Insulation Breakdown of Polaris Splice

[djr3203]

I just ran by an issue where I have a 3phase, 100A disconnect feeding (2) 3phase, 50A disconnects that serve electric space heaters. The load side of the disconnect has (3) #2AWG feeding into a wire gutter where Polaris splices were used to splice down to (2) 50A feeders at #8AWG each going to their respective conduit and disconnect within 10' of the splice.

The splice kit on all three phases has overheated and broken down the insulation of the wires and splice. I measured the amps on all three phases and I was reading from 69A-72A on each phase, well within the ampacity of the wires. The splice blocks were stacked pretty close together.

Could the overheating be due to the proximity of the splices to each other? All the connections appear to be good, so I don't think it is from a bad connection.

Could the heating be associated with inductive heating? I thought the closer the phase conductors are the better it is to limit inductive heating?

DJR

 

[waross]

An inexperienced installer did not tighten the splices properly.
Try this:
Put a 7 strand #8 cable into a set screw type terminal lug.
Tighten the set screw as much as you like. Pull straight on the cable to prove that the set screw is tight.
Give the cable a slight twist in the direction to take the twist out of the strands. Or twist the cable a couple of times in each direction.
Now the cable will drop easily out of the connector.
An experienced installer will tighten the set screw and then twist the cable back and forth and then re-tighten the set screw. This may be repeated two or three times.
If the splice connector is only tightened once, there is a good possibility that the movement of pushing the splice into the wire gutter may loosen the connection.
I have seen this too many times.


Bill
--------------------
"Why not the best?"
Jimmy Carter