Burnt Outlet

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Had a potential fire hazard occur a few days ago when a plug for an electri c baseboard heater (the outlet is behind some furniture) apparently develop ed a bad connection. Perhaps the plug was not seated properly or was dislod ged by a tug on the cord? Anyway at some point things got hot. Two smoke al arms failed to go off and in the morning I was told by a family member that "the heater isn't working and apparently has fried itself."
There was a heavy smell that something had fried. Upon inspection the outle t and heater plug was fried and there was a burnt spot on the back of the f urniture. The white wire insulation inside the outlet was totally crunchy, so there was considerable heat at the connection and the heat conducted up the white wire.
I guess an AFCI breaker might have shut this down, and I see one company se lls temperature sensing outlets. I wish the outlets were more commonly avai lable. The breakers would never fit my old box.
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On 2/16/2014 1:27 PM, Davej wrote:

You were well past a "potential" hazard at that point.
More likely there was a loose connection on the outlet...isn't the "backstabbed" type by any chance't?
That sounds like a very risky installation/usage pattern, anyway, of placing an electric heater behind furniture...
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Yes indeed. Congratulations Davej. You dodged a bullet

I think only the plug and cord were behind the sofa.
When I had this problem, it wasn't behind furniture, but I was sleeping.
I also had a very old receptacle. Mine was covered by 20 layers of paint, but in the case of Davej, if it was more than 10 years old, maybe he should have replaced the receptacle before using it for this, certainly if it was at all loose or more than 15. I presume you've replaced it now. Make sure it grips it firmly and after the heater has been running for 20 minutes, hold the plug in your hand to see if it is warm. It shouldn't be at all warm.
I've also seen clamps to hold a plug into a recept. Held on by the screw in the center. Or you can make one
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On 2/16/2014 2:46 PM, dpb wrote:

not clear.
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Christopher A. Young
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On Sunday, February 16, 2014 3:58:50 PM UTC-6, Stormin Mormon wrote:

The outlet was old, perhaps 20+ years, but not coated with paint. The outle t is behind furniture but the heater isn't. The cord is not in a place wher e it would normally be touched or tugged. I remember unplugging the heater last Spring but I believe a family member plugged it back in this Fall, and that I suspect may have been the problem. Perhaps they did not plug it in carefully and fully? I never use the "backstab" holes in outlets because I don't feel they provide a reliable connection. I think I will be installing a dedicated outlet for this heater in the near future. Thanks for the comm ents.
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On 2/16/2014 11:16 PM, Davej wrote:

but the heater isn't. The cord is not in a place where it would normally be touched or tugged. I remember unplugging the heater last Spring but I believe a family member plugged it back in this Fall, and that I suspect may have been the problem. Perhaps they did not plug it in carefully and fully? I never use the "backstab" holes in outlets because I don't feel they provide a reliable connection. I think I will be installing a dedicated outlet for this heater in the near future. Thanks for the comments.

I'm pleased the outlet did not catch fire, and you and your family are safe. Might be a good socket to install a two dollar socket, not the bargain basket 59 center. Cheaper than rebuilding.
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wrote:

They are starting to sell AFCI receptacles and the code is evolving to allow you to simply replace the first one in a string to protect that receptacle and all down stream from there. It is a compromise since the first small leg of the circuit is not protected but it is a compromise in the right direction for people who are not going to do any extensive rewiring.
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On 2/16/2014 1:27 PM, Davej wrote:

The smell produced by overheating was probably not smoke. Not exactly reassuring, but if there had been an actual fire the smoke alarms should have gone off.

There can be a loose connection that produces a "glowing connection" that is stable, and an AFCI won't trip on arc detection because there is no arc.
In 2001 UL did testing for Cutler-Hammer on glowing connections. Steel connection screws (plated)were the easiest to create a glowing connection. A few amps could produce a glowing connection. The heat can, obviously, start fires. And the heat can carbonize the plastic, which can create a leakage path to a ground terminal or the yoke. Since AFCIs also have a ground fault detector (at 30 mA), that can cause an AFCI trip. Of 16 receptacle trials, 9 tripped the AFCI. (In 6 the wire burned open, and in 1 the test was ended after 35 hours.) A glowing connection might also eventually become an arc.
The earliest AFCIs would only detect high current arcs - between wires. They would not detect a loose connection, which is lower current than the circuit breaker rating. More sensitive AFCIs were required in the 2002 NEC, and they can detect a series arc (?above 5 amps). The older ones will still trip on a ground fault.

