I turned off ALL circuit breakers in the panel.
I then pulled out the duplex receptacle from the electrical box in my garage and removed the wires.
I then attached the black, white and ground wires to a new duplex receptacle with two USB ports.
I was shocked by another white electrical wire in the box. Why wasn't that circuit controlled by a circuit breaker in the panel? Should the white wire have power?
Sounds like a problem with the neutral not being properly grounded and possibly a neutral that has a bad connection too. Even with the breakers open, your neutral is still connected to the service neutral and hence tied into the system that includes your neighbors, etc. Suggest you call an electrician. What kind of shock was it? The just noticeable little tingle kind or something more?
When I was trying to connect two white wires with a wire-nut (i.e., twist-on connector), one of the white wires sparked when it touched the other white wire.
Trader is right, you may have a problem with the building grounding or neutral wiring. Theoretically if the last time the neutral was grounded was at the service disconnect and it goes unshared from there to your unit, there should be no voltage there with all of your breakers off but if there was some connection of neutrals between units down stream of the service disconnect you can see a voltage there. It should be very small tho. You might also have the problem that "ground" in your panel may not be ground everywhere. There are typically voltage gradients between what we call ground in different places.
It could just be that the neutral is sharing two hots. If you get between two white wires you complete the circuit. Was there a red wire coming in and leaving the box?
A wing of garages are detached from the condos.
When the condos were built in the early 1970s, the farthest garage from my condo was assigned to me and the nearest garage was assigned to my neighbor.
When I complained about that, the condo board re-assigned the garages so my garage is now closest to my condo. The condo board also had to switch the electrical service (to match the new arrangement).
Could the "sparking" white wire still be controlled by my neighbor's circuit panel?
The new receptacle with the USB ports won't fit into the existing junction box because the new receptacle is deeper than the old receptacle and the box is crammed with too many wires. I'll have to replace the old box with a larger box.
Yes, agree. That new info puts new light on it and points the finger elsewhere. If there is voltage between those two segments of his neutral on one circuit, it strongly suggests that it's being shared with a neighbor. What's on that circuit? I'd be focused on things like exterior security lighting and the like, where it's more likely to wind up with two hots incorrectly sharing a single neutral. Measuring the current would be interesting too.
But he has the disconnect open, so that neutral would not only be sharing a hot which is a code violation, but it would also be sharing a neighbor's hot on a different service.
Sounds like you're on the right track. Perhaps something got screwed up when they switched the electrical service. They could have just moved the hot connection from your unit to the other guy, but not the neutral. That would produce the symptom. But they must have moved the hot, I'm assuming you checked that it's dead with your service disconnect open?
Evidently the power is NOT from your breaker box. There was a mistake made when the condo was built
Correct the above to be that the neutral could be shared if it's an Edison circuit and correctly identified/tied, but again that would not exhibit the voltage there with the disconnect open. Something is wrong.
I would look for something like this.
condo owner posted for all of us...
Not to criticize but testing the wires should have been done before work, be that is at may there is definitely a problem probably caused by the garage swap. Also the overstuffed box points to this.
If a USB receptacle won't fit, if it were me, I'd just forget about it. Not sure why he needs a USB charging receptacle in a condo garage.
The headlight, the tail-light and the speedometer on my bicycle are USB rechargeable.
Since I keep the bicycle in my garage -- doesn't everyone? -- having a receptacle with USB ports in my garage seems sensible.
I see, sounds like a good reason, hope you can make it fit.
Charge your phone while wrenching on your Hardley Abelson?
If this is in a common area it is probably on the "house" panel.
Put a wiremold ring on it.
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