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#174553 - 02/07/08 09:28 PM How hot can conductors get before Its a problem?
frank Offline
Member

Registered: 05/29/01
Posts: 361
Loc: windsor ontario canada

Last night while adding circuits to a 200a panel i found that someone had fed a second panel by terminating the feeders on the main lugs of the first panel.The feeders to the second panel are smaller and warm to the touch.I didn't have time find the distrobution breaker to check It's size.I asked around and was told that just because the wires are warm dosen't mean it's a problem.I'll have to check it with the IR gun tommorow.thanks

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#174557 - 02/07/08 11:59 PM Re: How hot can conductors get before Its a proble [Re: frank]
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
 Originally Posted By: frank

Last night while adding circuits to a 200a panel i found that someone had fed a second panel by terminating the feeders on the main lugs of the first panel.The feeders to the second panel are smaller and warm to the touch.I didn't have time find the distrobution breaker to check It's size.I asked around and was told that just because the wires are warm dosen't mean it's a problem.I'll have to check it with the IR gun tommorow.thanks

You are telling us that you found conductor insulation hot enough to the touch and did not investigate further?
That to me alone, would ring alarm bells.
You'd better hope that them wires don't get any hotter, this is how building fires start.
It is not a IR gun you need, it is a clamp meter.
Having said that I would have cut the supply to that place before things got much worse.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

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#174566 - 02/08/08 07:08 AM Re: How hot can conductors get before Its a proble [Re: Trumpy]
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
Mike has a good point ... the temp you feel at one point may be quite a bit different at another point in the run.

The source of the problem could very well be that improper connection at the start of the circuit.

IR guns have their uses ... but they are no substitute to proper installation. Shoving two wires into a single lug is a pretty basic error.

Otherwise ... to answer your question ... you start running into trouble at 75C ... even if the wires have a higher rating on their particular insulation. Why? Because the places where the wires terminate are often only rated at 75C.

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#174570 - 02/08/08 08:06 AM Re: How hot can conductors get before Its a proble [Re: renosteinke]
JValdes Offline
Member

Registered: 06/03/07
Posts: 308
Loc: South Carolina
Move the sub panel feeders to a breaker that is the right size for the wire and the main in the sub. It's possible the doubling up on the wires under the lugs have come loose. There should not be more than one conductor in each lug unless the lug is rated for two conductors. You have no overcurrent protection on the feeder. And if you don't have a main in the sub you could be in real trouble. That means no protection at all. Hot wires are the result of two things, overcurrent or loose connections. This should be addressed today.

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#174574 - 02/08/08 08:59 AM Re: How hot can conductors get before Its a proble [Re: JValdes]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
You have bigger problems than simply the listing of the lug and possibly undersized feeder conductors. If these are really stabbed into the line side of the service disconnect these are SERVICE conductors. That opens a whole big can of worms.
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#174588 - 02/08/08 12:59 PM Re: How hot can conductors get before Its a problem? [Re: frank]
macmikeman Offline
Member

Registered: 07/16/02
Posts: 718
Loc: Honolulu, Hawaii
 Originally Posted By: frank

Last night while adding circuits to a 200a panel i found that someone had fed a second panel by terminating the feeders on the main lugs of the first panel.The feeders to the second panel are smaller and warm to the touch.I didn't have time find the distrobution breaker to check It's size.I asked around and was told that just because the wires are warm dosen't mean it's a problem.I'll have to check it with the IR gun tommorow.thanks


I second all the above comments, and would like to take the time to add:
Hello Frank, I have something in common with you, I was born in your little burg across the river from motor city in the Hotel Deux. Went to elementary school at St. Thomas in Riverside. The internet makes for a small planet.

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#174662 - 02/10/08 06:15 PM Re: How hot can conductors get before Its a problem? [Re: macmikeman]
frank Offline
Member

Registered: 05/29/01
Posts: 361
Loc: windsor ontario canada
I should have explained the situation better This is a hospital that it currently under construction.The work has not been released to us yet so I can't touch it.The EE and project coordinator were both notified as soon as it was found and this is where my involvment ends.The conductors were so tight i couldn't get the clampon near them without a pry bar.The reason i asked was that someone said the conductors were designed for the load and can operate worm.Ive never heard of such an animal except for mineral insulated firewire.And this isn't MI
thanks

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#174663 - 02/10/08 06:33 PM Re: How hot can conductors get before Its a problem? [Re: frank]
frank Offline
Member

Registered: 05/29/01
Posts: 361
Loc: windsor ontario canada
Macmikeman It's -10F here with a foot of snow and Windsor/Detroit is in bad shape because of the auto sector.Most of the machine tool is gone and Im hearing the big have dropped the starting wage from 36 to 19 an hour for skilled trades.Windsor lost 8000 jobs in 07 from plant closure and FORD just closed the Nemac engine plant on friday.Glad to hear you made it out alive.
good luck

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#174672 - 02/11/08 08:32 AM Re: How hot can conductors get before Its a problem? [Re: frank]
SteveFehr Offline
Member

Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
"Warm" is one thing. All wires generate heat, and it's perfectly normal- after all, they're designed to work up to 75-90C in the worst-case scenario. If all the other wires in the box have no-load, it may only seem bad by comparison. "Hot" under normal operating conditions is quite altogether something different. Abnormal heat in this wire could indicate a problem- poor connection or undersized wire, for instance. If you think it's an issue, I'd get the prybar the clamp a meter on there ASAP to verify it's simply due to loading on the circuit. Can you access the far end of the circuit?

If this is a branch circuit supplying a fixed design load close to the NEC ampacity of the wire and temps are only slightly elevated above ambient, I wouldn't worry about it. But if by "warm" you mean "I burned my hand", then you may have a problem.

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