As gfretwell wrote, AFCI receptacles are now available. In addition to installing them as in his post, you could put AFCI receptacles next to the panel and use the wire-through feature to protect existing circuits.
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<stuff snipped>

I wired in three new 20A circuits to service two space heaters and a convection combo oven. Since I knew where the first outlets were on the branch circuits I simply replaced those outlets with Leviton AFTR2-W SmartlockPro Outlet Branch Circuit Arc-Fault Circuit Interrupter Receptacle, 20-Amp units ($25 each at Amazon) and connected the downstream outlets through the load connections.
The only real downside of doing that is that when an AFCI outlet trips, you have to roam around the house looking for it. I've made an addendum to the ever-growing list of notations inside the panel door of where they are (along with GFCI's wired the same way) but it still complicates things.
There are circuits I'd like to protect where I don't necessarily know where the first outlet in the chain happens to be (is there a way to determine that?) so they would have to be protected by AFCI breakers instead of AFCI outlets.
The circuit breaker AFCI's are almost twice as expensive and require a neutral pigtail connection in the circuit breaker panel. Since my neutral bar is already at capacity, the outlets seemed to make more sense cost-wise and installation-wise.
I have a question for you. Is it "code" to use two neutral buss bars in a circuit breaker panel? The one I just bought is rated for putting two 12 gauge wires under one screw but I don't like to do that if I can avoid it. I could remove the old one and replace it with the one rated for two wires per terminal and double up all the neutrals but I would rather install a second one on the opposite side of the panel and still connect one wire per terminal. Just not sure that two separate neutral buss bars is permissible.
I have to admit since reading about what you wrote about the UL tests I am not sure arc fault protection devices are worth all the effort. I've had two meltdowns already from plugs that were either not fully plugged in or had come loose and one because an six-outlet adapter's crimped internal buss bar worked itself loose. It would be nice to know if the AFCI could have detected any of those events. I am beginning to think they might not have.
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On 2/18/2014 1:57 PM, Robert Green wrote:

New in the 2011 NEC - if you extend an existing circuit in an area where AFCI protection is required the extension (including wiring) must be AFCI protected. Wiring through an AFCI receptacle (as you did) is one way to provide that protection. Almost every receptacle in a dwelling must now be AFCI or GFCI protected (when originally wired or replaced). In the 2014 NEC some must be both.
Also new in 2011 - replacement receptacles in areas where AFCI protection is now required have to be AFCI protected (several methods) - replacement receptacles in areas that now require tamper-resistant receptacles must be tamper-resistant (that is most of the general purpose receptacles in a dwelling)(keeps kids from putting paper-clips in the receptacle) - replacement receptacles in areas that now require weather-resistant receptacles must be weather-resistant (damp locations, like outdoors)
And replacement receptacles where GFCI protection is now required must be GFCI protected
AFCI or GFCI receptacles may have to be tamper-resistant or weather-resistant.

Or install AFCI receptacles at the panel as in my last post.

You can double-up wires only when the manufacturer says it is allowed. Look at the label for the panel. Neutrals are never allowed to be doubled-up - it is a code violation (408.41).
It is relatively easy to add ground bars. The label for the panel should say what accessory bars can be used. If you have ground wires on the existing neutral bar they can be moved to the ground bar (and maybe doubled-up). Neutrals can not be landed on a ground bar (the enclosure can not be used as the neutral-path connection from ground bar to neutral bar in a service panel).
I don't know if accessory neutral bars are available. They are not as easy to install. Other than in a service panel, they have to be insulated from the enclosure, and you have to figure out the size of the conductor to connect it to the existing neutral bar.

