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#104641 - 09/17/03 07:34 PM The death of a very loose grounded conductor!  
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
[Linked Image]
The death of a very loose grounded conductor!

[This message has been edited by Joe Tedesco (edited 03-12-2005).]


Joe Tedesco, NEC Consultant

2017 / 2014 NEC & Related Books and Study Guides

#104642 - 09/17/03 07:46 PM Re: The death of a very loose grounded conductor!  
Gus1999  Offline
Member
Joined: Dec 2002
Posts: 24
Los Angeles, CA, USA
Why was the ground carrying current? or did this happen during a ground to hot fault?


#104643 - 09/17/03 09:24 PM Re: The death of a very loose grounded conductor!  
ThinkGood  Offline
Member
Joined: Aug 2002
Posts: 1,081
Milwaukee, WI
Gus1999:

See 2002 NEC, Article 100, Definitions:

Grounded Conductor. A system or circuit conductor that is intentionally grounded.

a/k/a "neutral"

Grounding Conductor. A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes.

It appears that the green is from oxidation (or is that oxidization)?

[This message has been edited by ThinkGood (edited 09-17-2003).]


#104644 - 09/17/03 09:35 PM Re: The death of a very loose grounded conductor!  
SvenNYC  Offline
Member
Joined: Aug 2002
Posts: 1,691
New York City
Two wires per terminal lug? I think that's a no-no!

What's the deal with that thin wire next to the fat white one going to the first screw? It looks like it's totally bare.

It certainly looks to me like the wire that still has its insulation semi-intact is green....

Someone got their colors mixed up? Plugged a neutral into a grounding bus or vice versa?

Gross...


#104645 - 09/18/03 09:54 AM Re: The death of a very loose grounded conductor!  
Zapped  Offline
Member
Joined: Oct 2002
Posts: 482
Huntington Beach, CA, USA
Joe,

I'm with Gus...why was this conductor carrying current? Was this the result of fault elsewhere in the (poorly installed) system?


#104646 - 09/18/03 10:53 AM Re: The death of a very loose grounded conductor!  
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
Gentlemen:

I didn't take the picture, but the Electrical Inspector who did, told me that the connection was loose and that the load, whatever it was, caused the wire to burn up.

This would be a typical situation at any termination not tightened properly.

Please take a 2-wire circuit under a load such as a lamp with a large bulb, and use your amprobe to see if the white wire is carrying any current .... I will await for your reply, and if you can send the picture I will post it here.

I am unable to do this now because I don't have an amprobe and I am in a hotel meeting room.

I always challenge my students, asking if they want to take odds that the "neutral" in any panel, were the load is unbalanced will produce a voltage.


Joe Tedesco, NEC Consultant

#104647 - 09/18/03 04:28 PM Re: The death of a very loose grounded conductor!  
rmiell  Offline
Member
Joined: Nov 2000
Posts: 242
La Junta, Co. USA
Just guessing, but it looks like someone terminated 2 conductors under one screw, with one of those conductors the equipment grounding conductor, and one the grounded (neutral) conducotr. This is verified by the set just above the damaged set.

Even if this panel had identified the terminals as being ok for more than one conducotr, the more than one conductor would still have to be only equipment grounding conductors, never the grounded.

Now the problem. Due to the loose screw, there was arcing due to the load, then overheating of that conductor, then insulation failure.

Solution? Shoot the guy who did it? Na, he just didn't know (how many of us did this in the past, before getting an education here on this forum, or other ways!!!). Cut back the neutral to a point where the insulation is not damaged, splice a new piece in, and terminate it correctly.

Rick


#104648 - 09/18/03 09:20 PM Re: The death of a very loose grounded conductor!  
ThinkGood  Offline
Member
Joined: Aug 2002
Posts: 1,081
Milwaukee, WI
Is that conductor nicked?

[Linked Image]



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