I just helped my friend change an outlet in the garage of a home he just moved into. The outlet was an old duplex that I replaced for a GFCI. The installation went fine, outlet tested properly and we used it to power several power tools and shop lights around the garage. The problems started when we went to plug in the post lamp that is located in a garden bed right next to the garage door and has a 12/2 direct burial conductor running from the post through a hole in the floor. The previous owner put a two prong non-grounded connector (I know, going to change that) on the end of the conductor. Now when we plug in the lamp it comes on, no issues except for the fact that after being on for about 10-15secs the GFCI cuts out. If we unplug the lamp, the outlet will reset and remain on until we plug in the lamp again. I didn't have my multi meter on me so I couldn't check but from what I described. Being that there wasn't a ground on the lamp connection...Would you assume the connection somewhere between the connector and the post lamp is having a:
- Line to ground short (going to GRN at the post or in the earth) where its causing an imbalance on the return (neutral) which would explain the delay in the GFCI turning off?
- Neutral to ground with a similar situation as the above scenario?
If so would doing a resistance check with my DVOM figure that out? Any other ideas? Thanks