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Arc-Fault Interuptor Breakers
|
|
| Randell Tarin 2007-04-18, 1:25 pm |
| I'm finishing the construction of a master bedroom add-on to our home.
All the plugs in the room are on a single circuit on a 15-amp arc fault
breaker. Everything appears functional, but during cleanup, whenever I
connect my 7 AMP shop vac to the circuit, it kicks the breaker.
I noticed a similar occurance with a 20 GFI breaker when I attempted to
run an air compressor from it.
I have no problem with either power tool when running them from a
straight 20 AMP circuit.
What's happening here? Are protection breakers just that much more
sensitive?
TIA
Randell Tarin
| |
| Beachcomber 2007-04-18, 1:25 pm |
|
>I'm finishing the construction of a master bedroom add-on to our home.
>All the plugs in the room are on a single circuit on a 15-amp arc fault
>breaker. Everything appears functional, but during cleanup, whenever I
>connect my 7 AMP shop vac to the circuit, it kicks the breaker.
>
>I noticed a similar occurance with a 20 GFI breaker when I attempted to
>run an air compressor from it.
>
>I have no problem with either power tool when running them from a
>straight 20 AMP circuit.
>
>What's happening here? Are protection breakers just that much more
>sensitive?
>
It is probable that your appliances have universal (AC-DC) motors with
brushes, thus producing sparks and all sorts of voltage transients on
the line. This is what the arc-fault detectors are designed to detect
I guess this means I can no longer run my Tesla coil in my bedroom...
Bummer. :>
Beachcomber
| |
| Randell Tarin 2007-04-19, 9:25 am |
| Beachcomber wrote:
>
>
> It is probable that your appliances have universal (AC-DC) motors with
> brushes, thus producing sparks and all sorts of voltage transients on
> the line. This is what the arc-fault detectors are designed to detect
>
> I guess this means I can no longer run my Tesla coil in my bedroom...
> Bummer. :>
>
> Beachcomber
>
>
What about vacuum cleaners and hair dryers, both appliances typically
used in a bedroom? Well, I do have a 100 ft. extention cord...
| |
|
| Randell Tarin wrote:
> Beachcomber wrote:
>
> What about vacuum cleaners and hair dryers, both appliances typically
> used in a bedroom? Well, I do have a 100 ft. extention cord...
A GFCI trip suggests the air compressor has hot-to-ground leakage.
Brush motors are not supposed to trip AFCIs. AFCIs almost always include
a 30 mA ground fault trip (GFCIs use 5 mA). It is possible the shop vac
has hot-to-ground leakage. If you plug the shop vac into the GFCI does
it trip? Do you have more than 1 AFCI - trip the others also?
--
bud--
| |
| phil-news-nospam@ipal.net 2007-04-19, 1:25 pm |
| On Thu, 19 Apr 2007 08:34:21 -0500 Bud-- <remove.BudNews@isp.com> wrote:
| A GFCI trip suggests the air compressor has hot-to-ground leakage.
Or it could have neutral to ground leakage. If the neutral and ground
are connected together at the load, the return current will split between
those wires, and the GFCI will not see the same current level between hot
and neutral. In either case, the compressor is defective and dangerous
for use. It needs to be repaired or replaced.
| Brush motors are not supposed to trip AFCIs. AFCIs almost always include
| a 30 mA ground fault trip (GFCIs use 5 mA). It is possible the shop vac
| has hot-to-ground leakage. If you plug the shop vac into the GFCI does
| it trip? Do you have more than 1 AFCI - trip the others also?
There is a history of some AFCIs being overly sensitive, or some motor
loads having excess brush arcing, and tripping AFCIs (and not GFCIs).
The OP should test the shop vac on a GFCI. If it is OK on a GFCI, then
the AFCI should be returned to the manufacturer for evaluation (but they
will likely also need more information to reproduce the problem, if not
the actual shop vac). And the shop vac could be defective and have a
kind of fault, or excessive arcing, that the AFCI should detect.
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-04-19-0957@ipal.net |
|------------------------------------/-------------------------------------|
| |
| gfretwell@aol.com 2007-04-19, 5:25 pm |
| On 19 Apr 2007 15:04:59 GMT, phil-news-nospam@ipal.net wrote:
>On Thu, 19 Apr 2007 08:34:21 -0500 Bud-- <remove.BudNews@isp.com> wrote:
>
>| A GFCI trip suggests the air compressor has hot-to-ground leakage.
