Motor Feeder - Cracked Electrical Cable

[MrJLH]

:blink:Had a pump trip out yesterday. Opened the NEMA 7/9 enclosure and found significant damage to the feeder cable at the breaker connections. Is this a cause of the enclosure getting too hot? Typically we run this pump right at FLA. Any ideas?

 

[infinity]

If the conductors are the proper size then I would guess that it's terminal failure likely due to improper torque.

 

[ramsy]

My Money is on undersized wire, overheated wire terminations.

Everyone forgets the motor load adjustment x 1.25

 

[Jraef]

Usually if the terminations over heat, there is significant discoloration and evidence of thermal damage to the breaker. I don’t see that here.

There is something odd about those cables though. It almost looks like the insulation was taped on and it’s the tape that is failing. Maybe it’s just my old eyes on a small phone screen though b

 

[MattS87]

Usually if the terminations over heat, there is significant discoloration and evidence of thermal damage to the breaker. I don’t see that here.

There is something odd about those cables though. It almost looks like the insulation was taped on and it’s the tape that is failing. Maybe it’s just my old eyes on a small phone screen though b

And is it just me or does B phase appear to be aluminum while A and C are copper?
Never mind I think its just dust (some on top of breaker as well)

 

[ActionDave]

My Money is on undersized wire, overheated wire terminations.

Everyone forgets the motor load adjustment x 1.25

It's required to upsize circiut coductors 1.25%. I have not found undersizing to be a problem.

I have no idea what a motor load adjustment is.

 

[ptonsparky]

I’ve seen that type of damage on older thwn. The outer jacket would crack like that esp when cold at installation. Do a FOP or scan it with a thermal to check for poor connections.

 

[Cow]

I see this fairly regularly.

Replace the breaker and the wire and you'll be good to go.

 

[sameguy]

B phase has a problem looks like oxidation, look at the phase tape the pipe is a chimney for the heat; as said need to calculate load/wire size and ir and amp check .

 

[mbrooke]

As 2 others have pointed out, B phase looks like its been over heating.

 

[MrJLH]

And is it just me or does B phase appear to be aluminum while A and C are copper?
Never mind I think its just dust (some on top of breaker as well)

All the wires are copper. The conductor is just that discolored

 

[MattS87]

All the wires are copper. The conductor is just that discolored

Have you had a chance to do an amp draw or IR scan on this with the pump running?

 

[MrJLH]

Have you had a chance to do an amp draw or IR scan on this with the pump running?

Unfortunately no, our facility does not perform I/R scans in Nema 7/9 enclosures on a program type basis. I have been pushing this though.

however, I did find a photo of the breaker from last year around this time and there was no apparent cracking in the cables.

 

[MrJLH]

I see this fairly regularly.

Replace the breaker and the wire and you'll be good to go.

Replacing the feeder and starter assembly this week! Will post how it went.