1970’s construction; steel boxes, wires in conduit, no separate ground wires.
Two outlet circuits in kitchen; circuit A with two outlets, one on each side of the sink; circuit B with one outlet 5′ from sink. They are on adjacent 20A breakers in the panel. Neither has a GFCI. Outlets are on pigtails. Both test properly wired using three-prong tester – two amber lights.
I installed a GFCI in circuit A with its dependent outlet on the load terminals; tested ok from both outlets.
I installed a GFCI in circuit B on the same pigtails as the old outlet; nothing on Load terminals. There are a hot, two lines branching out of the box into other conduits, and the pigtail all wire nutted together. The pigtail white and companion whites to the hot wires are wire nutted together. As soon as I turned the breaker back on, GFCI A tripped and could not be reset; GFCI B remained tripped and could not be reset. There was nothing plugged into either GFCI nor the dependent outlet on A.
When circuit breaker A is off, circuit B GFCI works normally. When breaker B is off, circuit A GFCI works normally.
All the outlets are Decora style, and there are GFCI’s in the bathrooms, so I’m guessing whoever upgraded from the original outlets found the same problem and couldn’t solve it so they just put standard outlets instead of GFCI’s in the Kitchen.
Anyone have an idea what’s haunting these circuits?