Backfeeding Subpanel Problem

[JtheSwissArmyKnife]

First-timer for this forum.
My team and I installed this system in September 2024.
Just finished a $10k warranty and need to answers to make sure this dam well never happens again…
It seems the combination of appliances has a default of 200-500 milivolts being back-fed and trips the gfci breaker.
With the last cold snap (January of 2025) the 50 amp double-pole gfci flipped without apparent cause. It services the PoolSide Tech, Jandy variable-speed, Raypak E3T, CMP (UV/Ozoneator), and the Intermatic 300 powering the 1/2” colorlogic 80.
After having replaced all impacted plumbing, it appears the Poolside tech and the Intermatic are incapable to allow the independent gfci breakers to function, they do function with standard breakers though. (Concerning… )
I have scoured the entire system. I replaced the 50 amp gfci with a standard and installed separate gfci’s for all appliances. Had 2 different electricians look at it. I pulled all the wires out of the conduit hoping for a jacket breach on the lines/loads.
The most rational thing I can come up with is that the step-down transformers for the Poolside Tech and Intermatic have a slight feedback causing the dripping gfci.
Please give me your input.
Thank you in advance.

Jim

 

[ajw22]

Welcome to TFP.

With the seperate GFCI breakers which breaker trips?

Show us pictures of the breaker panel and wiring.

 

[ajw22]

What model GFCI CBs have been used?

A Class A GFCI trips when the current to ground has a value in the range of 4mA to 6 mA (reference UL 943).

Individual devices can have loss of 1-3 ma and not trip the GFCI. If multiple devices are connected to one circuit then the loss is cumulative. The GFCI can trip with cumulative loss of over 6 ma although no one device has a problem.

That is why it is best to put devices on dedicated GFCI circuits.

Electrical GFCI - Further Reading

www.troublefreepool.com

 

[JtheSwissArmyKnife]

Thank you for the responses.
Attached are a few photos of the wirings…
@ajw22, the lights and PoolSide Assistant both immediately trip the gfci, but not the standard breakers.
#1 Intermatic 300w transformer
#2 Subpanel (top/left is pump, bottom/left is CMP, top/right is heater, second to bottom/right is PoolSide Assistant. Bottom/right is 12v transformer)

 

[ajw22]

the lights and PoolSide Assistant both immediately trip the gfci, but not the standard breakers.

That is usually caused by the neutrals being connected to the neutral bar instead of to the GFCI CB.

Which CB is tripping?

I don’t see any GFCI CBs with neutrals connected.

 

[ajw22]

The 120V CBs are not GFCI so where are the lights and controller connected to?

 

[JtheSwissArmyKnife]

To maintain operation, (client is out of town) I removed the gfci on the assistant and transformer and temporarily installed regular breakers

 

[ajw22]

To maintain operation, (client is out of town) I removed the gfci on the assistant and transformer and temporarily installed regular breakers

Show us the wiring when you put in the GFCI CB.

The controller should not require GFCI and low voltage lights connected to a transformer may not either.

 

[JtheSwissArmyKnife]

I recognize I’m not an electrician, so my game here is not to pretend to be one. Haha
in a brief study of my Klein “cheat sheet” for VA, it seems it isn’t necessary, but certainly not discouraged for all appliances to be under gfci protection within a spa/pool setting.
This project was the first iteration of product-line by the spa manufacturer. They’ve been incredibly patient and supportive of my learning curve throughout.

The thought-process in removing the 50amp double pole gfci and installing standard 50amp CB and individual gfci CB for all appliances was: the whole system went off-line without notice, 5 months into the life of the system, client was out of town, and no-one knew it wasn’t working until 2 weeks had gone by. All pipes above-ground froze and burst. Had to replace all the pertinent plumbing and 2 of the appliances.
Maybe, just maybe it was the pump or heater that pulled the original 50amp gfci CB, if it goes again, it wont take the control panel with it and the error messages will go through, alerting my team about the issue.

 

[ajw22]

Having multiple devices on one GFCI circuit make it difficult to determine which device is causing the GFCI trip.

