|
Home > Archive > Electrical Engineering > June 2005 > Drilled a power cable
You are viewing an archived Text-only version of the thread.
To view this thread in it's original format and/or if you want to reply to
this thread please [click here]
| Author |
Drilled a power cable
|
|
| Simon 2005-06-23, 12:25 pm |
| Whilst putting up a picture I drilled into the wall and hit a sunken 240v
power cable going to a 13amp plug socket. It threw the house trip but when
I reset it all seems to work okay & the socket works fine (although I
haven't the equipment to test it, just plugged a lamp in)
What is the best course of action;
+ Fill the hole and leave alone (but if I have weakened the cable could this
cause a fire?)
+ Dig out the wall and make a join in the cable (It is right by the front
door so anything but a very good filling job will show & what should I use
to make the join?)
+ Lift the carpet and floorboards above and pull a new cable through, making
a join in the ceiling void.
+ None of the above or Move house (only joking!)
Many thanks
| |
| TimPerry 2005-06-23, 12:25 pm |
|
"Simon" <someone@nospam.com> wrote in message
news:Qnyue.950$rz1.793@newsfe5-gui.ntli.net...
quote:
> Whilst putting up a picture I drilled into the wall and hit a sunken 240v
> power cable going to a 13amp plug socket. It threw the house trip but
when
quote:
> I reset it all seems to work okay & the socket works fine (although I
> haven't the equipment to test it, just plugged a lamp in)
>
> What is the best course of action;
> + Fill the hole and leave alone (but if I have weakened the cable could
this
quote:
> cause a fire?)
how well will you sleep if you do this?
quote:
> + Dig out the wall and make a join in the cable (It is right by the front
> door so anything but a very good filling job will show & what should I use
> to make the join?)
you are going to hang a picture over it anyway
quote:
> + Lift the carpet and floorboards above and pull a new cable through,
making
quote:
> a join in the ceiling void.
may be difficult as the wires are usully stapled to studs when installed
quote:
> + None of the above or Move house (only joking!)
turn off electricity and revert to coal? (joke too!)
quote:
>
> Many thanks
>
>
| |
| Ben Miller 2005-06-23, 11:25 pm |
| Options 2 or 3 only. Option 1 is NOT a good choice!
Ben Miller
--
Benjamin D. Miller, PE
B. MILLER ENGINEERING
www.bmillerengineering.com
"Simon" <someone@nospam.com> wrote in message
news:Qnyue.950$rz1.793@newsfe5-gui.ntli.net...
quote:
> Whilst putting up a picture I drilled into the wall and hit a sunken 240v
> power cable going to a 13amp plug socket. It threw the house trip but
> when I reset it all seems to work okay & the socket works fine (although I
> haven't the equipment to test it, just plugged a lamp in)
>
> What is the best course of action;
> + Fill the hole and leave alone (but if I have weakened the cable could
> this cause a fire?)
> + Dig out the wall and make a join in the cable (It is right by the front
> door so anything but a very good filling job will show & what should I use
> to make the join?)
> + Lift the carpet and floorboards above and pull a new cable through,
> making a join in the ceiling void.
> + None of the above or Move house (only joking!)
>
> Many thanks
>
>
| |
| Palindr☻me 2005-06-23, 11:25 pm |
| Simon wrote:
quote:
> Whilst putting up a picture I drilled into the wall and hit a sunken 240v
> power cable going to a 13amp plug socket. It threw the house trip but when
> I reset it all seems to work okay & the socket works fine (although I
> haven't the equipment to test it, just plugged a lamp in)
>
> What is the best course of action;
> + Fill the hole and leave alone (but if I have weakened the cable could this
> cause a fire?)
> + Dig out the wall and make a join in the cable (It is right by the front
> door so anything but a very good filling job will show & what should I use
> to make the join?)
> + Lift the carpet and floorboards above and pull a new cable through, making
> a join in the ceiling void.