>
>Or it could have neutral to ground leakage. If the neutral and ground
>are connected together at the load, the return current will split between
>those wires, and the GFCI will not see the same current level between hot
>and neutral. In either case, the compressor is defective and dangerous
>for use. It needs to be repaired or replaced.
>
>
>| Brush motors are not supposed to trip AFCIs. AFCIs almost always include
>| a 30 mA ground fault trip (GFCIs use 5 mA). It is possible the shop vac
>| has hot-to-ground leakage. If you plug the shop vac into the GFCI does
>| it trip? Do you have more than 1 AFCI - trip the others also?
>
>There is a history of some AFCIs being overly sensitive, or some motor
>loads having excess brush arcing, and tripping AFCIs (and not GFCIs).
>The OP should test the shop vac on a GFCI. If it is OK on a GFCI, then
>the AFCI should be returned to the manufacturer for evaluation (but they
>will likely also need more information to reproduce the problem, if not
>the actual shop vac). And the shop vac could be defective and have a
>kind of fault, or excessive arcing, that the AFCI should detect.
Most AFCI trips get traced back to ground/neutral faults. That is
where the ceiling fans got that bad reputation. It was usually that
big cludge wirenut vibrating into the hickey when the fan was running.
The original AFCI designs (for the arc fault part) were only looking
for short duration current spikes in the 70a+ range. They just detect
dead shorts from line to neutral. The GFCI protection was added to
find shorts from neutral or line to ground at the 30ma level.
| |
| Randell Tarin 2007-04-19, 5:25 pm |
| gfretwell@aol.com wrote:
> On 19 Apr 2007 15:04:59 GMT, phil-news-nospam@ipal.net wrote:
>
>
>
>
>
> Most AFCI trips get traced back to ground/neutral faults. That is
> where the ceiling fans got that bad reputation. It was usually that
> big cludge wirenut vibrating into the hickey when the fan was running.
> The original AFCI designs (for the arc fault part) were only looking
> for short duration current spikes in the 70a+ range. They just detect
> dead shorts from line to neutral. The GFCI protection was added to
> find shorts from neutral or line to ground at the 30ma level.
It's very likely the fault of the shop-vac. I ran the vacuum and a hair
dryer without incident. It's on it's last leg and ready for
replacement anyway.
Thanks guys.
| |
| phil-news-nospam@ipal.net 2007-04-19, 8:25 pm |
| On Thu, 19 Apr 2007 16:12:34 -0400 gfretwell@aol.com wrote:
| On 19 Apr 2007 15:04:59 GMT, phil-news-nospam@ipal.net wrote:
|
|>On Thu, 19 Apr 2007 08:34:21 -0500 Bud-- <remove.BudNews@isp.com> wrote:
|>
|>| A GFCI trip suggests the air compressor has hot-to-ground leakage.
|>
|>Or it could have neutral to ground leakage. If the neutral and ground
|>are connected together at the load, the return current will split between
|>those wires, and the GFCI will not see the same current level between hot
|>and neutral. In either case, the compressor is defective and dangerous
|>for use. It needs to be repaired or replaced.
|>
|>
|>| Brush motors are not supposed to trip AFCIs. AFCIs almost always include
|>| a 30 mA ground fault trip (GFCIs use 5 mA). It is possible the shop vac
|>| has hot-to-ground leakage. If you plug the shop vac into the GFCI does
|>| it trip? Do you have more than 1 AFCI - trip the others also?
|>
|>There is a history of some AFCIs being overly sensitive, or some motor
|>loads having excess brush arcing, and tripping AFCIs (and not GFCIs).
|>The OP should test the shop vac on a GFCI. If it is OK on a GFCI, then
|>the AFCI should be returned to the manufacturer for evaluation (but they
|>will likely also need more information to reproduce the problem, if not
|>the actual shop vac). And the shop vac could be defective and have a
|>kind of fault, or excessive arcing, that the AFCI should detect.
|
|
| Most AFCI trips get traced back to ground/neutral faults. That is
| where the ceiling fans got that bad reputation. It was usually that
| big cludge wirenut vibrating into the hickey when the fan was running.
| The original AFCI designs (for the arc fault part) were only looking
| for short duration current spikes in the 70a+ range. They just detect
| dead shorts from line to neutral. The GFCI protection was added to
| find shorts from neutral or line to ground at the 30ma level.
