A 60 amp breaker in our circuit breaker box serves a sub-panel in our barn. That panel serves 5 120 volt lighting and convenience circuits. The sub-panel has two bus bars, each attached to one phase of the buried 240 volt cable from the house, which consists of three separate conductors (two hot and one neutral)in a trench. For the first two years or so of operation, both phases of the drop were energized. Now, for some unknown reason, only the breakers connected to one bus bar are energized. I can find no problems with any connections so must assume that one conductor of the buried cable is broken. I have two questions. First, is there some way to definitively confirm that a break is the problem? Second, if it is, how can I determine where along the 80 feet or so of cable the break has occurred?
Electrical – Troubleshooting dropped phase in 240 volt line
electrical distributiontroubleshooting
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Best Answer
To determine if there is a break.
If the test shows open (no continuity), then there's a break in one of the lines. If not, then something else is wrong.
If the lines test as not broken, test for continuity through the feeder breaker.
If they both show voltage, the breaker is not the problem. If either does not show voltage, replace the breaker.
If the lines do test as broken. You can either dig them up and look for the damage, replace them (abandoning the existing cable), or contact a local Electrician to see if they can locate the break for you.