On Jan 8, 2:14*pm, croy wrote:
Two years ago, I revamped a 20a circuit in my (USA) house. I
added some outlets, and put a GFCI breaker for that circuit
in the service panel.

All was well for a year and a half, then the GFCI breaker
started tripping for no apparent reason. *I assumed that the
breaker had gone bad, so I replaced it. *The new one still
trips, albeit after a longer period of time (old, about
three minutes; new, three to 20 hours).

I've pulled all the outlets and tightened the screws.

Still the breaker trips after some hours, whether the
circuit gets loaded or not.

One thought I've had: *the original romex for the longest
run of this circuit is from that period of time (1960s?)
when the ground wire is smaller gage than the main
conductors. *Could that be causing the problem?

Other ideas?

--
Thanks,
croy

The GFCI breaker works by detecting leakage current on the ground
wire. It only needs to detect about 5ma to cause a trip. Witth no
obvious problems they willl still trip just because the wire is too
long. This is caused by capacitive coupling between the hot wire and
the ground. I dis overed this the hard way when I ran an extension
courd from my back porch to my storage shed about 60 ft away. Forgot
and rediscoverd it again when I ran 100ft of extension cord at an RV
park.

Jimmie