> + None of the above or Move house (only joking!)
>
> Many thanks
>
>
You need to locate where the cable goes from and to - which
will also allow you to identify whether it is part of the
ring or just a spur off it.
If it is part of the ring, then you may have parted a
conductor without any apparent effect on any of the sockets.
With the ring being incomplete the fuse/breaker is not going
to give adequate protection to the remaining cables - which
will greatly increase the risk of a fire at worst and hasten
the day of a complete rewire of the ring, at the very least.
The most suitable repair is to replace the cable - typically
it will just be a short run from one socket to the next on
the ring. Typically, you don't have to run the replacement
cable through the same route - as long as it runs between
the same two points.
It may be possible to pull a new cable through, using the
old cable - depending on how it was installed - eg in a tray
under the plaster.
It may also be possible, depending on how the ring is
configured and where the cables run, to convert the socket
to which it runs to a spur, using the remaining undamaged
cable, and remake the ring. Disconnecting and isolating the
damaged cable, of course.
So, firstly look to see if you can replace the entire
damaged cable, back to the points at which it connects to
the ring.
If that isn't possible, consider whether you need the socket
to which the cable goes. You may be able to remake the ring,
bypassing the socket completely - then remove it and
plaster up the hole.
If that isn't possible, look to see if the ring could be
remade, with the damaged cable disconnected and the good
cable used as a spur to that particular socket.You won't be
able to do this if you have already reached the spur limit
on the ring.
If that isn't possible and it is a ring cable and not a
spur, look to fitting say a fused spur outlet in the spot
where the hole is. You may be able to pull through enough
slack to do this - the cable is probably run in a plastic
tray under the plaster. Depending on the location, the fused
spare could actually look intentional and could even be
useful...
The choices go on and on - depending on the actual layout
you have and what your priorities are.
What you don't want is an inaccessible screw-down join -
especially buried in the wall or even under the floorboards.
--
Sue
| |
| phil-news-nospam@ipal.net 2005-06-24, 6:25 pm |
| On Fri, 24 Jun 2005 00:30:50 +0100 Palindr?me <sb382638@hotmail.com.invalid> wrote:
| If it is part of the ring, then you may have parted a
| conductor without any apparent effect on any of the sockets.
| With the ring being incomplete the fuse/breaker is not going
| to give adequate protection to the remaining cables - which
| will greatly increase the risk of a fire at worst and hasten
| the day of a complete rewire of the ring, at the very least.
This is one of the reasons I believe ring circuits to be fundamentally
unsafe. It is because a wire can become disconnected in some way but
the circuit will not give any appearance of a problem while the wires
remaining will overheat at full capacity.
--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------
| |
|
| Palindr☻me wrote:
quote:
> Simon wrote:
>
> You need to locate where the cable goes from and to - which will also
> allow you to identify whether it is part of the ring or just a spur off it.
>
I am assuming a ring is a circuit that starts in a panel and goes
sequentially to the outlets and returns to the panel where both ends of
the ring are connected. I have never seen this configuration and doubt
it would be used because of added cost and minimal advantage.
quote:
> If it is part of the ring, then you may have parted a conductor without
> any apparent effect on any of the sockets. With the ring being
> incomplete the fuse/breaker is not going to give adequate protection to
> the remaining cables - which will greatly increase the risk of a fire at
> worst and hasten the day of a complete rewire of the ring, at the very
> least.
>
If a ring is as described, breaking it would have no effect on
protection - the whole cable would have to be rated for the branch
circuit rating. The damaged segment could be disconnected at its ends.
Is ring something else?
Bud--
| |
| Michael A. Terrell 2005-06-24, 11:25 pm |
| Bud wrote:
quote:
>
> Palindr☻me wrote:
>
> I am assuming a ring is a circuit that starts in a panel and goes
> sequentially to the outlets and returns to the panel where both ends of
> the ring are connected. I have never seen this configuration and doubt
> it would be used because of added cost and minimal advantage.
