Fire in the shop, well almost.

[capncarl]

I've been noticing an occasional whisp of something burning in the shop but could never locate it and just thought it must be something outside. Today I went to start up the dust collector and nothing, nothing on that wall would power up. It's all on one breaker with 1 GFCI receptical protecting it all. The GFCI would not reset so I opened up the receptical and found the burned out receptical. It is melted down on the hot load side so there is not much investigating to do here. I have 3 new spares so I installed a new one, and found the problem. The new recepticals are push in the wire and screw types, but it doesn't really tighten the wire and allows the wire to twist with ease in the connection and will even allow the wire to pull out with minimum effort. What a piece of crap, all 3 spares do the same thing. I found that I could put a slight upward bend in the wire and put upward pressure on the wire when I install it and tighten it and it won't move. Everything is checked out and running now but I'll not install the cover on the receptical on it so I can keep my eye on it.
Other than being a poorly engineered fastener the GFCI did its job. At least the shop didn't burn down.

[dbhost]

FWIW, I always wrap and screw the wires to the reciptacle (I can never spell that) posts. I am paranoid about just that thing happeneing. It takes a bit longer, but the time is cheap insurance.

[mpc]

Is the wire the correct gauge for the receptacle? It sounds like the wire is smaller in diameter than what the screw terminals expect. Are the screw terminals designed for aluminum wire perchance? I think aluminum wire is typically thicker than copper wire for the same amperage rating.

Just some ideas. Double-check the wire gauge is enough for the circuit breaker amperage. Though "poorly engineering" or "cheap" receptacle is probably the real answer.

mpc

[JimD]

FWIW, I always wrap and screw the wires to the reciptacle (I can never spell that) posts. I am paranoid about just that thing happeneing. It takes a bit longer, but the time is cheap insurance.

+1 Last year I did the finish on about 800 Ft2 of addition we had put on and I wrapped every screw. Once you get the hang of it, it doesn't take long at all.

[Hellrazor]

Wrapping the screws is pointless when using a plastic box.

[JoeyGee]

FWIW, I always wrap and screw the wires to the reciptacle (I can never spell that) posts. I am paranoid about just that thing happeneing. It takes a bit longer, but the time is cheap insurance.

I'm confused on this, I can't picture what you're talking about.

[cwsmith]

I'm not sure either, but I'm thinking that "wrapping" is where you wrap a layer or two of electrical tape around the back of the receptacle to cover the terminal screws. I do that, as it covers the contacts. While it might be argued that for plastic boxes it's superfluous, I'm more inclined to think that it protects exposure to the contacts when the cover is removed.

It looks like copper wire, so not sure about the mention of aluminum. I don't use aluminum wire for anything, not even sure if you can buy it here in NY, as I think it's against code for anything but very heavy power feeds to a service panel.

This receptacle looks like the wire was pressed into the back, rather than bent around the terminal screws. The top brass screw isn't clear though. I do not use the 'press-in' terminals on the back of the receptacle. To me, they simple do not offer a proper contact. All the contact that you get there is the very edge of the contact spring, which isn't very much, and to me, that is a point of resistance and possible over-heating or arching under load. (I had a friend who took an electricians course at the local community college and the instructor warned against using these press-in terminals.)

Though more time consuming it is always better to form a hook on the wire and fasten it on the terminal screw, in a clockwise fashion... that screw on top, facing the camera appears to be either pressed in from the back (now exposed because of melting) OR, it was retained counter-clockwise on the terminal screw. The problem with fastening CCW is that the tightening of the screw can actually back the wire off the terminal.

Lastly, I think you have to be careful with the quality of the receptacles that are used. There's always been some really cheaply made products out there. Electrical switches, receptacles, and wire are no where to cut costs. Ensure that it is UL approved. Likewise, I really don't like using 14-gauge wire. Probably overkill, but I much prefer 12 gauge. It not only offers better load margin, but also is less like to break if bent to often. I noticed when upgrading the wire in this old house that working with the older 14 gauge, you have to be very careful as it easily snaps off, leaving you with a major task when working with a short lead barely extending from an ancient box. Running into a few of those, led me to rewire a majority of the circuits here. I think it is very important to consider using 12-gauge if your tool or appliance is running 12-15 amps on a continuous basis. Just too close to the limit rating of 14-gauge (while I know there's a margin, but why push it). The advantage of using all 12-gauge is that you can easily upgrade the circuit to 20 amps without having to strip or run new heavier wire. Also, make sure your receptacles are rated higher too.

