[bdmeyer]

I have a new construction house that was just finished in February of 2020. The builder is very helpful in getting anything fixed I uncover.
I’m 60, have owned six houses have a bit of an electronics background and have always installed ceiling fans in all my houses.
Against proper safety procedures, instead of turning off the circuit breaker for the ceiling light fixture, I tape the light switches down in the off position and use a voltage tester before I start messing with the bare wires after removing the existing fixture.

On the first ceiling fan in this house, when I removed the existing fixture, as I moved the wires apart after removing the wire nuts, the circuit breaker blew.
I didn’t feel anything, and didn’t think I had actually touched exposed wire other than the copper wire without insulation.

I reset the breaker, and tested with a volt meter.
I got voltage, but very low. My thoughts were it must be phantom voltage induced by parallel wiring.
As I moved the wires again, the circuit breaker blew again.

I called the builder who sent the electrician out to see what was going on.

He came out when I was at work, and my wife said, he told her `found a wire that may have been cut too short and was pressing against the light switch mounting box.'

He also hung the ceiling fan for me. (No charge)

How Nice. Now I wonder if he did that so I couldn't easily test if it was still happening.

I went to install a ceiling fan in another room this past weekend and had the same experience.

My voltage tester (The pencil shaped item that beeps and turns red on the end when near voltage) goes off on the white and copper wire, but only when touching them with the light switch turned off,

I would like your advice on how to proceed. Could the very low voltage I detect actually just be phantom induced voltage? Why would the breaker trip when moving wires that appear to be in perfect shape, with insulation etc?

Should I hire an electrician to inspect my house wiring, or are there safe tests I can perform myself first, look at wiring in poanel box etc?

Thanks for any advice folks.

 

[CodeMatters]

Is this an AFCI breaker? If so it's likely that you're tripping due to GFI fault
(which they also detect).
If it is an AFCI, start by learning how your particular brand identifies the type
of trip. Manual may have been left on top of the panel, and if not, can be found
online.

 

[anyacolo]

as I moved the wires apart after removing the wire nuts, the circuit breaker blew.

I reset the breaker, and tested with a volt meter.

As I moved the wires again, the circuit breaker blew again.

why do you keep turning the circuit breaker back on while working on the wiring?


why didn't you just leave it off after it blew the first time? :confused1:

 

[udraft]

Hard to say without more detail, but some ceiling fixtures are wired with a single conductor for switched and an always hot conductor thru the box. (I'm not an electrician, so I'm likely using the wrong terms)

I too have ceiling fans all over the place, my 2 downstairs bedrooms are like this, it's really nice. The fan works with the pull chain and the light works with the switch, totally independent.
So turn off the breaker, wire it up, then check it out. (Of course that bit about a too short wire grounding against a box is just scary)

 

[daveb1]

You really need to rethink your safety procedures. If the power is coming to the light first, then taping the switch in the off position will NOT protect you.

 

[HandyAndyInNC]

Use an actual ohm meter and not a dumb pen when testing electricity. How do you know it is low voltage? That pen will not tell you this.



Seems to me there is an issue with the insulation already bare and touching the box. Or there is no box connector. Poor quality installation. Simply touching two wires together that have already been touching under the wire nut, will not cause a short.

 

[bdmeyer]

I'll check this when I get home. based on what I read about AFCI, it is required by code since 1999, so I will 'assume' for the moment that it is.

 

[bdmeyer]

Is this an AFCI breaker? If so it's likely that you're tripping due to GFI fault
(which they also detect).
If it is an AFCI, start by learning how your particular brand identifies the type
of trip. Manual may have been left on top of the panel, and if not, can be found
online.

I'll check this when I get home. based on what I read about AFCI, it is required by code since 1999, so I will 'assume' for the moment that it is.

 

[bdmeyer]

why do you keep turning the circuit breaker back on while working on the wiring?


why didn't you just leave it off after it blew the first time? :confused1:

Troubleshooting, trying to determine which wire(s) caused and wanted to measure actual voltage present to the ligh, with the switch off.

 

[bdmeyer]

You really need to rethink your safety procedures. If the power is coming to the light first, then taping the switch in the off position will NOT protect you.

Interesting. Before I begn, I turned the light switch off, and the light itself turned off. I thought this indicated that there is no power running to the light.

 

[bdmeyer]

Use an actual ohm meter and not a dumb pen when testing electricity. How do you know it is low voltage? That pen will not tell you this.



Seems to me there is an issue with the insulation already bare and touching the box. Or there is no box connector. Poor quality installation. Simply touching two wires together that have already been touching under the wire nut, will not cause a short.

I used the pen voltage detector to see if there was any voltage at all. Once it lit up I used a multimeter (as explained in the original post) to see how much voltage.

I didn't touch any wires together, let alone wire that were touching under a wire nut. I moved two wires, one without any insulation,white and copper I think, when the breaker tripped. The other 4 with insulation., (I think it was five total, there is a switch for light and a seperate one for the fan)

 

[anyacolo]

Interesting. Before I begn, I turned the light switch off, and the light itself turned off. I thought this indicated that there is no power running to the light.

it does mean there is no power running to the light,


but there could still be live power in that same box

 

[chetwisner]

If the feed is to the light first, there will always be power there. The power will run though the light box down to the switch, and back up to the light. This way, the switch will interrupt the circuit from completing to the light, but it will still be live in hte light box.

A good tip is seeing a black and white wire nutted together inside the light housing.

Always shut off the breaker, NOT just the switch.

 

[seharper]

Such a new house surely has AFCI and/or GFCI breakers. So this went one of two ways.

If power came to the switch and only switched power goes to the light, then what happened is you flashed neutral to ground. This meant that current from other loads on the circuit now had an alternate path back to the panel. Some current took that path (current on multiple paths flows in proportion to their conductance=1/resistance). That tripped either the GFCI, or the parallel portion of a CAFCI.

If the power came to the lamp and had a switch loop, then when you were separating the neutral wires to remove the light/add the fan, you severed neutral flow to appliances downline on the circuit, which would give a small blue flash. It would also make electrical noise which "sounds" exactly like the "crinkle crunch" you have heard if you ever hooked up speakers with the amp turned on. It's literally that. That is what the series portion of a CAFCI listens for, so it would trip.