>
>
> If a ring is as described, breaking it would have no effect on
> protection - the whole cable would have to be rated for the branch
> circuit rating. The damaged segment could be disconnected at its ends.
>
> Is ring something else?
>
> Bud--
No, you've figured out the basics. Its used in the UK, but its
illegal in the US.
--
Former professional electron wrangler.
Michael A. Terrell
Central Florida
| |
| Palindr☻me 2005-06-24, 11:25 pm |
| Bud wrote:
quote:
> Palindr=E2=98=BBme wrote:
>=20
[vbcol=seagreen]
[vbcol=seagreen]
>=20
> I am assuming a ring is a circuit that starts in a panel and goes=20
> sequentially to the outlets and returns to the panel where both ends of=
=20
quote:
> the ring are connected. I have never seen this configuration and doubt=
=20
quote:
> it would be used because of added cost and minimal advantage.
The OP is posting from BST - i.e the UK. Using a ring=20
circuit is standard practice in the UK. The mention of 13A=20
was also a give-away.
quote:
>=20
=20[vbcol=seagreen]
[vbcol=seagreen]
>=20
> If a ring is as described, breaking it would have no effect on=20
> protection - the whole cable would have to be rated for the branch=20
> circuit rating. The damaged segment could be disconnected at its ends.
>=20
> Is ring something else?
>=20
I am sorry but I suggest that you research UK wiring=20
practice before giving advice relating to it. A UK ring is=20
actually fused at a higher rating than an individual cable=20
capacity, believe it or not, it just happens to be true.
You can then work out for yourself the effect of leaving out=20
a segment - the cables in the multi-drop "spurs" created=20
would not be adequately protected unless the fuse was=20
changed also.
Wiring practice does vary a lot around the World but I must=20
admit that using the time zone to identify the location can=20
be misleading - AFAIK, Haiti shares a time zone with the=20
USA, but the wiring practice is a tad different...
--=20
Sue
| |
| Simon 2005-06-24, 11:25 pm |
| Hey all - thanks for the advice - yes I am in the uk.
I'm thinking a lower fuse for now should offer some protection until I
figure the long term answer.
"Palindr?me" <sb382638@hotmail.com.invalid> wrote in message
news:11bouqo9j74th8c@corp.supernews.com...
Bud wrote:
quote:
> Palindr?me wrote:
>
>
> I am assuming a ring is a circuit that starts in a panel and goes
> sequentially to the outlets and returns to the panel where both ends of
> the ring are connected. I have never seen this configuration and doubt it
> would be used because of added cost and minimal advantage.
The OP is posting from BST - i.e the UK. Using a ring
circuit is standard practice in the UK. The mention of 13A
was also a give-away.
quote:
>
>
> If a ring is as described, breaking it would have no effect on
> protection - the whole cable would have to be rated for the branch circuit
> rating. The damaged segment could be disconnected at its ends.
>
> Is ring something else?
>
I am sorry but I suggest that you research UK wiring
practice before giving advice relating to it. A UK ring is
actually fused at a higher rating than an individual cable
capacity, believe it or not, it just happens to be true.
You can then work out for yourself the effect of leaving out
a segment - the cables in the multi-drop "spurs" created
would not be adequately protected unless the fuse was
changed also.
Wiring practice does vary a lot around the World but I must
admit that using the time zone to identify the location can
be misleading - AFAIK, Haiti shares a time zone with the
USA, but the wiring practice is a tad different...
--
Sue
| |
| Andrew Gabriel 2005-06-24, 11:25 pm |
| In article <d9h728416uc@news1.newsguy.com>,
phil-news-nospam@ipal.net writes:
quote:
>
>This is one of the reasons I believe ring circuits to be fundamentally
>unsafe. It is because a wire can become disconnected in some way but
>the circuit will not give any appearance of a problem while the wires
>remaining will overheat at full capacity.