CWS

[Black walnut]

Scary for sure; glad no fire happened.

[capncarl]

I wired the shop 7 yrs ago using only 12-2 with ground romex copper. This is the only GFCI duplex receptacle that I used although I bought 6. I can't remember why only installed 1 but at my other shop I had them in every circuit and they kept breaking every time they were used, so that is probably why I didn't use them in the other circuits. This circuit is the most loaded circuit in the shop with the dust collector, band saw, belt/disk sander and and miter saw on it. The dust collector and miter saw would be the 2 biggest loads on it at one time and neither of them would start at the same time.
Wrapping, like dbhost says, would have prevented this problem, but it is a pain to do on 12 ga wire. I believe I will go back today and wrap the load wires around the screws and be done with this problem. It may be time to go back and pull every receptacle out and re-tighten the screws. You would have thought that for a device like this receptacle a push in wiring connection wouldn't have been an option on the load side, although the instruction sheet does give the twisted wire option.
As you can see I provided plenty of circuits for the shop with some of them dedicated to one receptacle, just to keep out of this kind of problem.
The possibility of fire in the shop has always worried me, especially after I built the shop using OSB sheathing on the outside wall (under hardie plank), OSB inside wall sheathing and plywood ceiling sheathing. No drywall anywhere to act as a fire stop. Not that drywall would have preventived a fire in this instance. Welding in the shop is something I don't like to do because it doesn't matter how careful you are you will burn the epoxy floors so any time I weld with the MIG I pull the cords and machine on the driveway in front of the shop but sometimes I do crank up the gas welder/torch inside the shop for really small stuff. At night when I lock up the shop I usually do a walk thru and check everything to make sure it is unplugged. Only the AC, battery chargers and sometimes the air filters are left running.
capncarl

[LCHIEN]

I'm confused on this, I can't picture what you're talking about.

THis is what they mean by wrapping: Wrapping the wire around the screw and under the head for most of the circumference. And tightening the screw.



As opposed to using the spring tension terminals on the back of the receptacle.

[capncarl]

For this particular receptacle it is nearly impossible to wrap the wire around the screw. The connector screw is in a recess area and The screw is loose in the fixture, it will not come all the way out and it likes to flop back in the recess. There is just barely enough room for the wire to go around the head of the screw because of the plastic recess hole. It is almost a 3 handed job.
I was able to wrap both of the load wires and put it back together without using all my select words though.
Now I think I will work on getting a timer for my battery charging station so they won't set there and cook.
capncarl

[cwsmith]

Thanks for the post Loring,

I've never heard the term "wrapping", though I did find one old reference that said the wire should be "wrapped" around the terminal screw. While I don't hang around many electricians, the term that I grew up with (ancient) was simply that the wire should be looped or hooked around the screw. Either way, it's always been instructed as a 'clockwise' method.

At least NOW, I know what the term means.

Thanks,

CWS

[JoeyGee]

Ahhh...makes sense. I missed the part about using the push in the back part. I've only seen outlets with both the terminal screw and the option to push in the back. I've always been warned against the "push in", so I've avoided using those.

Thanks for the clarification.

[nwhomesteader]

Pretty sure most guys will tell you not to use the push in connector portion of those receptacles. They aren't secure and don't make enough contact with your wire which could cause arcing.

You should make a u shape in the stripped portion or your wire, unscrew the terminal all the way, place the straight portion of the wire in the terminal and pull the wire back until the u part seats onto the shaft of the screw then tighten.

Sent from my SM-T800 using Tapatalk

[capncarl]

This particular GFCI receptical push in wire connection is one that you must tighten the side screw to grip the wire, not the spring grip type. It just doesn't grip the wire very well. Hope we all learn from near misses like this one!
capncarl