Technical Close call in the shop last night

Right. An electrician buddy of mine told me the same. NEVER, EVER, daisy chain them, always tail them out in the box so that the rest of the devices on that run don't feed through.

 

In effect it’s wired in parallel, not series. If it was in series then two things plugged in at two different sockets and working at the same time, would only get 60 volts.

 

Depends if the outlet was pigtailed or run in series to the other, downstream outlets.

If it was pigtailed, you’re correct. There’s nothing drawing current, so no resistance and no heat.

If the downstream outlets are wired to the other terminals on the burned outlet, any current draw downstream will heat up a loose, high resistance terminal like that.

I pigtailed the circuit when I ran power the length of my lean to when I turned it to an extension of my shop. Didn’t know why, but your pictures make me understand. I just used the outlet as a pass through in the hundreds of circuits I had previously wired, and have found loose wires on occasion when rechecking my work.

 

I think when he said “wired in series “ he didn’t actually do that, just a misuse of a term.

Edit: “daisy chain” can appear to seem like it’s in series, but what happens it’s the conductor is feeding a parallel circuit. I’m sure he wired it correctly, or the first time two different recepticals were used at the same time, it would be evident.

 

I’m not sure, but maybe the 15amp backstab type outlets would actually be a safer alternative for general use on 15 amp circuits. That eliminated the loose connection possibility. Obviously not here, where the circuit and 12 gauge wire are required for 20 amp compatibility.

 

The outlets themselves are daisy chained in series, since if that burned wire had totally become an open circuit, all of the downstream outlets would be without power .

 

Sketch out what you said. Can’t have a circuit for plugs, lights, etc in series. The wire is point to point, but not in series with the receptacle that it’s fed from. It’s a parallel circuit

Edit: If a receptacle was wired in series (not sure how) 120 volts would be at the first “through” the second and so on down the line. That would mean everything that worked of the different plugs at the same time will share the voltage

 

I had a nail go through a wire after our house had been resided. It was a total accident and took about two months before everything went to shit and about Burnt the garage and house down. Scary situation for sure.

 

Never back stab any device. It's not worth the risk when done with duplex receptacles. The connection to the conductor inside the device is utterly inadequate. All new receptacles only have the means for a #14 to be stabbed in back. All #14 and #12 wiring should be spliced and tailed. The extra time it takes to do it right is worth the trouble. Again, I would highly recommend using an AFCI breaker or if the circuit is part of a 3 wire, an Arc Fault receptacle as the first receptacle in the circuit will be the best protection to have.

 

I had a similar near miss yesterday. Was bumping my engine over with the key to position the cam to check lifter clearance. Got to a stopping point and went to town to get a prescription for my wife and stopped by Panda Express for lunch. Moseyed back to the shop and opening the door was hit with a strong gasoline smell. Seems I had left the key on and the electric fuel pump was pumping away, Holley needle didn't seal properly and the floor was covered with a pool of gasoline!! Time to get my pressure shutoff switch function again. in the meantime am disconnecting wire to pump when bumping engine.

 

Yeah, if nothing was plugged into it that would be a daisy-chain failure. Daisy-chaining used to be legal but was banned years ago after too many issues like this. Pigtailing is the law of the land now. You should pig tail the ground also, not just the hot and neutral. The only receptacle you can 'feed through' is a GFCI rated for it.

Keep in mind there's also different quality/durability levels in receptacles. There's economy, residential, commercial specification (AKA spec) and hospital grades in ascending order of price and durability. Economy are the ones you'll see in the 'hardware' aisle at a grocery store (most won't have screws, are 'stab-in' only and may or may not be legal where you are; avoid them), residential is just what it seems. Economy will be 15A, residential could be either 15 or 20. The 15A residential grade is generally fine on a 20A circuit as long as it's pigtailed and it won't see heavy use or loads. A bit heavier use like kitchen counters or garages it's best to use 20A rated outlets, they'll last longer. Shop or workbench use, step up to 20A spec grade unless you're constantly plugging/unplugging into them then switch to hospital grade. Generally price will roughly double with each step up in grade, but it's been a long time since I priced them.

 

Yes, that's what happened.

This is gonna take a while to remedy. I have a TON of outlets. uess I better get cracking.

One more question: What would the correct size wire nut be for tying the 3, 12 gauge wires together?

 

One last thing... The reason they still have the four screws even though you shouldn't daisy chain them is to allow you to split the outlet. That small 'link' between the screws on each side can be removed, so you can have one half always hot and switch the other half or feed each half with separate circuits.

 

In your case a Ground Fault Circuit breaker would not have tripped either. You did not have a short to ground. What is now code is an AFCI or Arc Fault Circuit Interrupter . It senses the arc and will trip.

 

Hi Steve, you can also feed in and out of the Arc Fault receptacle. Pretty much everything is wired with Arc fault protection today as per the NEC.

 

Red if using Scotchloks, otherwise tans. I prefer the tans, they're less bulky.

 

Thanks. Parts ordered.

 

I noticed an outlet was warm when unplugging an extension cord. I turned the power off at the board and opened up the outlet, 2 of the screws, phase and earth weren't particularly tight. After tightening, then I checked all the other outlets and found 3 more that I had to tighten. 10 year old installation. I was very lucky, we are 240 volt down here too.

 

I had a GFI receptacle out on the deck do that as I was pushing the plug in. Burnt tip of my thumb.

 

If you look at any receptacle that has four screws (not counting ground), as in two on the hot side, and two on the neutral side, you will see that each pair is bonded by a VERY small strip of wire.

If you use a receptacle as a junction, whatever is downstream on that circuit drawing power is drawing it across those thin strips.

That strip exists ONLY to power the other socket in the same receptacle.

 

I’ve replaced most of my outlets and replaced the old cloth covered wire with 10-2 with a ground, although a few circuits that are single plugs or lights I did with 12-2 with ground. When I moved here, the whole house was powered through two 15 amp glass fuses! I replaced that crap with a 150 amp breaker box and split countless circuits that were all jumbled together.

 

Those were just coming in when I retired. I was told by a rep that those were invented primarily to prevent electric blanket fires...

 

I was told many years ago, to use only 12-2 with ground for outlets, and 14 gauge was only to be used on lighting circuits. My fuzzy memory thinks that may have been Ohio code at the time, but I'm not certain. I am certain that I still follow that rule to this day, and anytime I'm inside my breaker panel, I check all of the connections to see if they are tight. I also tend to think that the repeated heating and cooling may be responsible for connections becoming loose. I am very glad you had no fire there.

 

The other thought is the gauge of the extension cord and its length. I spent a lot of years in construction as a carpenter as well as running my hot rod shop. And the nightmares of overloaded extension cord on job sights was insane, the longer the cord and the smaller the cord, the more resistance and load you have. I have seen cords litterly melt. Of course, now days instead of having thousands of feet of cords running all over the site, you have 6 dozen battery chargers plugged into a temp service through countless power strips. The whole system is only as strong as its weakest link. Spend a day double checking your system and always side on over kill whenever possible. Be safe. Larry

 

w

X3 on this. My thought also was that he must have daisy chained the circuit for that recptacle to burn like that with nothing plugged into it.

 

Usually caused by a bad connection/termination, when overloads happen the majority of the time the neutral cable/connection fails, if it was me I would check all connections involved with any equipment wired up by whoever connected that power point.

 

I am going to start building the pig tails as mentioned. I figure I might as well change out all of the 15A outlets to 20A while I am doing it. Are these what I need?

 

Or the good old Stab-Loks....

 

Should be fine, you don't need to use tamper resistant on old work.

 

It is now, but not in the past. Old 12 may be white also.