Burning wire in quazite box

[Caruso Electrical Cont.]

This one really has me scratching my head. I opened a poorly installed ground box this winter to find burnt up #2 CU conductors, the insulation was literally melted off and the wires were charred together in some places. I dug the old box out, upsized to a new quazite box installed waterproof connectors and a few weeks later they said the parking lot lights are out. I opened the box and the insulation is back melted below the ground where it goes into conduit. Anyone see this before or have any recommendations?

 

[Coppersmith]

Sounds like one or more joints in that box are not tight and are arcing.

 

[ptonsparky]

Crimp splices and heat shrink are the only way to to on those. The gel filled wraps would be good, but pricey.

 

[Rock86]

This might sound silly and I am just spit balling here but... any chance of an oversized overcurrent protection? The #2 Cu should be able to handle parking lot lighting... but its a thought. Do you have a picture? I'm curious how much of the insulation is melting and where the char marks are occurring.

Again, just thinking... is the insulation rated for wet location?

 

[Dsg319]

This one really has me scratching my head. I opened a poorly installed ground box this winter to find burnt up #2 CU conductors, the insulation was literally melted off and the wires were charred together in some places. I dug the old box out, upsized to a new quazite box installed waterproof connectors and a few weeks later they said the parking lot lights are out. I opened the box and the insulation is back melted below the ground where it goes into conduit. Anyone see this before or have any recommendations?

Can you get estimated Distance and load current, and OCPD? And I’m guessing it’s pvc conduit?

 

[hillbilly1]

I would venture a guess this is 480 volts, and probably has insulation damage on the load side of the connection. Quite a bit of heat can be generated without the ocp tripping. That is one of the reasons GFP is used on larger 480 volt services. A high resistance arcing fault could exist causing the overheating. Lightning is good at blowing pinholes in the insulation, especially in the 90’s where it comes up. Water sitting in the quasite box can often be brought to a boil!