GFCI + Pigtail = Mystery

[Bacchus]

I believe the statement that the reverse Y will "never" work is not quite true. I carry one 50' 30 amp cord along with a smart reverse Y and have been able to get both legs to work using 2 different pedestals. I assume this is because it's using different neutrals. I have also come across a few marinas that understand the problem and have each pedestal wired with different legs on each side so the smart Y will work here also. I realize this is a bit cumbersome and not always possible but it has allowed us to run the AC in marinas with gfci and 30 amp only.

I'm no electrician so I'm not really sure how the magic works but it does.

It will work with out of phase 30A in an old marina but not with newer marina meeting current codes... big difference.
How could the Y adjust /;split the amps returning on the single ( 50A 125/250V) leg to the 2 30A 125V legs and match exactly the amps delivered from that recepticle? Possibly if everything is off and there is zero amps being drawn??? but once a load is applied the 125V hot and neutral will be unbalanced.
I have no interest in continuing any disagreement only trying to assist the OP answer his question. Only / best? Way it to find a friend / acquaintance with a 50A 125/250V pedestal and connect directly from pedestal to boat with a 50A cord while he is out of his slip... or haveva marina allow you to try connecting with a 50A cord.

 

[Clark]

Notes: 1) The reverse Y can never work if there is working ground fault sensing present on either of the 30A circuits. Technically, they are called EPD (equipment protection devices). It trips if the imbalance is more than 30ma. GFIs trip at around 5ma but the idea is the same. The reverse Y will work fine is one Y leg is on L1 and the other is L2 and both are without GF sensing.

2) The OP stated he had a 240V isolation transformer. They don't normally have a center tap connected to neutral on the primary side. If neutral comes aboard, it is usually not connected. Even if it was was, the current would all be flowing between L1 and L2 and not be returning to the one neutral and back out the other to balance the currents within 30 ma.

Think of the EPD breaker as a clamp on ammeter. For 30A, it clamps around hot and neutral and not ground. The resulting current fliwing in and out must be within 30 ma of canceling out to 0. For 50A, the clamp is around L1, L2 and neutral. If the current is flowing from L1 to L2, it cancels to 0 as in the 240V isolation transfomer or 240V load case. If is flows from L1 to N or L2 to N (or any combination), it again cancels to 0.

Consider two 30A EPD breakers with the isolation transformer or even a 240V load. Current flow from one EPD breaker but returns to the other one. Both are unbalanced and one if not both will trip. (It's a race.)

 

[ranger58sb]

I believe the statement that the reverse Y will "never" work is not quite true. I carry one 50' 30 amp cord along with a smart reverse Y and have been able to get both legs to work using 2 different pedestals. I assume this is because it's using different neutrals. I have also come across a few marinas that understand the problem and have each pedestal wired with different legs on each side so the smart Y will work here also. I realize this is a bit cumbersome and not always possible but it has allowed us to run the AC in marinas with gfci and 30 amp only.

That may be bypassing the part about trying a Reverse Y with new GFCI pedestals (the "never work" part)? Did those places have the new GFCI pedestals?

-Chris

 

[Clark]

Clarification: I am are not talking about convenience outlets with the GFI buttons, I am referring to new "to code" EPD 30A outlets.