Facts:
Inside a metal "quonset" shed.
200Amp panel .
A stomg of 6 outlets each,both walls, prof. installed, first outlet in string is GFCI protected. 12GA all in conduit, no visible damaage. Mounted on wood board fastened to metal shed wall.
Worked flawlessly for 20 years. 120 volt.
Past winter unplugged everything on east wall, wasn't using it.
This spring replugged drill press&light, tripped GFCI & breaker.
Reset, same tripping regardless of what I plug in.
Examination: no evidence of water, corrosion, mud dauber wasps,and no construction changes, new screws, no outside bldg work.
Disconnected string after outlet #3 isolating some of the string, no change, disconnect after #2, no change.
Installed new GFCI, no change.
Installed new breaker, no change.
I understand how GFCI sense differences in current in hot vs return wire. So is there something gone bad on on common (white) or grounding circuit? How? The GFCI trips sometimes w/o breaker tripping. All energizing shows 120volt+. Testing does not trip anything, but plugging in any load (like 60 watt) non grounded lamp, triggers GFCI.
Any thoughts on what to look for? And thanks for listening to my problem. Leo
Inside a metal "quonset" shed.
200Amp panel .
A stomg of 6 outlets each,both walls, prof. installed, first outlet in string is GFCI protected. 12GA all in conduit, no visible damaage. Mounted on wood board fastened to metal shed wall.
Worked flawlessly for 20 years. 120 volt.
Past winter unplugged everything on east wall, wasn't using it.
This spring replugged drill press&light, tripped GFCI & breaker.
Reset, same tripping regardless of what I plug in.
Examination: no evidence of water, corrosion, mud dauber wasps,and no construction changes, new screws, no outside bldg work.
Disconnected string after outlet #3 isolating some of the string, no change, disconnect after #2, no change.
Installed new GFCI, no change.
Installed new breaker, no change.
I understand how GFCI sense differences in current in hot vs return wire. So is there something gone bad on on common (white) or grounding circuit? How? The GFCI trips sometimes w/o breaker tripping. All energizing shows 120volt+. Testing does not trip anything, but plugging in any load (like 60 watt) non grounded lamp, triggers GFCI.
Any thoughts on what to look for? And thanks for listening to my problem. Leo