Yes but the current of the branch circuit feeding multiple pigtailed devices is supplied from line side of GFCI or top receptacle rather than bottom load side receptacle of GFCI. Does top GFCI not check for imbalance between its hot wire and neutral wire connections?
Line side of the device will only feed the device that's why it was mentioned before.
Let's pause on this real quick: IF this was an issue in a dwelling unit, then I would agree with @ptonsparky since 210.8(a)(6) specifies that a GFCI must be installed in "Kitchens - where receptacles are installed to serve the countertop surfaces". Since the fridge is not on the countertop, and 422.5(a) does not require a fridge to have GFCI protection, I would serve it first with a non-GFCI receptacle, then at the next kitchen circuit, start your GFCI protection. This is based on 2017 and 2020 codes. But since this is a non-dwelling environment, code wording forces your hand here. Not helping your situation, but should this happen to someone in a dwelling unit, I've done it this way in the past and inspectors have accepted it.
GFCI protection of the refrigerator receptacle in a dwelling unit is often triggered by list item 7.
How far back towards the utility transformer do you think it should monitor?
If the secondary of the isolation transformer that the fridge is connected to is galvanically isolated from the GFCI (i.e. not an autotransformer), current leaking to the chassis of the fridge would be balanced at the secondary coil of the isolation transformer.
I guess how ever far the imbalance can be sensed on grounded conductor neutral
Yes ok I got yea
It doesn't go backwards. In practice and in theory. It measure at the line side of the device what is going through the face and load side. If there is a load before the cts never know anything is different.
Ok thanks will look into this more
Very few devices work upstream on anything. Surge arrestor technically work anywhere but closes to the transformer will work best. A GFI is a switch the switch is controlled by the circuit inside. The point it gets its baseline from is the line terminals. It's like 0ing out a scale.
Yes, that interrupts leakage current path that is a result of high frequencies produced by these drives. My guess is by design they figure that motor frame is shielded by the appliance outer shell, when you take the cover off you expose it, so they close the switch and bond that motor frame, which will allow the leakage to have a current path.
The GFCI only monitors what passes through it, connecting an incoming line and an outgoing line to only the "line" terminals doesn't pass any current through the GFCI, it just uses the line terminals as a splice point. One may do this if they want/need GFCI protection only on that one receptacle, anything else on the circuit is not GFCI protected.
Then fix the refrigerator if it still trips after you have replaced the GFCI!
