Why are these wires overheating?

[tonype]

Saw this in a building that I inspected for a buyer today. 225-amp panel (Square D). Installed and approved by the AHJ in 1997. The right side grounding and neutral busbar contains many charred wire ends and conductors :shock: :shock: . The busbar on the other side appeared ok. Power was off to the building so I could not take any infrared readings. What is possibly the cause of this (I would also think that this is a potential fire hazard)?

Regards,
Tony Shupenko

 

[celtic]

Were the connections tight?

 

[petersonra]

hard to tell.

my guess is the panel is a replacement for one that had some kind of electrical fire in it previously and they reused some of the old wires.

IMO, infrared readings are pretty meaningless unless you have some baseline to compare them to.

 

[tonype]

I do not monkey around in the panel, so I do not know if the connections were tight. However, it appears that most, if not all, of the wires contain evidence of heat damage. I would guess that the temperature would have to be pretty darn high to cause the damage - that was why I would have used the IR thermometer, if I could.

Anyway, is there some reasonable explanation why this was only on the one side of the panel?

I am going to call it a defect and advise the client to hire a licensed electrical contractor to trouble-shoot.

Regards,
Tony

 

[infinity]

My guess is that they're shared neutrals from multiwire branch circuits with the phase conductors connected to the same phase. This is causing the neutral current to become additive and therefore the neutrals are overloaded. You need to trace back the neutral to see if it's derived from a cable(s) with red, black and white conductors.

 

[tonype]

Couple of items- there was no evidence of any fire in the basement. SOme of the wiring is newer - circa 1997. The place (vacant) once contained a tanning salon business, with (2), 40-amp, 220-volt circuits for tanning beds. Could this somehow be a factor?

Regards,
Tony

 

[realolman]

If the entire right side buss bar was loose from the neutral connection would it get hot enough to melt all the wires like that?

Maybe there's a screw or two loose in the back of the bussbar that connects it to the ...uh... bussbar that connects both sides to the neutral service conductor

 

[charlie tuna]

i would guess that the added loads were not properly phased --- like two tanning bed circuits supplied from "A" phase connected to the same neutral --- total load on the neutral could be fourty amps or more!!

 

[dlhoule]

I doubt that it would have been caused by tanning beds. Ones I have seen have had both A & B lines run to each bed. I think Tony Shupenko made the right call. Get a qualified EC in to check it out. Can't tell a whole lot from pictures. I am guessing from damage to a couple of screw heads that improper tools was used for terminations and probably not properly torqued.

 

[tjmicsak]

Looks like for whatever reason, they just couldn't get the screws tight enough and even stripped the slots in doing so. Wonder if the screws match the bar and are long enough to torque down tight on the wire.
Or maybe over torqued and loose ends altogether.

 

[tonyi]

I've seen wires almost severed and hanging by a sliver of metal by people who used the "grunt method".

 

[mario]

it seems funny to me that no one has noticed that there are neuts and grounds on the same buss bar ... that ain't right is it ...

 

[don_resqcapt19]

it seems funny to me that no one has noticed that there are neuts and grounds on the same buss bar ... that ain't right is it ...

No problem if the panel has the service disconnect in it.
Don