Burnt Receptacle...

[don_resqcapt19]

What makes you think it failed? I know I can burn a house down with a 5 amp resistive load. Even if the space heater was 10 amps, the resistance at the burnt receptacle could have very well added only a few more amps.

Adding resistance to a resistive load only acts to decrease the total current. There is no reason to expect an OCPD to open for these types of failures. The OCPD just sees current that is below the trip point and does nothing. Even the AFCI will not directly detect this type of heat producing problem. The AFCI only acts to open the circuit after the heat has caused the problem to progress from a poor connection to a ground fault of parallel arcing fault. If neither of these happen (unlikely, but possible) the AFCI will not act to open the circuit.

 

[peter d]

I ran into a simliar situation a while back where the neutral terminal was not tightened as the pic clearly shows this. Another reason I pigtail everything. I hate when devices are used for continuity of the circuit.

Yes, but even pigtailing could not stop a failure on a receptacle with untightened screws with the load plugged into it. We can try as we might to make things fail safe but as long as human error is involved, this kind of thing will continue to happen.

Admittedly pigtailing does prevent the problem of a "feed though" load that caused the failure in your picture, but it's not a "be all and end all" method.

 

[Volta]

Adding resistance to a resistive load only acts to decrease the total current. There is no reason to expect an OCPD to open for these types of failures. The OCPD just sees current that is below the trip point and does nothing. Even the AFCI will not directly detect this type of heat producing problem. The AFCI only acts to open the circuit after the heat has caused the problem to progress from a poor connection to a ground fault of parallel arcing fault. If neither of these happen (unlikely, but possible) the AFCI will not act to open the circuit.

Wouldn't a combination-type AFCI open from the series arcing?

 

[stickboy1375]

Yes, but even pigtailing could not stop a failure on a receptacle with untightened screws with the load plugged into it. We can try as we might to make things fail safe but as long as human error is involved, this kind of thing will continue to happen.

Admittedly pigtailing does prevent the problem of a "feed though" load that caused the failure in your picture, but it's not a "be all and end all" method.

I agree, luck is luck... if the owner had plugged the space heater into the receptacle I posted, then who really cares how it was made up?

 

[don_resqcapt19]

Wouldn't a combination-type AFCI open from the series arcing?

There is no evidence that a poor or high resistance connection results in series arcing. In fact before the AFCI manufacturers came up with the idea of the combination device, they went to great lengths to say that there is no such thing as a series arc at 120 volts.

 

[mdshunk]

There is no evidence that a poor or high resistance connection results in series arcing. In fact before the AFCI manufacturers came up with the idea of the combination device, they went to great lengths to say that there is no such thing as a series arc at 120 volts.

They guy that comes up with the glowing fault detector will have a real money-maker on his hands.

 

[480sparky]

They guy that comes up with the glowing fault detector will have a real money-maker on his hands.

Gimme some time. I'm still working on my 'plug-in ammeter' that will tell you how many amps is available on the circuit.

 

[Volta]

There is no evidence that a poor or high resistance connection results in series arcing. In fact before the AFCI manufacturers came up with the idea of the combination device, they went to great lengths to say that there is no such thing as a series arc at 120 volts.

Looking at that device, I would think that at some point series arcing occured. Maybe after the destruction was on its way, sure.

 

[acrwc10]

How about using one of these on every outlet.
View attachment 2672
Juat add the desired fuse and no more questions.

 

[ptonsparky]

There is no evidence that a poor or high resistance connection results in series arcing. In fact before the AFCI manufacturers came up with the idea of the combination device, they went to great lengths to say that there is no such thing as a series arc at 120 volts.

Dang and all these years I have been explaining to my customers that the little spark they see when a wall switch operates was an arc as the contacts open under load. Guess arcs and sparks are different. Live and learn.

 

[e57]

What makes you think it failed? I know I can burn a house down with a 5 amp resistive load. Even if the space heater was 10 amps, the resistance at the burnt receptacle could have very well added only a few more amps.

Well - when I hear the words "Space Heater" I instantly think heavily or over-loaded circuit.

This was located in his daughters bed room, and happened over night, nothing plugged into the receptacle but a space heater down stream

Could there have been anything else on the circuit? Some of those things are 1200W, in the past I have seen some old plug-in models at 2000W. Chuck grannies old space heater on with a few lights and other detritus - you could be over the capacity of the circuit. Run that all winter long. Add one weak connection, that gets weaker every winter they supplementary heat the house with a high resistive load through the weakest link of the electrical system - I think the pictures spell it out.

