Electrical issue - Main breaker keeps tripping, Sub panel is not

[anomale]

Hello, I have a 40A dual pole 240v breaker at the main panel that runs to a sub panel by the pool. There is a 20A dual pole 240v breaker for my pump and for an intermec timer that switches on and off my swg at the pool sub panel. Came out this AM and found the 40A breaker tripped. the 20A sub panel wasn't The pool equipment is the only thing connected to the 40A main breaker.

I reset the 40A and turned the pump on (Intermec SWG was off). it ran for about 3 minutes then I heard a pop by the pool sub panel went to check it and the 20A breaker was not tripped (could have been the pool pump shutting off I don't know what the pop was). went to the main and the 40A was tripped again.

Assuming it's the pump, what would cause the 40A to trip at the main but not the 20A at the sub panel? There are 2 other 110 breakers in the pool sub panel one has a pool heater plugged into (it is off) and the other is going to an outlet that is not being used. Neither tripped but I haven't inspected them for shorts yet. assuming there is no issue with them. What should I look for or test to troubleshoot?

I tested the wiring from the pump to the breaker at the sub panel and no shorts or obvious issues. I also have an emporia monitor hooked up at the main panel 40A breaker and there were no current spikes, Pump was running steady at .200 watts before the breaker tripped.

 

[Jimrahbe]

A,

I assume these are NOT GFCI breakers.. If that is true, then I would suspect a bad main breaker.

Thanks,

Jim R.

 

[anomale]

correct not GFCI Is there a way to test the Main breaker?

 

[Jimrahbe]

Is there a way to test the Main breaker?

Not really, non GFCI breakers are pretty cheap..

Thanks,

Jim R.

 

[anomale]

I'll swap both out and see what happens

 

[JamesW]

I reset the 40A and turned the pump on (Intermec SWG was off). it ran for about 3 minutes then I heard a pop by the pool sub panel went to check it and the 20A breaker was not tripped (could have been the pool pump shutting off I don't know what the pop was).

If you heard a pop, it was probably a wire shorting to ground.

Open the subpanel and look for black burn marks.

Can you show pictures of the subpanel and breakers?

 

[generessler]

If you heard a pop, it was probably a wire shorting to ground.

+1. The 40A breaker would blow like this if the feed from the main panel down to the sub-panel has a short somewhere. The pop means there's something serious to get ironed out before trusting the equipment again.

 

[JamesW]

I think that the pool is over 40 years old.

If the subpanel is the original equipment, it is probably in poor condition.

 

[anomale]

Here are some pictures. I ohmed out each line and there were no shorts. I did not see any melted wires either.

If there was a short, I would expect to have seen a huge spike on my current meter at the main panel but there was none.

Note: There is a pigtail at the jbox that has no wires connected

 

[JamesW]

I ohmed out each line and there were no shorts.

Can you explain what you did?

Did you check the power wires to ground for continuity?

Do you know how to do this safely?

You can try a new breaker if you want.

 

[JamesW]

How old is everything?

The system looks old and it is difficult to follow everything with a bunch of disconnected wires etc.

 

[ajw22]

Is this burnt insulation and a bare wire?

 

[ajw22]

Note that you do not have a GFCI CB for your pump, which is required by the current code for safety.

A licensed electrician who installed your VS pump would have been required to install a GFCI CB with it.

Electrical GFCI - Further Reading

www.troublefreepool.com

 

[anomale]

Can you explain what you did?

Did you check the power wires to ground for continuity?

Do you know how to do this safely?

You can try a new breaker if you want.

Yep no issues working with electricity. here is an image of where I measured and the results with all the sub panel breakers removed

Black probe points - Open
Gray probe points - Open
Yellow probe points - 20 Ohms

I just removed the outlet and the ground wire is corroded so I'll be replacing that.

The system is pretty old i would guess 30 years, the disconnected wires were from a pump I installed but haven't used in a few years, they were in one of the breakers, I removed them to swap 20A breakers incase it was a bad breaker.

 

[anomale]

Is this burnt insulation and a bare wire?

View attachment 619438

no I just checked, it was some crud on there I scraped it off and the wire looks fine

 

[anomale]

Note that you do not have a GFCI CB for your pump, which is required by the current code for safety.

A licensed electrician who installed your VS pump would have been required to install a GFCI CB with it.

Electrical GFCI - Further Reading

www.troublefreepool.com

I installed the pump a few years ago, was unaware of the code, thanks for pointing that out. I'll grab a gfci breaker for it

 

[JamesW]

Yellow probe points - 20 Ohms

Yellow is Hot to Ground?

 

[anomale]

Yellow is Hot to Ground?

I believe that is neutral, you can see from the gfci breaker that the white spiraled wire is going to the yellow bus bar

 

[JamesW]

You should have 2 hot lines, 1 Neutral and 1 Ground.

Did you check from each Hot to Ground?

Did you check from Neutral to Ground?

 

[JamesW]

I believe that is neutral

Where is the other Hot?