That's not what some aspects of what I read say. There have been documents
(I didn't keep them handy) that described "series arcs" as arcs due to a
loose connection that isn't a short circuit path. The arc transients would
therefore have no more increase than what the load is, plus or minus any
circuit/load reactive components affecting it.
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-04-19-2003@ipal.net |
|------------------------------------/-------------------------------------|
| |
| gfretwell@aol.com 2007-04-19, 9:25 pm |
| On 20 Apr 2007 01:04:47 GMT, phil-news-nospam@ipal.net wrote:
>| Most AFCI trips get traced back to ground/neutral faults. That is
>| where the ceiling fans got that bad reputation. It was usually that
>| big cludge wirenut vibrating into the hickey when the fan was running.
>| The original AFCI designs (for the arc fault part) were only looking
>| for short duration current spikes in the 70a+ range. They just detect
>| dead shorts from line to neutral. The GFCI protection was added to
>| find shorts from neutral or line to ground at the 30ma level.
>
>That's not what some aspects of what I read say. There have been documents
>(I didn't keep them handy) that described "series arcs" as arcs due to a
>loose connection that isn't a short circuit path. The arc transients would
>therefore have no more increase than what the load is, plus or minus any
>circuit/load reactive components affecting it.
>
>--
There are not any "series arc" detectors out there yet., Siemens is
bragging about having one but it isn't really for sale.
The "combination" AFCI refers to being able to detect parallel arcs in
the wall plus an arc in a line cord. It is a lower level of current
detection when looking at a potential arc.
| |
|
| gfretwell@aol.com wrote:
> On 20 Apr 2007 01:04:47 GMT, phil-news-nospam@ipal.net wrote:
>
>
>
>
> There are not any "series arc" detectors out there yet., Siemens is
> bragging about having one but it isn't really for sale.
> The "combination" AFCI refers to being able to detect parallel arcs in
> the wall plus an arc in a line cord. It is a lower level of current
> detection when looking at a potential arc.
>
A interesting source of information on AFCIs is:
http://www.iaei.org/subscriber/maga..._gregmanche.htm
from IAEI News, January/February 2003,The Truth About AFCIs (Part 1)
(part 2 is at)
http://www.iaei.org/subscriber/maga..._gregmanche.htm
(and a response to reader comments)
http://www.iaei.org/subscriber/maga...03d_gregory.htm
The currently required "Branch/feeder" AFCIs are required to detect 75A
arcs. That will detect parallel arcs, but not series arcs.
"Outlet circuit" AFCIs are required to detect 5A arcs, which will detect
series and parallel arcs.
The "Combination" AFCIs required by the NEC on 1-1-08 combine "Outlet
circuit" and "Branch/feeder" requirements, so they will detect both
series and parallel arcs (if the AFCIs ever appear).
Detecting a 5A 'bad' arc while ignoring an acceptable arc, like a brush
motor, does not sound easy.
The ground fault detection level required in AFCIs is 5A. The article
says AFCIs on the market detect at 50mA. The ones I have seen are at
30mA. I believe the theory is that an arc with a ground present is
likely to soon arc to ground and be detected.
Among the information in the article is where the 5 and 75A levels came
from.
--
bud--
| |
| Beachcomber 2007-04-20, 5:25 pm |
|
>Detecting a 5A 'bad' arc while ignoring an acceptable arc, like a brush
>motor, does not sound easy.
>
>The ground fault detection level required in AFCIs is 5A. The article
>says AFCIs on the market detect at 50mA. The ones I have seen are at
>30mA. I believe the theory is that an arc with a ground present is
>likely to soon arc to ground and be detected.
>
>
>Among the information in the article is where the 5 and 75A levels came
>from.
>
>--
I think the whole idea of AFCI's and their adoption by the US
Electrical Code and Consumer Safety Organizations was because, there
were, at most, one or two deaths per year caused by fires started in
bedrooms caused by bedframes smashing into plugs/outlets. Americans
in general, and the keepers of the NEC specifically like to error on
the side of caution, especially if the economic cost is not too high.
Also, just the fact that a plug/outlet was located behind the bed
would increase the risk of fire.
That being said, most of the electrical devices used in bedrooms are
going to be two wire devices, (lamps, electric space heaters, clocks,
vacuum cleaners, radios, cell phone/cordless phone chargers, etc.)
Three wire arc-fault detection would be normally not add any greater
protection for most applianced used in this location.
