullshit, asswipe. Every one of them are in legal public bands, IDIOT!

ChairmanOfTheBored

2007-09-06, 3:25 am

On Thu, 6 Sep 2007 10:51:33 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

>
>** ROTFLMAO !!
>
>No performance quality radio mics there at all !!
>

They can accept ANY mic, including professional audio.

Grow the fuck up, AlliTard.

Phil Allison

2007-09-06, 3:25 am

"Chairman Of The Lying Autistic MORONS "

>
> The ruggedized devices I spoke of have BETTER audio, video and data
> figures than commercial crap does.

** IRRELEVANT BULLSHIT !!

....... Phil

Phil Allison

2007-09-06, 3:25 am

"Chairman Of The Lying Autistic MORONS "

"Phil Allison"

>

[color=darkred]
> You're a goddamned retard.

** LOL

Dead donkeys have higher IQs than this sub human POS.

......... Phil

Phil Allison

2007-09-06, 3:25 am

"Chairman Of The Lying Autistic MORONS "

"Phil Allison"

>
>
> Bullshit, asswipe.

** Ridiculous lie.

........ Phil

Phil Allison

2007-09-06, 3:25 am

"Chairman Of The Lying Autistic MORONS "

>
> They can accept ANY mic, including professional audio.

** Not usable by music performers - at all.

YOU INSANE STINKING LIAR !!!!!!

......... Phil

Scott Dorsey

2007-09-06, 9:25 am

ChairmanOfTheBored <RUBored@crackasmile.org> wrote:
>On Thu, 6 Sep 2007 10:51:33 +1000, "Phil Allison"
><philallison@tpg.com.au> wrote:
>
>
> They can accept ANY mic, including professional audio.
>
> Grow the fuck up, AlliTard.

Wow, and this thread isn't even crossposed to rec.audio.opinion either.
It sure went downhill fast considering the Newsgroups: list.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey

2007-09-06, 9:25 am

David McCall writes:
> DC outlets? I've heard tell, but I've never actually seen one.
> Do you know if you can you still buy DC and steam in New York?
> DC is great for studios and theater because the lamps don't sing.
> The problem is, there isn't much other than old resistance dimmers
> that will work with DC. Have you seen it in other places?

Coincidentally, I just saw the following web citation:
http://www.nypost.com/seven/0905200...o_ko_its_dc.htm
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Martin Griffith

2007-09-06, 9:25 am

On Wed, 05 Sep 2007 17:24:55 -0700, in sci.electronics.design
ChairmanOfTheBored <RUBored@crackasmile.org> wrote:

>On Wed, 5 Sep 2007 08:11:23 -0400, <tbmoas58@peoplepc.com> wrote:
>
>
> You're a goddamned idiot, and you couldn't debate if your life depended
>on it, twit.
>
>
> I wouldn't work "a show you have". Your shows are shit. I have,
>however made wireless mic systems that pass voice, video and data over
>VARIOUS bands.
>
> Some are used by LEOs. Some are used on carrier decks.
>
> Do you even know what a diversity receiver is?
>
>
> You're an idiot. The devices I mentioned are using a proprietary
>packet model, and it utilizes QAM 256.
>
>
>
> You're an idiot.
>
>
> Thanks for proving the above assertion.
> Fuck off, you ten years behind the curve retard.
>
>http://www.avalonrf.com/Products/transmitters.html

Wow, what horrible bits of kit those are. They look as if they are
made in N Korea.

These are what professionals use
http://www.lectrosonics.com/wireless/wireless.htm

Martin

Camel

2007-09-06, 1:25 pm

Your engineers cut the grounds off the plugs ?????
Glad i don't work with those engineers!!

A proper design will factor in the use of current as well as older
style equiptment (which would include the recomended plug style)

Current equiptment requires the upgrade of all lines & such and
therefore - in this world of 3-prong plugs - design has changed.

I can only hope that your engineers have stopped cutting the saftey
factor from your equiptment.

