dimbulb
New member
- Location
- Ruffs Dale, PA USA
The following problem has recently surfaced and has me scratching my head. This 20A circuit utilizes 12-2 romex, has two 70W dusk to dawn lamps and a liftmaster garage door opener. It is fed from a 20A Siemens single pole breaker located within a 200A sub-panel. With exception of one short segment, all romex is visible (but undamaged). This circuit has functioned as intended since 2003, up until a week ago.
The breaker only trips when the dusk to dawn lamps are active, but it can immediately be reset and may remain live for 1 to 24 hours before tripping again. I unplugged the door operator and switched off one light, and the breaker eventually tripped. Switched off that lamp and turned the other on. Again, the breaker eventually tripped. Tried a spare breaker with same result.
There is a junction box with three outputs from the panel feed -a branch for one lamp, a branch with the second lamp and the door operator, and a third branch leading about 75' to an outdoor receptacle and another indoor receptacle. Isolating the three and connecting each in turn, the longer run ONLY shows +/- 130ma with my Fluke inserted between the breaker and the feed, and the breaker on. Also, a test lamp glows when connected instead of the meter. Disconnecting the neutral gives the same result.
I found nothing abnormal inside any boxes, and no damaged insulation anywhere. With all the receptacles removed from the longer branch, Fluke readings don't change.
What am I missing, and what other tests do you suggest?
I have reconnected the two lamp circuits but not the longer branch and plan to monitor this evening when the lamps come on.
The breaker only trips when the dusk to dawn lamps are active, but it can immediately be reset and may remain live for 1 to 24 hours before tripping again. I unplugged the door operator and switched off one light, and the breaker eventually tripped. Switched off that lamp and turned the other on. Again, the breaker eventually tripped. Tried a spare breaker with same result.
There is a junction box with three outputs from the panel feed -a branch for one lamp, a branch with the second lamp and the door operator, and a third branch leading about 75' to an outdoor receptacle and another indoor receptacle. Isolating the three and connecting each in turn, the longer run ONLY shows +/- 130ma with my Fluke inserted between the breaker and the feed, and the breaker on. Also, a test lamp glows when connected instead of the meter. Disconnecting the neutral gives the same result.
I found nothing abnormal inside any boxes, and no damaged insulation anywhere. With all the receptacles removed from the longer branch, Fluke readings don't change.
What am I missing, and what other tests do you suggest?
I have reconnected the two lamp circuits but not the longer branch and plan to monitor this evening when the lamps come on.