Thus, any fault to ground, even an arc-fault could conceivably be
protected by conventional, less-expensive GFCI's (although not
currenlty required in bedrooms).
| |
| phil-news-nospam@ipal.net 2007-04-21, 8:25 pm |
| On Thu, 19 Apr 2007 21:31:35 -0400 gfretwell@aol.com wrote:
| On 20 Apr 2007 01:04:47 GMT, phil-news-nospam@ipal.net wrote:
|
|>| Most AFCI trips get traced back to ground/neutral faults. That is
|>| where the ceiling fans got that bad reputation. It was usually that
|>| big cludge wirenut vibrating into the hickey when the fan was running.
|>| The original AFCI designs (for the arc fault part) were only looking
|>| for short duration current spikes in the 70a+ range. They just detect
|>| dead shorts from line to neutral. The GFCI protection was added to
|>| find shorts from neutral or line to ground at the 30ma level.
|>
|>That's not what some aspects of what I read say. There have been documents
|>(I didn't keep them handy) that described "series arcs" as arcs due to a
|>loose connection that isn't a short circuit path. The arc transients would
|>therefore have no more increase than what the load is, plus or minus any
|>circuit/load reactive components affecting it.
|>
|>--
|
| There are not any "series arc" detectors out there yet., Siemens is
| bragging about having one but it isn't really for sale.
| The "combination" AFCI refers to being able to detect parallel arcs in
| the wall plus an arc in a line cord. It is a lower level of current
| detection when looking at a potential arc.
What is the difference between those kinds of arcs that would require a
combination device to detect either?
So if I take a power cord with a plug on one end, and open stranded wire
on the other end, plug the plug into a 120V output, and take the open ends
(held by the insulation), and just quickly slap them across each other and
back apart again (with eyes turned away), if a magnetic trip doesn't open
on that (and I suspect it won't ... don't try this at home), would an AFCI
catch it and open when a magnetic trip won't?
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-04-21-1935@ipal.net |
|------------------------------------/-------------------------------------|
| |
| phil-news-nospam@ipal.net 2007-04-21, 8:25 pm |
| On Fri, 20 Apr 2007 11:53:33 -0500 Bud-- <remove.BudNews@isp.com> wrote:
| The currently required "Branch/feeder" AFCIs are required to detect 75A
| arcs. That will detect parallel arcs, but not series arcs.
What about a 3/4 HP garbage disposal motor starting up against a drain
jammed tight with the dinner waste?
| "Outlet circuit" AFCIs are required to detect 5A arcs, which will detect
| series and parallel arcs.
|
| The "Combination" AFCIs required by the NEC on 1-1-08 combine "Outlet
| circuit" and "Branch/feeder" requirements, so they will detect both
| series and parallel arcs (if the AFCIs ever appear).
So the NEC require in less than a year (where AHJs adopt it all) a product
that still hasn't shown up on the market?
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-04-21-1939@ipal.net |
|------------------------------------/-------------------------------------|
| |
| phil-news-nospam@ipal.net 2007-04-21, 8:25 pm |
| On Fri, 20 Apr 2007 21:50:50 GMT Beachcomber <invalid@notreal.none> wrote:
| I think the whole idea of AFCI's and their adoption by the US
| Electrical Code and Consumer Safety Organizations was because, there
| were, at most, one or two deaths per year caused by fires started in
| bedrooms caused by bedframes smashing into plugs/outlets. Americans
| in general, and the keepers of the NEC specifically like to error on
| the side of caution, especially if the economic cost is not too high.
| Also, just the fact that a plug/outlet was located behind the bed
| would increase the risk of fire.
It would also help to require sufficient extra outlets in bedrooms so that
the ones that do get covered up by furniture won't matter because at least
one other nearby will be available. How about a duplex every 2 feet?
In my current home (I didn't design), I have 3 outlets, 2 of which are in
bedrooms, with "permanent" extension cords because they are located where
the only option for furniture exists, and another outlet is too far away.
The builder clearly put the absolute minimum in to meet code. It would
now be very expensive to stick in new ones to meet my suggested spacing.
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-04-21-1944@ipal.net |
|------------------------------------/-------------------------------------|
| |
| gfretwell@aol.com 2007-04-22, 3:25 am |
| On 22 Apr 2007 00:48:47 GMT, phil-news-nospam@ipal.net wrote:
>It would also help to require sufficient extra outlets in bedrooms so that
>the ones that do get covered up by furniture won't matter because at least
>one other nearby will be available. How about a duplex every 2 feet?
