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Small spark when bugging in.

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Last night I had an emergency meter socket replacement. I cut L1 and L2 and left the neutral tap in place. I replaced the meter socket and went to bug in.
As I was connecting the second leg I saw a small spark when I touched the line to the bug. I didn’t have the meter plugged in, obviously, so there should be no draw.
I removed my first bug and tested continuity on the upper service cable. It tested fine no continuity. So I was thinking maybe a small short on the upper service cable where voltage was needed. I connected one leg and tested and found 10 volts on the second unconnected leg. I tried to verify by testing with length of Romex and still got voltage on the 2nd (not connected to the utility) leg. the service cable goes from the back of the home to the front. Approximately 90 feet so I wanted to test before declaring the cable bad as the materials were not available at this point and the cost would be significant to the homeowner.
I made the taps with the service cables and with both legs connected had 240 volts between the 2 legs and 120 from each to neutral..
So I was thinking maybe the spark, it was small, was a potential difference and I only saw it because of how dark it was. I don’t want to assume this though. I explained to the homeowner what I saw and that I would be looking for an answer of how this could happen because if there is a verifiable risk the cable is unsafe it will need to be replaced.
Any thoughts on this would be appreciate.
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
You need to use a low impedance meter when checking voltage as you did.
I suspect the darkness is why you saw a spark at all. Conductors will act as a small capacitor when first connected.
You need a megger for a more definitive test of the cables condition. Hundreds of thousands of ohms vs the maybe 2000 ohms of your continuity tester.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Just the capacitance charging current for the cable that you are connected. It takes a very small amount of current and voltage to see a small spark. You can easily see one if you short out a standard AA battery.
 
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