troubleshooting...

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journeyman0217

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philadelphia,pa
ran into this problem today was wondering if anyone could lend some advice...There are 16 pendant lights in a local shop, all 16 light up when switch is thrown but the last 6 were noticeably dimmer than the others. I read 125 volts at fixture 1, 124 volts at fixture number 10 and read 25 volts on 11,12,13,14,15 and 16 ( the fixtures that were dim). any ideas?
 
High resistance connection somewhere between no 10 and 11. Or grounded conductor is open somewhere after no 10 but does have a high resistance fault to ground.
 
journeyman0217 said:
I was thinking maybe mc connector can be tighten to much possibly causing high resistance connection....?
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Not unless it has severed the mc jacket and has made contact with neutral conductor.
But I would be looking at wirenut connections first.....especially jam packed junction boxes.
 
mopowr steve said:
Not unless it has severed the mc jacket and has made contact with neutral conductor.
But I would be looking at wirenut connections first.....especially jam packed junction boxes.
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Would have to sever the neutral conductor as well, pinching into the ungrounded conductor would result in high current and tripping overcurrent device unless there is poor grounding/bonding, but then shock hazards would increase.
 
kwired said:
High resistance connection somewhere between no 10 and 11. Or grounded conductor is open somewhere after no 10 but does have a high resistance fault to ground.
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I agree -- the poor connection is at #10 or #11. Your voltage readings don't tell us what you are measuring to. . . is it the neutral conductor (white) or is it the EGC - equipment grounding conductor (the MC sheath / green)?

Assuming the voltage measurement is between energized conductor and EGC, remake the energized splices in #10 and #11.
 
High resistance connection equal heat! Consider the voltage droop and the resulting heating watts. It is best to locate and resolve the problem. P(in watts)=I x V. If you have a 90v loltage drop and a given current supplying those dimmed lights the result is the heating watts a the defective connection which is a serious issue.
 
templdl said:
High resistance connection equal heat! Consider the voltage droop and the resulting heating watts. It is best to locate and resolve the problem. P(in watts)=I x V. If you have a 90v loltage drop and a given current supplying those dimmed lights the result is the heating watts a the defective connection which is a serious issue.
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Yep. that failing connection probably won't be too hard to find, look for the toasted insulation on the conductors near the connection.
 
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