This is a design issue. If the designer can identify the likely bed
locations they can place the outlets properly for the night stands. In
my bedroom remodel this ended up being 4 quads and two 4 way switch
loops with switches at 3 locations for the overhead and one switched
receptacle in each quad. Most builders hitting a price point will not
do this.
In the quads that ended up being away from the bed location I swapped
a duples for one of those green nightlights.
| |
| gfretwell@aol.com 2007-04-22, 3:25 am |
| On 22 Apr 2007 00:39:26 GMT, phil-news-nospam@ipal.net wrote:
>| There are not any "series arc" detectors out there yet., Siemens is
>| bragging about having one but it isn't really for sale.
>| The "combination" AFCI refers to being able to detect parallel arcs in
>| the wall plus an arc in a line cord. It is a lower level of current
>| detection when looking at a potential arc.
>
>What is the difference between those kinds of arcs that would require a
>combination device to detect either?
>
>So if I take a power cord with a plug on one end, and open stranded wire
>on the other end, plug the plug into a 120V output, and take the open ends
>(held by the insulation), and just quickly slap them across each other and
>back apart again (with eyes turned away), if a magnetic trip doesn't open
>on that (and I suspect it won't ... don't try this at home), would an AFCI
The difference is available fault current. You may never generate the
75a on the end of an 18ga lamp cord, particularly if it was connected
in a flaky 43 cent receptacle with loose contacts.
| |
|
| phil-news-nospam@ipal.net wrote:
> On Fri, 20 Apr 2007 11:53:33 -0500 Bud-- <remove.BudNews@isp.com> wrote:
>
> | The currently required "Branch/feeder" AFCIs are required to detect 75A
> | arcs. That will detect parallel arcs, but not series arcs.
>
> What about a 3/4 HP garbage disposal motor starting up against a drain
> jammed tight with the dinner waste?
>
It is a simple overload, not an arc. The arc fault mechanism wouldn't
detect it. But the normal overload mechanism of a branch/feeder circuit
breaker would.
>
> | "Outlet circuit" AFCIs are required to detect 5A arcs, which will detect
> | series and parallel arcs.
> |
> | The "Combination" AFCIs required by the NEC on 1-1-08 combine "Outlet
> | circuit" and "Branch/feeder" requirements, so they will detect both
> | series and parallel arcs (if the AFCIs ever appear).
>
> So the NEC require in less than a year (where AHJs adopt it all) a product
> that still hasn't shown up on the market?
>
Yup.
The 1-1-08 requirement is in the 2002 NEC (like post dating a check). It
may have been reasonable to expect the new AFCIs would be on the market
when they wrote the 2002 code.
What IMHO was a irresponsible move was requiring in the 2008 NEC
(assuming it hasn't been removed late in the code process) that almost
all 15 & 20A 120V residential circuits be protected by AFCIs. These will
have to be the new AFCIs that were not on the market when they wrote the
2008 code. It was likely the new devices would have little field
experience before they were required 'everywhere'.
It will be interesting what changes jurisdictions make when they accept
the 2008 NEC. If, for example, SquareD does not have the new AFCIs
available does that mean you can't use SquareD panels.
--
bud--
| |
| gfretwell@aol.com 2007-04-23, 1:25 pm |
| On Mon, 23 Apr 2007 10:18:49 -0500, Bud-- <remove.BudNews@isp.com>
wrote:
>The 1-1-08 requirement is in the 2002 NEC (like post dating a check). It
>may have been reasonable to expect the new AFCIs would be on the market
>when they wrote the 2002 code.
They actually put AFCIs in the 99 code to be implimented in 2002 and
that device did not really exist in retail channels in 1997 when the
ROP came out.
| |
|
| Beachcomber wrote:
>
> I think the whole idea of AFCI's and their adoption by the US
> Electrical Code and Consumer Safety Organizations was because, there
> were, at most, one or two deaths per year caused by fires started in
> bedrooms caused by bedframes smashing into plugs/outlets. Americans
> in general, and the keepers of the NEC specifically like to error on
> the side of caution, especially if the economic cost is not too high.
> Also, just the fact that a plug/outlet was located behind the bed
> would increase the risk of fire.
I have never seen bedframes hitting plugs as a cause behind AFCIs.