This is a theoretical possibility, but in practice it seems
not to happen, or at least, not to be a source of fires.
This may be because it is in practice extremely rare that a
ring is run anywhere near full load (7.5kW).
OTOH, if you do get a bad connection in a ring which starts
going high resistance, it doesn't overheat because there's
an alternative path.
--
Andrew Gabriel
| |
| Michael Moroney 2005-06-24, 11:25 pm |
| "Michael A. Terrell" <mike.terrell@earthlink.net> writes:
quote:
[vbcol=seagreen]
> No, you've figured out the basics. Its used in the UK, but its
>illegal in the US.
What is the purpose of wiring a ring circuit? I suppose in theory it
could carry twice the current safely (a ring wired with 14 gauge could
carry 30A), but an undetected break or a problem like what the original
poster had gives me the heebie-jeebies. If they use a size close to 14
gauge with the 13A breaker mentioned, I see no real advantage.
| |
| VWWall 2005-06-25, 4:25 am |
| Michael Moroney wrote:
quote:
> "Michael A. Terrell" <mike.terrell@earthlink.net> writes:
>
>
>
>
>
>
>
> What is the purpose of wiring a ring circuit? I suppose in theory it
> could carry twice the current safely (a ring wired with 14 gauge could
> carry 30A), but an undetected break or a problem like what the original
> poster had gives me the heebie-jeebies. If they use a size close to 14
> gauge with the 13A breaker mentioned, I see no real advantage.
It also has half the voltage drop to a given outlet. I once did some
comparison on using ring circuits in typical USA situations. It looses
much of its value when lighting is at 120V and large appliances are at
240V. Also the typical urban "flat" in the UK can use a ring circuit(s)
in a way that the typical USA dwelling cannot. It does save on copper!
--
Virg Wall, P.E.
| |
| Michael A. Terrell 2005-06-25, 4:25 am |
| VWWall wrote:
quote:
>
> It also has half the voltage drop to a given outlet. I once did some
> comparison on using ring circuits in typical USA situations. It looses
> much of its value when lighting is at 120V and large appliances are at
> 240V. Also the typical urban "flat" in the UK can use a ring circuit(s)
> in a way that the typical USA dwelling cannot. It does save on copper!
>
> --
> Virg Wall, P.E.
I don't worry about how much copper I use for my own use, and most of
my commercial work was in communications, so you had to use the
specified cabling for the contract.
People tell me that I'm weird because I use EMT for all the wiring on
my property, but it is my property, and I would rather spend a little
more and not have to worry about damage, or what could happen to one or
more of the buildings if the wiring is damaged.
--
Former professional electron wrangler.
Michael A. Terrell
Central Florida
| |
| Michael A. Terrell 2005-06-25, 4:25 am |
| Michael Moroney wrote:
quote:
>
> "Michael A. Terrell" <mike.terrell@earthlink.net> writes:
>
>
>
> What is the purpose of wiring a ring circuit? I suppose in theory it
> could carry twice the current safely (a ring wired with 14 gauge could
> carry 30A), but an undetected break or a problem like what the original
> poster had gives me the heebie-jeebies. If they use a size close to 14
> gauge with the 13A breaker mentioned, I see no real advantage.
I think that is the reason they are not allowed in the US. They want
it to be obvious that there is a fault, before there is major damage or
even a death.
--
Former professional electron wrangler.
Michael A. Terrell
Central Florida
| |
| VWWall 2005-06-25, 4:25 am |
| Michael A. Terrell wrote:
quote:
> I don't worry about how much copper I use for my own use, and most of
> my commercial work was in communications, so you had to use the
> specified cabling for the contract.
I agree! One of the worst things that happened to commercial
communications equipment was the use of cheap "RCA" jacks and RF
connectors that use the co-ax conductor as the center connector.
