Solve This Service Call

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Little Bill said:
Need more info. Did the 3-way switch, or wiring there of, have anything to do with the problem?
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No. It was just the HO showing off his new fancy tester that he thought the red light meant that's where the problem is. The red light simply indicated the presence of voltage.

Little Bill said:
I would find out what was on the circuit that trips the main when the breaker for that circuit is turned on.
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It was marked "Kitchen hall bath basement lights"

Little Bill said:
Unless the main isn't breaking contact on both legs, how is "half the house" going off?
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"Half the house" going off is simply the HO being confused.
 
480sparky said:
So how would you diagnosis this?
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Use solenoid tester to determine which black is the feed in, use that to identify the rest of the blacks.

Remember, I said that when we were under the impression that the 3-way is what turned off half of the house.
 
LarryFine said:
Use solenoid tester to determine which black is the feed in, use that to identify the rest of the blacks.

Remember, I said that when we were under the impression that the 3-way is what turned off half of the house.
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OP said the 3-way (and assoc. wiring) didn't have anything to do with the problem.
 
I'm going with open neutral on a MWBC that was not put on a proper 2 pole breaker or did not use handle ties. I would look at all devices that were listed on breaker 14 and see if any are newer smart device switches that require a neutral and see if the HO made a crummy splice to the neutral and it pulled out. I would also ask the customer what doesn't work when breaker 14 is off and what doesn't work when you turn breaker 14 on.

EDIT: if its a newer house. It probably has romex. If it is a MWBC it might be on 3 wire romex and I can see what other circuit is using the same neutral by removing the cover on the panel. If so shut off that breaker and open up all boxes related to what doesn't currently have power.
 
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I would turn off all other single pole breakers, the see if turning on #14 still trips the main.
If the main does hold I would then start turning on the single pole breakers until you find the one that causes the main to trip again.
 
NCVT indication near a wall switch often means the yoke isn't connected to the EGC and is capacitively coupling the yoke to indicate it is "hot".

Used to have inspectors wave them past every switch when doing a final inspection, any of them having indication means we will be taking the plate off and checking grounding connections. Only had one time where a luminaire tested this way yet was bonded well, no idea why it set his tester off.
 
sw_ross said:
I would turn off all other single pole breakers, the see if turning on #14 still trips the main.
If the main does hold I would then start turning on the single pole breakers until you find the one that causes the main to trip again.
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If turning on the 15a breaker in space 14 trips the main, I assumed there was a dead short between that and a circuit that was on the other leg in the panel. So I got the Fluke out and clipped one lead to the neutral bar and the other onto the terminal of the turned-off breaker. It read 122.4 volts.
 
480sparky said:
If turning on the 15a breaker in space 14 trips the main, I assumed there was a dead short between that and a circuit that was on the other leg in the panel. So I got the Fluke out and clipped one lead to the neutral bar and the other onto the terminal of the turned-off breaker. It read 122.4 volts.
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What about to the can? I would say can not bonded, circuit 14 is shorted to can by the connector or other means, grounds are on separate ground bar bonded to the can, miswire some where (probably by the HO trying to make it work)
Connecting circuit #14 to a opposite leg breaker. (Assuming the panel is service equipment)
 
hillbilly1 said:
What about to the can? I would say can not bonded, circuit 14 is shorted to can by the connector or other means, grounds are on separate ground bar bonded to the can, miswire some where (probably by the HO trying to make it work)
Connecting circuit #14 to a opposite leg breaker. (Assuming the panel is service equipment)
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The fact that everything works, even with one breaker turned off, is a big clue.
 
Time to insert a high-wattage bulb in series with the offending breaker to act as a combination current-limiter and indicator.
 
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