You also do not want controller that don’t need GFCI protection having another reason to go offline.

You should implement a fault tolerant design.

 

[JamesW]

It seems the combination of appliances has a default of 200-500 milivolts being back-fed and trips the gfci breaker.

measured how and by who?

Had 2 different electricians look at it.

What was their opinion?

Master electricians, Journeyman or Apprentice?

Have you called Poolside Tech?

 

[JtheSwissArmyKnife]

Feeling quite dumb at the moment.

Thank you for the responses.
Attached are a few photos of the wirings…
@ajw22, the lights and PoolSide Assistant both immediately trip the gfci, but not the standard breakers.
#1 Intermatic 300w transformer
#2 Subpanel (top/left is pump, bottom/left is CMP, top/right is heater, second to bottom/right is PoolSide Assistant. Bottom/right is 12v transformer)

Update on the pilgrimage of self discovery of how dull my walnut of a brain can be…
The pump, heater, and CMP unit don’t have neutrals, though the Poolside Assistant/controller and the transformer do. When the gfci was to be installed, the wiring was incorrect and the neutrals for the transformer and controller were tied to the neutral bus and the pigtail of the gfci CB tied to the same bus. This would indeed, result in an immediate trip of the gfci CB for both.
Solution:
#1. Don’t be an Rear and assume wiring schematics are correct on appliances/trust blindly trust what I’ve been told
#2. Reinstall the gfci CB with the proper neutral placement. (i.e. connect the neutral from transformer/controller to the gfci CB, tie pigtail, as before, to the neutral bus)

 

[JamesW]

Variable speed pumps can cause noise in the wiring that can trip a gfci.

The Siemens GFCI breakers are more resistant to false tripping.

Why was it a warranty claim?

The single GFCI is not the best choice for the installation, but I don't think that you would necessarily be liable to pay for the freeze damage.

Warranty covers defects in materials and labor.

If an electrician wired everything, then why is it not their fault?

 

[veraj]

Feeling quite dumb at the moment.

Update on the pilgrimage of self discovery of how dull my walnut of a brain can be…
The pump, heater, and CMP unit don’t have neutrals, though the Poolside Assistant/controller and the transformer do. When the gfci was to be installed, the wiring was incorrect and the neutrals for the transformer and controller were tied to the neutral bus and the pigtail of the gfci CB tied to the same bus. This would indeed, result in an immediate trip of the gfci CB for both.
Solution:
#1. Don’t be an Rear and assume wiring schematics are correct on appliances/trust blindly trust what I’ve been told
#2. Reinstall the gfci CB with the proper neutral placement. (i.e. connect the neutral from transformer/controller to the gfci CB, tie pigtail, as before, to the neutral bus)

If the load is using neutral (110V), it needs to come from the GFCI breaker load neutral. 220V circuits don't use neutral, and in this case, the load neutral from GFCI is not needed to be connected. Pig tail from GFCI breaker should always go to neutral bar. If you have false trips due to noise, then using Sieman's breaker is the recommended approach.

 

[RKE_CA]

First: Not an electrician
Second: Not directly related to your issue
Third: Electricians are telling me this information, I may have mixed it up, so take it with a grain of salt.
Fourth: As mentioned earlier, don't trust schematics or what you are told. Start from square one and question everything along the way.

In the 90s, I was working in technology and we had strange things happening on our computer screens. Alpha characters on the computer screens would change or disappear. We thought it might be a virus, it was not. Tested the computers in the technology offices (another building) and they worked fine. Turned out several workers in the rooms where the problems were happening had space heaters under their desks which caused variations in the voltage on the line as they would switch on and off. Since this was an older building and an older main transformer, which wasn't designed for the load, the lower voltage to the computers caused issues. So, check the total load on the main panel and the load at the pool equipment panel.

Same place, slightly different issue, we had wavy computer screens. Turned out to be EMF (ElectroMagnetic Fields) causing the problems. A previous electrician decided water pipes would make a good ground for a new circuit, and there was EMF on the water pipes going through the foundation radiating enough to cause the computer screens to be wavy. So, check that the ground is correct.