In the early 50's, I knew contractors that used only #12 wire. The
extra cost was made up by not stocking both #12 and #14. With the cost
of copper now that's not possible.
quote:
> People tell me that I'm weird because I use EMT for all the wiring on
> my property, but it is my property, and I would rather spend a little
> more and not have to worry about damage, or what could happen to one or
> more of the buildings if the wiring is damaged.
I built a house in Santa Barbara, CA, and wired it myself using EMT. It
really isn't that much more difficult or expensive than flex. I also
did the plumbing using cast iron sewer pipe. (I'd be tempted to use
plastic now!):-)
--
Virg Wall, P.E., K6EVE
| |
| Michael A. Terrell 2005-06-25, 12:25 pm |
| VWWall wrote:
quote:
>
> Michael A. Terrell wrote:
>
> I agree! One of the worst things that happened to commercial
> communications equipment was the use of cheap "RCA" jacks and RF
> connectors that use the co-ax conductor as the center connector.
I've used thousands of PL259 and BNC connectors at radio and TV stations
over the last 35 years. I've used a lot of "N", "HN" and "SMA"
connectors working in Telemetry, plus some "F" and hardline connectors
when I engineered CATV systems. Not many "RCA" (AKA Phono) connectors
outside of consumer electronics.
Some "F" fittings are actually fairly good, but they are rarely used
outside of a CATV headend. They have low RF leakage, and a very small
impedance bump when you look at the line with a TDR. The common
separate ring or chinese made gold plated stuff is real garbage. When I
worked for United Video I tested samples of all RF distribution items in
our lab before they were allowed to be used in the field. I failed most
connectors by simply tightening them to the rated spec and watching them
snap, or strip the threads. I had to laugh at one sample lot. SOme
company sent us a couple dozen "F-56" connectors machined out of good
brass. They were excellent quality, and met all the specs, except they
weren't plated. They wouldn't last a month in the winter time in
Cincinnati with all the road salt that gets stirred up and lands on the
overhead wires.
quote:
> In the early 50's, I knew contractors that used only #12 wire. The
> extra cost was made up by not stocking both #12 and #14. With the cost
> of copper now that's not possible.
>
>
> I built a house in Santa Barbara, CA, and wired it myself using EMT. It
> really isn't that much more difficult or expensive than flex. I also
> did the plumbing using cast iron sewer pipe. (I'd be tempted to use
> plastic now!):-)
>
> --
> Virg Wall, P.E., K6EVE
I still prefer to sweat copper for water supply and waste water
lines. You can take it apart and reuse it if needed, but plastic ends
up with extra splices with every repair.
The last work I did with black iron pipe was to install a new gas
service to my home in Ohio. The jerk from CG&E was gloating that no
home owner had ever passed the test on the first try, and he failed over
75% of the work contractors did, and that he got paid for every trip
back to the jobsite. He did a visual inspection of the new piping and
it was a "Kodak Moment"! His jaw dropped as he tried to figure out how
I got a 21 foot piece of pipe into a basement with no windows. I
finally felt sorry for him and explained that I dug the hole outside to
a deep slope and slid it in, then back filled the edge of the hole. Then
he got really mad when it passed on the first try. He tested it three
times, and grudgingly had to admit that "SOME" home owners knew what
they were doing.
--
Former professional electron wrangler.
Michael A. Terrell
Central Florida
| |
| stevenal 2005-06-27, 6:25 pm |
|
"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:42BC761C.7DD28C94@earthlink.net...
quote:
> Bud wrote:
lamp[vbcol=seagreen]
off it.[vbcol=seagreen]
without[vbcol=seagreen]
to[vbcol=seagreen]
at[vbcol=seagreen]
>
>
> No, you've figured out the basics. Its used in the UK, but its
> illegal in the US.
>
> --
> Former professional electron wrangler.
>
> Michael A. Terrell
> Central Florida
Where in the NEC is this adressed?
|
|
|
|
|