Need help in troubleshooting the following: Outdoor circuit from GCI receptacle to light switch (for pool light), on to two receptacles, all wiring between each is buried 12/2 w/g UF. When powered up, GFCI trips but after 15 sec to 5 minutes. I have isolated the fault to the wires between the switch and receptacle, but am perplexed as to why the delay in tripping the GFCI. Would a nick in the neutral insulation be causing this?