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#43328 10/10/04 10:13 PM
Joined: Jan 2003
Posts: 21
R
rj Offline OP
Member
This might be a dum question and it mighthave been asked before, but here goes. Why does the nuetral always seem to burn? Me and the guys I work with have all wondered why this happens. Thanks for any information that you can give me.

#43329 10/10/04 10:18 PM
Joined: Nov 2002
Posts: 267
W
Member
First thing that comes to mind is unbalanced load. Second, the old edison wiring method on 3-ph systems where they shared 3 hots of a, b & c phase and used one nuetral.

#43330 10/10/04 10:44 PM
Joined: Feb 2003
Posts: 939
F
Member
the same thing with multicircuit single phase also when someone is not too bright with L-N-L set up and when the load get uneven it will actally over heat too and once a while i will see the diy's do put the breaker on wrong leg and end up burn the netural wire pretty bad i did see it happend few places it is no fun to fix it right


merci, marc


Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)

#43331 10/11/04 02:09 AM
Joined: Jul 2002
Posts: 8,407
Likes: 2
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Quote
First thing that comes to mind is unbalanced load.
I'd second that!. [Linked Image]
Neutrals in 3 phase wye systems carry the (usually minimal) out-of-balance current and unless there is a gross imbalance of the loads, shouldn't usually be a problem.
However, one situation where I have seen a Neutral get so hot the PVC insulation melted off it, was where an Electrician used a Neutral that was only half the size that it should have been, in a 3wire 230 system over here. [Linked Image]

[This message has been edited by Trumpy (edited 10-11-2004).]

#43332 10/11/04 06:17 AM
Joined: Feb 2004
Posts: 62
S
Member
Computers and other non-linear loads add to neutral overheating. any circuit that will have a lot of electronics need it own neutral. The other problem that I have found is loose connections at the neutral bar due to more than one wire under the screw.

#43333 10/11/04 10:49 AM
Joined: Nov 2000
Posts: 2,148
R
Member
Quote
Computers and other non-linear loads add to neutral overheating.
Only on three phase wye systems. The neutral problem with nonlinear loads does not happen on single phase 120/240 volt three wire systems.
Don


Don(resqcapt19)
#43334 10/11/04 10:12 PM
Joined: Sep 2004
Posts: 86
N
Member
You will usually find this situation when someone has relocated breakers in a panel and now have both circuits on a three wire circuit on the same leg in the panel. Instead of the neutral carrying the difference between the two circuits now it is additive. If you have two 20 amp breakers the neutral could concievably carry 40 amps, hence the burnt or discolored neutral wire. And as Stevemc stated, it is caused by loose connections at the neutral bar. I make it a habit that whenever I open a customers panel I tighten all connections. Takes a minute and if they are there it leaves an impression.
Ron


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