Electrical cords lying on the floor that get walked on, under rugs, or
otherwise abused have been mentioned. There was an economic analysis
done by the CPSC. It was based on the number of electrical fires with
bedrooms a major point of origin. According to the analysis, AFCIs were
cost-effective in preventing fire damage, injury and death. The analysis
may be right or wrong, but there was a justification for AFCIs in bedrooms.
But I don’t think there was any study that demonstrated the
effectiveness of AFCIs that have been installed in bedrooms that was
used as a basis for extending the use of AFCIs ‘everywhere’.
>
> That being said, most of the electrical devices used in bedrooms are
> going to be two wire devices, (lamps, electric space heaters, clocks,
> vacuum cleaners, radios, cell phone/cordless phone chargers, etc.)
Two wire cord s produce parallel faults, which is what the existing
AFCIs are required to detect. One of the UL AFCI tests is for parallel
arcs in “zip” cord, which is the common electrical cord in bedrooms. The
75A parallel arc detection level is based on UL field tests of outlets
that found 75A was available for a fault at all tested outlets and at
the end of almost all plugged in lengths of 6 feet of #18.
>
> Three wire arc-fault detection would be normally not add any greater
> protection for most applianced used in this location.
One of the UL AFCI tests is for a series arc in Romex with ground. Since
existing AFCIs don’t detect series arcs I presume detection is by the
series arc becoming at least partially a ground fault which will be
detected.
Also UL did some tests on “glowing connections” - series arcs - at wire
connections to receptacles. In 9 of 16 tests leakage to ground developed
that tripped an AFCI. (In 6 of 16 tests the wire burned open.)
>
> Thus, any fault to ground, even an arc-fault could conceivably be
> protected by conventional, less-expensive GFCI's (although not
> currenlty required in bedrooms).
But that wouldn’t detect parallel arcs that don’t involve ground. Or, if
the new AFCIs ever appear, series arcs that don’t involve ground. And an
arc fault with a ground present does not necessarily develop ground leakage.
--
bud--
| |
| gfretwell@aol.com 2007-04-23, 9:25 pm |
| On Mon, 23 Apr 2007 19:11:41 -0500, Bud-- <remove.BudNews@isp.com>
wrote:
>There was an economic analysis
>done by the CPSC. It was based on the number of electrical fires with
>bedrooms a major point of origin. According to the analysis, AFCIs were
>cost-effective in preventing fire damage, injury and death.
The study I saw at Electrical Contractor Network forum pegged the
price at several million dollars per fire prevented and a couple
billion dollars per life saved. (using NFPA fire data and industry
projections of AFCIs to be sold at $40 each.)
| |
| phil-news-nospam@ipal.net 2007-04-25, 5:25 pm |
| On Sun, 22 Apr 2007 00:35:03 -0400 gfretwell@aol.com wrote:
| On 22 Apr 2007 00:48:47 GMT, phil-news-nospam@ipal.net wrote:
|
|>It would also help to require sufficient extra outlets in bedrooms so that
|>the ones that do get covered up by furniture won't matter because at least
|>one other nearby will be available. How about a duplex every 2 feet?
|
|
| This is a design issue. If the designer can identify the likely bed
| locations they can place the outlets properly for the night stands. In
| my bedroom remodel this ended up being 4 quads and two 4 way switch
| loops with switches at 3 locations for the overhead and one switched
| receptacle in each quad. Most builders hitting a price point will not
| do this.
| In the quads that ended up being away from the bed location I swapped
| a duples for one of those green nightlights.
I also think it is a code issue. The code writers _are_ legitimately
concerned with safety, including those aspects that result in fires due
to damage in cords plugged into outlets. That's one justification for
AFCI requirements. Closer outlet spacing, especially in bedrooms, would
also further the cause of greater safety.
Of course it is my intent to design a house with much better electrical
wiring along the lines of my own desires. This will include more outlets
than the code requires, including the previously mentioned extras in the
bedrooms and other rooms where furniture may concentrate (all outlets may
still be covered, but at least some will end up being behind light weight
furniture, instead of behind a bookcase full of books). I don't know
that I need quads in the bedrooms, given the extra outlets. But a few
other places definitely will have them.