On Sep 4, 9:19 am, VWWall <vw...@DEADearthlink.net> wrote:
> Dasvid McCall wrote:
>
>
> The next thing we did, particularly on a remote, was to "reverse the
> plug" to get rid of ground loop hum. Very few of the old units had
> "polarized" two blade plugs, and the "adapters" had an unpolarized two
> blade plug.
>
> Probably the only reason we didn't kill somebody was that there were few
> "musicians" plugged into high power amps!
>
> --
> Virg Wall, P.E. (One-time broadcast "engineer".)

David McCall

2007-09-06, 1:25 pm

"Camel" <elmasry75@gmail.com> wrote in message
news:1189091643.191340.227470@y42g2000hsy.googlegroups.com...
> Your engineers cut the grounds off the plugs ?????
> Glad i don't work with those engineers!!
>
> A proper design will factor in the use of current as well as older
> style equiptment (which would include the recomended plug style)
>
> Current equiptment requires the upgrade of all lines & such and
> therefore - in this world of 3-prong plugs - design has changed.
>
> I can only hope that your engineers have stopped cutting the saftey
> factor from your equiptment.
>
We're talking early 60s and these guys were a lot older than I was,
so I'll bet they stopped by now (probably stopped for good by now).

Everything was grounded separately in a carefully designed scheme
to eliminate ground loops, just not with the power cord.

David

David McCall

2007-09-06, 1:25 pm

"Scott Dorsey" <kludge@panix.com> wrote in message
news:fbovq0$hf8$1@panix2.panix.com...
>
> David McCall writes:
>
> Coincidentally, I just saw the following web citation:
> http://www.nypost.com/seven/0905200...o_ko_its_dc.htm
>
Thanks Scott. I wonder who the 5 remaining customers were.

> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

2007-09-06, 1:25 pm

In rec.audio.pro Joseph Ashwood <ashwood@msn.com> wrote:
> "HiC" <brassplyer@yahoo.com> wrote in message
> news:1188882445.023703.183640@o80g2000hse.googlegroups.com...
>
>
> For the most paranoid, see all those cables? They contain electricity.
>
> It is the volts that hurt, but the amps that kill. A phantom powered
> microphone should not have much in the way of amperage, worst case, go
> wireless they simply don't have the power to begin with. the real concern
> really is every amplifier, every speaker, every speaker cable, it only takes
> half an amp to kill a human,

It takes a lot less than that - .05A across the heart can kill you,
and .1A across the heart will most likely cause destructive ventricular
fibrillation.

--
Aaron

David Lee

2007-09-06, 8:25 pm

John XXXXXXXXon wrote...
> For what it's worth, In Europe, a ground fault protection device *must* trigger at no more than 30
> milliamps after no more than 30 milliseconds.
> There are`also rules about regular testing of fixed installations, & for testing temporary
> installations before first use.

Actually RCDs are available with tripping currents of 10, 30, 100 & 300mA and in time delayed
versions. That's only from the MK "Sentry" catalogue - there are probably others available as well.

David

Matthew Beasley

2007-09-06, 8:25 pm

"Scott Dorsey" <kludge@panix.com> wrote in message
news:fbnbpf$pdc$1@panix2.panix.com...
> Rich Grise <rich@example.net> wrote:

>
> I got one word for you: NEMA Twist-Locks. Available from 15A on up.
> They make the Europlug look cheap and flimsy!
> --scott
>

Maybe the europlug, but not the BS plug. That thing looks like it belongs
on a clothes dryer, not small appliances.

ChairmanOfTheBored

2007-09-06, 8:25 pm

On Thu, 06 Sep 2007 15:37:59 +0200, Martin Griffith
<mart_in_medina@ya___.es> wrote:

>
>Wow, what horrible bits of kit those are.

"bits of kit"

Get some language in your life, retard.

No, sorry chump. Rugged gear does not EVER look like it is made
overseas.

What a sorry bit of kit god gave you for a brain.

ChairmanOfTheBored

2007-09-06, 8:25 pm

On Thu, 06 Sep 2007 15:37:59 +0200, Martin Griffith
<mart_in_medina@ya___.es> wrote:

>These are what professionals use
>http://www.lectrosonics.com/wireless/wireless.htm
>

Lame. And you apparently do not know what the word professional means
either.