We have been focused on the terminal connections vs. back-stab route here. IMO the appliance itself, and the often weak or worn connections inside the receptical are more likely the way to point blame.

 

[steelersman]

Well - when I hear the words "Space Heater" I instantly think heavily or over-loaded circuit.
Could there have been anything else on the circuit? Some of those things are 1200W, in the past I have seen some old plug-in models at 2000W. Chuck grannies old space heater on with a few lights and other detritus - you could be over the capacity of the circuit. Run that all winter long. Add one weak connection, that gets weaker every winter they supplementary heat the house with a high resistive load through the weakest link of the electrical system - I think the pictures spell it out.

We have been focused on the terminal connections vs. back-stab route here. IMO the appliance itself, and the often weak or worn connections inside the receptical are more likely the way to point blame.

Arcing at the receptacle terminals due to a loose connection seems to be the most likely and sensible explanation IMO.

 

[don_resqcapt19]

They guy that comes up with the glowing fault detector will have a real money-maker on his hands.

I think there was a proposal to require such a device in the 2002 code cycle. I understand there will be one to require a receptacle that has a thermal shut down system for for the 2011 code.

 

[wbalsam1]

I think there was a proposal to require such a device in the 2002 code cycle. I understand there will be one to require a receptacle that has a thermal shut down system for for the 2011 code.

• GFCI 1970's
• AFCI 1999
• TFCI 2011? (Thermal):-?:smile:

 

[wptski]

Gimme some time. I'm still working on my 'plug-in ammeter' that will tell you how many amps is available on the circuit.

The "new" feature in the Ideal Surtest is "ELL" is a estimated load on line. Is that good enough for you?

 

[steelersman]

So today I went to a service call in a house. She had some lights and outlets without power. House was built in late 70's. Romex. Copper. So far so good. Some wires had been added I could tell. Like a 12-2 fished in for a ceiling light spliced through the receptacle so that when the switch was turned on it turned on the light and the outlet as well.

A group of outlets in the dining room and kithcen SA circuit was reading open neutral. I test voltage from hot to neutral and get approx. 50 volts. I figure out which one was the homerunned outlet and take it apart and see a sketchy connection on one of the neutrals. It wasn't stripped back far enough so therefore was making a bad connection. The plastic near the loose connection was burned and slightly melted. I stripped it back properly and re-wrapped it around the screw as it was not a stabbed in connection. These wires were 10-2 to boot, so I pigtailed #12's off of them to connect to the outlet. That solved that problem.

And another problem was a different circuit that lost partial power due to a broken wire from the outlet. Easy fix. But there were a couple other broken wires. I was wondering why these wires were breaking. Oh well. Everything works now.

Anyway I just wanted to share my first experience of finding and repairing a bad connection that was arcing. I explained to the lady that she should consider a service changeout soon with AFCI breakers to protect from more of these possible dangers. Her panel is a FPE stablock. Yikes.

 

[480sparky]

The "new" feature in the Ideal Surtest is "ELL" is a estimated load on line. Is that good enough for you?

No. I want to know how many amps are there.

 

[don_resqcapt19]

Dang and all these years I have been explaining to my customers that the little spark they see when a wall switch operates was an arc as the contacts open under load. Guess arcs and sparks are different. Live and learn.

Tom,
I should have said sustainable series arcing. Yes there is an arc every time you open a circuit and it is a series arc. In the time before combination type AFCIs the manufacturer's made many statements that said a sustainable series arc was not possible at dwelling unit voltages. A "glowing" connection is not an arc....just a high resistance connection that can produce a lot of heat at low currents.

 

[ptonsparky]

Tom,
I should have said sustainable series arcing. Yes there is an arc every time you open a circuit and it is a series arc. In the time before combination type AFCIs the manufacturer's made many statements that said a sustainable series arc was not possible at dwelling unit voltages. A "glowing" connection is not an arc....just a high resistance connection that can produce a lot of heat at low currents.

Just pushing buttons, I knew what you meant.

 

[LarryFine]

And another problem was a different circuit that lost partial power due to a broken wire from the outlet. Easy fix. But there were a couple other broken wires. I was wondering why these wires were breaking.

Perhaps poor stripping habits by the original installer. I've seen plenty of guys ring wire when stripping it. They squeeze the cutters and rotate the handles. Now there's a nick in the wire, and that's where it breaks.

Sooner or later, especially with handling, the wire breaks right where it was stripped.

I tell them that the insulation just rotates with the pliers, and they're doing to the conductor what they want to do to the insulation. I teach to squeeze, release, rotate, squeeze again, then pull. I can just squeeze and pull.