My kitchen pattern will be a little more complex. Each point will have
2x duplex 5-15R, 1x single 5-20R, 1x single 6-20R. The singles will be
each on their own dedicated circuit. The duplexes will be on 2 circuits
but will share the circuit with the outlet point 2 or 3 points down for
a total of 4 or 6 circuits. My father knows an electritician who went
to the extreme of every duplex on its own dedicated shared neutral in the
kitchen. But I figure if I need more than the 4 to 6 multi-outlet circuits
plus all the single-outlet dedicated circuits, I have other issues to worry
about (like how to dump all the heat).
I'd like to do this in the kitchen:
http://phil.ipal.org/usenet/aee/ks-1.html
but it would more likely have to be:
http://phil.ipal.org/usenet/aee/ks-2.html
although these might be done with a 3 pole breaker for the right duplex:
http://phil.ipal.org/usenet/aee/ks-3.html
http://phil.ipal.org/usenet/aee/ks-4.html
And no 3-way/4-way switches for me. Momentary up/down switches controlling
relays (machnically latching in some cases, electrically held on in others)
is my current plan at least for multi-point controlled lights and maybe a
few others.
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-04-25-1638@ipal.net |
|------------------------------------/-------------------------------------|
| |
| phil-news-nospam@ipal.net 2007-04-25, 5:25 pm |
| On Mon, 23 Apr 2007 19:11:41 -0500 Bud-- <remove.BudNews@isp.com> wrote:
| I have never seen bedframes hitting plugs as a cause behind AFCIs.
| Electrical cords lying on the floor that get walked on, under rugs, or
| otherwise abused have been mentioned. There was an economic analysis
Including chewed on by animals.
| done by the CPSC. It was based on the number of electrical fires with
| bedrooms a major point of origin. According to the analysis, AFCIs were
| cost-effective in preventing fire damage, injury and death. The analysis
| may be right or wrong, but there was a justification for AFCIs in bedrooms.
|
| But I don?t think there was any study that demonstrated the
| effectiveness of AFCIs that have been installed in bedrooms that was
| used as a basis for extending the use of AFCIs ?everywhere?.
Animals can get out of the bedroom.
|> That being said, most of the electrical devices used in bedrooms are
|> going to be two wire devices, (lamps, electric space heaters, clocks,
|> vacuum cleaners, radios, cell phone/cordless phone chargers, etc.)
|
| Two wire cord s produce parallel faults, which is what the existing
| AFCIs are required to detect. One of the UL AFCI tests is for parallel
| arcs in ?zip? cord, which is the common electrical cord in bedrooms. The
| 75A parallel arc detection level is based on UL field tests of outlets
| that found 75A was available for a fault at all tested outlets and at
| the end of almost all plugged in lengths of 6 feet of #18.
|
|>
|> Three wire arc-fault detection would be normally not add any greater
|> protection for most applianced used in this location.
|
| One of the UL AFCI tests is for a series arc in Romex with ground. Since
| existing AFCIs don?t detect series arcs I presume detection is by the
| series arc becoming at least partially a ground fault which will be
| detected.
|
| Also UL did some tests on ?glowing connections? - series arcs - at wire
| connections to receptacles. In 9 of 16 tests leakage to ground developed
| that tripped an AFCI. (In 6 of 16 tests the wire burned open.)
Loose plugs can also cause this.
Back in 1979 there was a fire that destroyed an entire apartment building
in a large apartment complex I lived in. The fire was ultimately traced
down to the receptacles being painted, and subsequent poor contact when a
plug is pushed in. That's not exactly an AFCI issue, but in certain cases
I could see where a series arc detection might catch this.
|> Thus, any fault to ground, even an arc-fault could conceivably be
|> protected by conventional, less-expensive GFCI's (although not
|> currenlty required in bedrooms).
|
| But that wouldn?t detect parallel arcs that don?t involve ground. Or, if
| the new AFCIs ever appear, series arcs that don?t involve ground. And an
| arc fault with a ground present does not necessarily develop ground leakage.
|
| --
| bud--
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-04-25-1701@ipal.net |
|------------------------------------/-------------------------------------|
| |
| phil-news-nospam@ipal.net 2007-04-25, 5:25 pm |
| On Mon, 23 Apr 2007 10:18:49 -0500 Bud-- <remove.BudNews@isp.com> wrote:
| It will be interesting what changes jurisdictions make when they accept
| the 2008 NEC. If, for example, SquareD does not have the new AFCIs
| available does that mean you can't use SquareD panels.
I'm already planning to go with C-H panels.
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-04-25-1708@ipal.net |
|------------------------------------/-------------------------------------|
|
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