Issues with Dual Function Breakers on 120/208 commercial panels

[synchro]

Does public safety personel with two way radios ever enter the buildings?

Thats an interesting question because just about all personnel here have hi band radios, its how we operate. Could that affect the breakers in some negative radio? thanks

The RF from the two way radios could get rectified by semiconductor junctions in the DF breaker, and this could conceivably cause it to trip. If you want, you might key up a 2-way radio near a 2-wire extension cord that's plugged into a receptacle to see if it would cause a DF breaker to trip.

You might try putting a ferrite toroid on the pair of hot and neutral output wires from the dual function breaker that 's tripping in the empty room.

The toroid at the first link below would introduce a common-mode impedance to reduce interference at High Band (i.e., around 150 MHz). The one at the second link would work better for lower frequency interference. You could try both.
If you have enough slack, have the hot & neutral pair make one loop around the toroid to increase the impedance. Otherwise, just pass the pair through the opening.

https://www.digikey.com/en/products/detail/kemet/ESD-R-25D/4290919

https://www.digikey.com/en/products/detail/kemet/ESD-R-25/4290918

 

[jim dungar]

He has a 368FC, I believe thats the meter to have for this kinda issue:

Yes, this particular meter is intended for leakage currents. My comment was more for general information. Many people think all clamp-ons can read really small currents.

 

[tortuga]

The 30ma (Class B) breaker is a easier cheaper test for a field electrician, as that is a very quick test to see if you have a serious ground fault >30ma or a possible nuisance trip >5ma - 30ma.

 

[ptonsparky]

30 mA breakers would be special order and significantly more expensive in my area.

 

[ActionDave]

More expensive than a new Fluke 368?

 

[ptonsparky]

More expensive than a new Fluke 368?

Less expensive than multiple brands of gfci.

 

[HertzGood85]

For some reason I thought the load side of GFCI protected circuits were supposed to be in separate raceways or cables from non protected. I may have to do some digging

I have not heard that one but everything is ran in either emt or mc in this facility so that would be a hard fix to make.

 

[HertzGood85]

Usually those type of places are wired in MC, but I don’t think the op has specified. Many years ago I troubleshot an assisted living complex when they first came out with arc faults. Panelboards were full of them. Each breaker put out enough heat from the breakers that the panel cover was almost too hot to touch. Siemens paid us to replace all of them, never heard anymore about it. A lot of wasted 12-3 mc on that job, the pm and foreman didn’t realize they required separate neutrals.

That is really bad when you get that kind of heat from a breaker, i do notice that these dual function breakers seem to run kind of warm all the time. I don't know if thats common but it makes me think there is alot more going on in there than in just a single function breaker which i dont really like.

 

[HertzGood85]

You have the best tool for the job as it can detect "complex, non-sinusoidal waveforms" so no matter how that 4-6ma is happing you should be able to see it with the meter.
I am wondering how are you taking the leakage current readings with the 368FC?
I'd replace the breaker with a standard 20A breaker (or a 30ma breaker if you have to leave it)
Set the fluke 368FC measure (log) the 'max' current 'imbalance'.
View attachment 2571338
Then clamp both the hot and neutral
View attachment 2571337
You should see an 'event' over 4ma.

I'd bring a standard plain old 20A breaker, a GFCI breaker as well as a 30ma 'GFPE' (class b) GFCI for that panel just to eliminate possibilities and study the issue.I

I have been taking measurements with the clamp around the hot and nuetral at the end of circuit and at the breaker and im always getting around .7 mA leakage current. or so it says.

 

[tortuga]

Less expensive than multiple brands of gfci.

I picked up the ones I got off ebay, and the only ones I have needed so far are just plug on interchangeable load-centers.
Here is two for less than 50 bucks shipped to your door:

Siemens QE120 Industrial Control System for sale online | eBay

Find many great new & used options and get the best deals for Siemens QE120 Industrial Control System at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[tortuga]

I have been taking measurements with the clamp around the hot and nuetral at the end of circuit and at the breaker and im always getting around .7 mA leakage current. or so it says.

Ok thats correct, Are you setting it to 'log' so it can record a trip event?

 

[tortuga]

Here is a SQ D bolt on class B gfci breaker:

Square D QOB120EPD Industrial Control System for sale online | eBay

Find many great new & used options and get the best deals for Square D QOB120EPD Industrial Control System at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[ptonsparky]

Here is a SQ D bolt on class B gfci breaker:

Square D QOB120EPD Industrial Control System for sale online | eBay

Find many great new & used options and get the best deals for Square D QOB120EPD Industrial Control System at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Nice finds. I almost never think of buying from other than my local suppliers.

I picked up the ones I got off ebay, and the only ones I have needed so far are just plug on interchangeable load-centers.
Here is two for less than 50 bucks shipped to your door:

Siemens QE120 Industrial Control System for sale online | eBay

Find many great new & used options and get the best deals for Siemens QE120 Industrial Control System at the best online prices at eBay! Free shipping for many products!

www.ebay.com

View attachment 2571352

 

[kwired]

Here is a SQ D bolt on class B gfci breaker:

Square D QOB120EPD Industrial Control System for sale online | eBay

Find many great new & used options and get the best deals for Square D QOB120EPD Industrial Control System at the best online prices at eBay! Free shipping for many products!

www.ebay.com

If I needed just one I'd probably try Ebay first. I remember asking a price at supply house for the plug on version probably at least 15 or so years ago and seems it was over $200 then, likely even higher today. And they would have needed to order from Square D as well as they had none in stock.

 

[ptonsparky]

I still like the Fluke Megger and 368.

 

[tortuga]

The thing I like about the class B GFCI breaker is its a easily explainable test and easily reproduced by say an appliance vendor.
I can say "I tested it on a 30ma breaker thats 5X less sensitive than a GFCI and it still tripped when the compressor started"...

 

[synchro]

Can you disconnect both the hot and neutral wires from the output of a breaker that is having issues on an empty room, and then see if that breaker will ever trip?

I have not tried that. If an unwired breaker doesn't trip that would indicate that breakers is bad correct?

If an unwired breaker trips it could indicate a bad breaker, or at least one that is more sensitive to voltage spikes on the panel bus or other power quality issues.

If the DF breaker does not trip when both the hot and neutral wires are disconnected from its output, a suggestion is to try it with only the neutral wire connected. Then if it starts tripping, something other than current leakage from hot to ground must be causing the tripping.

 

[Jim_SWFL]

It sounds like you believe some of the same breakers are tripping and others are not. This being the case, you think a portion of the batch might be bad. Did you try swapping one of those problem breakers with one that has not tripped? I'd want to know if the problem follows the breaker or stays with the circuit wiring.

In an unoccupied room, is it possible to isolate the receptacle wiring from the homerun back to the panel?

Since you question the stab-in connections, why not change them in one or two rooms as a test? I think these could cause trouble, but I don't see them as a culprit for a GF trip.

Leakage is cumulative. Having the GF protection at each outlet gives you the 5mA limit per receptacle. The breaker is now measuring the combined leakage for the entire circuit against a 5mA limit. We usually opt for GF protection at the outlet and only use breaker GFCI if the outlet is not accessible, or the device is hardwired on a dedicated circuit.

I tend to agree with previous posts that mixed neutrals, and possibly some unintentional neutral to ground connections are worthy of your attention.

I'd also want to make up a plug with a known amount of leakage as suggested by Tortuga to see how the Fluke measures that leakage when connected on a circuit. If you made up a few of them with varying resistance, you could plug them in individually, and then in combination to force a trip and a measurement. For example, one of them generates 1mA, another generates 2mA, and the last one 3mA.