Dodged a bullet in the shop. Heard crackling and had some power fluctuations. Wires wrapped around the posts were close enough to arc. Ran inside, killed the breaker and opened the outlet to find this. Job was done by a pro and he did a great job with the other 99% of it. This could’ve burned down everything. Shop is only about 10 feet from the house and the freakin propane tanks.

Two gang box and arced to hot on adjacent receptacle?

The two wires wrapped around the posts on that side were close enough to arc.

Two things that I noticed ... one is that the wire "J" hook should be going clockwise and not counter-clockwise and second the un-used screw should be tightened all the way in if not used.

The screws on the same side are connected unless you break off that brass tab between them. The wires' proximity to each other is 0 cause for concern.

The issue looks like the one screw was loose.

quote:

Originally posted by old dino:
Two things that I noticed ... one is that the wire "J" hook should be going clockwise and not counter-clockwise and second the un-used screw should be tightened all the way in if not used.

Both screws had a wire in them.

^^^
That's why I asked. Two neutrals would not matter if they touch. Arcing due to insufficient contact and/or loose connections. I have seen load on one receptacle arc to neutral on an adjacent receptacle in multiple gang boxes when they are too close, or not tightened and cord gets pulled/pushed causing the receptacles to come into contact with each other.

That's why AFCI Circuit Breakers (Arc Fault Circuit Interrupters) are required by code in bedroom circuits.

And why I loath "backstabbing" electricians.


Good on you for quickly disconnecting power when you did, Leemur.

For those that need an understanding of what a backstabbing electrician is - me - this link explains a lot. Sig Forum is a wonderful classroom.

https://boards.straightdope.co...al-outlets/580187/10

Loose neutrals are the most dangerous electrical mistake. Luckily it usually only melts outlet, or if crazy the box. Very rarely it can burn your whole house (shop) down. Good job hearing and addressing the situation.

Just to be safe I suggest spending an hour to check the rest. Turn circuit off. Pull outlets, give 1/4 turn on each screw, or whatever is necessary. That way you can sleep at night knowing you're safer.

Power fluctuations were a problem since it was wired. I plugged up something in every outlet in the shop and turned it all on, including a space heater. No fluctuations for the hour plus I was out there.

Power ain’t my thing. Just glad I was there when it started. God truly watches over children and fools.

Still would suggest tightening all connections or if uncomfortable with it or time doesn't allow, hire a pro to do it. It may be a waste of time/money, but it's worth it just in case.

what was plugged into the outlet at the time? Some kind of heater or maybe something else that draws a lot of amperage?

A miter saw that wasn’t in use.

quote:

Originally posted by radioman:
what was plugged into the outlet at the time?

Since the miter saw wasn't in use, while it was crackling, it wasn't what was plugged into this outlet... it was something being feed from it further down the circuit.

Would suggest you follow Skins' recommendation and physically check all screws on all outlets. If the electrician got one wrong, he may have gotten others wrong.

quote:

Originally posted by Excam_Man:

quote:

Originally posted by radioman:
what was plugged into the outlet at the time?

Since the miter saw wasn't in use, while it was crackling, it wasn't what was plugged into this outlet... it was something being feed from it further down the circuit.

^^^^ This ^^^^

What was plugged into the outlet boxes which are downstream of this failed outlet? Was there a tool or appliance which should have been pulling power at the time of the failure? If not, does that device have a grounded outlet? There is a chance that something was trying to find a path to neutral, perhaps an internal short on that device, if nothing was actually powered up or turned on. Not that this may have directly caused this issue, as the screw on terminal was evidently loose, but maybe something else going on as well?

I am not an electrical contractor, I only do electrical work for myself, so time spent on the job is not critical. Not that it would have prevented this issue, but as a habit I always wrap the outlets and switches with electrical tape after connecting the wires, before pushing them into the box. Keeps them covered to minimize chance of the bare copper neutral wire from coming in contact with the "hot" wire when pushing them into the box.

quote:

Originally posted by ensigmatic:
Would suggest you follow Skins' recommendation and physically check all screws on all outlets. If the electrician got one wrong, he may have gotten others wrong.

I’ll check before I power up anything again. The only things downstream of the outlet in question were a light and a space heater. Nothing was touching the ground wire, there was a wire connected to each post on the side in the pic and they had started to arc. The wire in the pic was loose enough that it could be moved by hand. My guess is that after having plugs inserted and removed enough, that top wire slipped down *just* enough to start arcing.

quote:

Originally posted by Leemur:

quote:

Originally posted by ensigmatic:
Would suggest you follow Skins' recommendation and physically check all screws on all outlets. If the electrician got one wrong, he may have gotten others wrong.

I’ll check before I power up anything again. The only things downstream of the outlet in question were a light and a space heater. Nothing was touching the ground wire, there was a wire connected to each post on the side in the pic and they had started to arc. The wire in the pic was loose enough that it could be moved by hand. My guess is that after having plugs inserted and removed enough, that top wire slipped down *just* enough to start arcing.

Was the space heater running at the time of the failure? If not, does the space heater use a grounded plug, with the third "ground" pin? Just curious.

quote:

Originally posted by Leemur:
The only things downstream of the outlet in question were a light and a space heater.

If the space heater was running at the time, it was the space heater that did it. Space heaters draw lots of power. The arcing you heard wasn't from that wire/terminal combination to the adjacent one. It was between that wire and its own terminal--due to the poor connection.

quote:

Originally posted by Skins2881:
Loose neutrals are the most dangerous electrical mistake.

Not just on outlets. Go into your breaker panel and use a long bladed insulated screwdriver to tighten down all the screws for neutrals and grounds on the bus bars. Do the same for each breaker with them shut off (of course).