Sleeping on it, the obvious occurred to me: It is still two GFI circuits. GE panel. No such thing as a tandem GFI. Yet. Siemens approaches the question with their tandem AFCI. GFCI in the wings? Who knows. I will ponder on, and the inspector will have ethe final say. Thanks all.
I think his issue with the two pole is that he ends up with a 240 volt circuit which negates the 12" burial depth in T300.5.
I would say that only applies if an MWBC is run. If it's two separate circuits, each with its own neutral, that's two 120V circuits, regardless of the voltage present between the ungrounded conductors of the two different circuits. So I'd say 2 single pole GFCIs without regard to which leg they are on is fine.
But that brings us back to 225.30. It's a catch-22.
Sure, but that problem already exists in the first sentence of the OP, and is independent of the issues around having multiple Table 300.5 Column 4 circuits in the same conduit.
As stated that's your opinion. IMO the reason that they want to keep it at no more than 120 volts with GFCI protection is incase someone hits it with a shovel.
Given the definition of "voltage of a circuit," the only way for there to be a problem is if you consider the 4 conductors (A, B, Na, Nb), where loads are only connected A-Na and B-Nb, to be one circuit. Do you consider that one circuit? It's obviously two circuits, and each circuit is by the definition only 120V.
You might be right, but they didn't write Table 300.5 in that fashion. We know the CMPs can generate language regarding the maximum voltage between conductors of possibly different circuits, see 404.8(B). They didn't do that here.
I agree it makes sense that this is the intent, and before this thread that's how I always read the table.
I cannot say for sure but I think that if went back to the history of how the 12" minimum was written into the table in column 4 it would have something to do with a 120 volt limit for safety.
Looking at the old NECs on nfpa.org, the 1987 NEC doesn't have a table in 300.5, just a list of depths based on wiring method with a long list of exceptions. Exception #4 permitted "residential branch circuits rated 300V or less" and protected at 30A or less to have only 12" of cover. No GFCI requirement.
Can't use a 2-pole per the 300.5 limitation (no 240v cirs), or this is how I read it.
I could do the two blanks, with a bit of extra work, off a tandem. This may be the best approach to the inspector. I will write him soon with the couple of options (tandem, then 2 blank GFIs, or two GFI breakers with a universal hold down to lock them from being moved into a 240v additive arrangement by a future worker, messing up the intention of 300.5)
The intention of 300.5 is that you look at each circuit, determine the voltage of that circuit, and check if it is 120V or less. Comparing voltages across circuits is not in the wording.
Nor does it mention a quantity (limit).
I don't see how it matters that much. A 240v circuit is still 120v to ground. If you hit it with a shovel you could get 240v across the shovel, but a person would still likely get a 120v shock. In most failures, it seems like the shock risk is 120v. You would have to touch both ungrounded conductors to get a 240v shock.
And the opposition is saying "It certainly makes no sense that two 120V circuits on separate breakers should be subject to a different rule here than one 120 circuit."
