fluctuating current

[JdoubleU]

I went to troubleshoot a lighting problem and need some advice. About 5 can lights are dimming every once in awhile for a length of time of about 15 min. I went to the panel and found the breaker. The voltage was ok and the current seemed normal. I checked the phase conductors feeding the panel. The voltage seemed fine on all the phases, but the current on phase B was all over the place ranging from 38 to 58 to 0. The fluctuation of current was rapid. This panel is a three phase 120\208. What do you think this problem is? I am going to hook up a power phase analyzer next.

 

[bphgravity]

Is there a large load like an RTU served by the same panelboard that kicks on during the length of time that lights appeared to be dimmed?

 

[quogueelectric]

I went to troubleshoot a lighting problem and need some advice. About 5 can lights are dimming every once in awhile for a length of time of about 15 min. I went to the panel and found the breaker. The voltage was ok and the current seemed normal. I checked the phase conductors feeding the panel. The voltage seemed fine on all the phases, but the current on phase B was all over the place ranging from 38 to 58 to 0. The fluctuation of current was rapid. This panel is a three phase 120\208. What do you think this problem is? I am going to hook up a power phase analyzer next.

Did you check to see that the wire was tight under the breaker. The next question is it a mwbc?? and the next question is it sounds like a loose or bad neutral in either the mwbc or more likely on the aluminum service latteral/xformer. If the current is not stable the voltage cannot be stable either and must be tested under a load. If your voltage swings are only on one phase it will probably a lug burning up somewhere on a line. If the volt is unstable on all 3 phases it is probably a neutral burning up somewhere.