Was it a high resistance or arc? Some loose connections are an arc. In the research done for Cutler-Hammer about 1/2 of the high resistance connections resulted in a ground fault trip when leakage to ground resulted from the heat. The 30 mA ground fault trip in an AFCI is there for that reason. And a "glowing connection" may turn into an arc.
The NEC keeps increasing the locations where AFCI protection is required. Would be nice if there was data that showed they have a major effect. But they will likely be most useful as the wiring ages.
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<good stuff about new 2011 requirements snipped to be moved to a new thread later>

There's really not room for that in my panel area. I suppose I could eventually figure out where the first outlet in a branch circuit is with a fox and hound. I could ID all the outlets in circuit that way (or by breaker switching) and then disconnecting the outlet that's the most likely candidate and testing for power at the downstream outlets but that's a lot of work and a lot of torquing around of old, cloth covered wiring that is old and doesn't like to be bothered much anymore. Just like me. (-:
<stuff snipped>

Which clearly makes what I have ground bars.

I was under the impression, probably wrong, that if you connected a secondary buss bar with a large gauge wire (#8) to the neutral buss bar that it was acceptable to land neutral wires on the secondary buss bar but now I am not sure where I read that or if it's true. I realize now that the OEM neutral bar on my Square D panel sits above all the breakers and looks to be isolated from the enclosure.
I just looked and it seems that the small buss bar I have can be piggy-backed to the existing neutral bar, but I am going to have to look up the manual for the panel to be sure. Now a number of things have become clearer to me, which is probably good safety wise but is going to mean a lot of work and/or expense to bring it up to code.
Electrically the panel is connected to the neutral conductor just because ground wires are connected to the neutral bus, correct? I think you're saying that the issue is that a secondary neutral buss can't depend on that connection. The Square D panel has mounts for ground buss bars on both sides of the panel. Even moving all the ground wires from the original neutral buss to a auxiliary ground bar won't help because there aren't many grounds (this is a two-pin outlet house, at least on all the older circuits).
I installed a number of dual skinnies just to be able to take high current outlet loads off the old circuits which now primarily serve low wattage CFL lights. I also installed one AFCI breaker with a pigtail before moving on to the cheaper AFCI outlets, in part because of the lack of neutral buss bar connections.

I am not sure what you mean by "other than in a service panel, they have to be insulated from the enclosure." I thought I did this correctly because I recall going out and having to buy one foot of 8 gauge wire to connect the secondary bar going alongside the rows of breakers inside the circuit breaker panel. I'll have to review my notes about that. I did notice Square D make two identical forms of the buss bar except one was tinted green, the other was all silver which made me also believe that they could be used to ":land neutrals" (I like that phrase) as well as grounds.

One was an arc because you could hear it. The others were most likely high resistance.

Someone mentioned thermally protected outlets that cut out when they get too hot. I've never heard of them. Are they something standard in the industry? Would they offer protection against high resistance connections that the AFCI's don't seem to provide?

I suppose that the data will fill in over time. Based on the number of breaker trips I've experienced in my life, I suspect that breakers have saved my life a lot more often than most other protection devices including my firearms. (-:
Thanks for your input, Bud.
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Bobby G.



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On 2/20/2014 8:23 PM, Robert Green wrote:

Making a map with device locations and circuit number is real useful, but a PITA. Would give you an idea where the first device is.
If you AFCI the first receptacle and wire through the rest, the device protects the wiring downstream. All the load is at or downstream. The AFCI receptacle will protect the wiring back to the panel from series arcs (loose connections) by disconnecting the load that maintains the arc.

I assume that if there is a wire-connection that would work. You have to figure out what size wire is appropriate. Slight chance an inspector might object to using something the manufacturer calls a "ground bar" as a neutral bar.

A subpanel near the service panel is another possibility. (But then you will never be able to sell your house - according to one opinion. And you won't be able to get insurance. And a house inspector may say the house should be torn down. And it should be torn down. And that does not include the shame of having a subpanel.)

In a service panel the neutral and enclosure are connected together. Could be a wire. Often is a screw and looks like a mounting screw but may be green. If the neutral and enclosure are bonded, an added neutral bar would not have to be insulated from the enclosure (but may not rely on the enclosure as the electrical connection back to original neutral bar).
In a subpanel, an added neutral bar must be insulated.

I have never heard of thermally protected outlets. Is that feature UL listed?
And AFCIs may trip on a ground fault caused by a "glowing connection", or if a glowing connection turns into an arc.

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<stuff snipped>

After thinking about the for a while, I realized I could use my X-10 signal strength meters to discover the first outlet on a branch circuit. If I place a test transmitter on another branch, the X-10 meter will show noticeable signal attentuation as measurements are taken at each outlet on the branch circuit in question. I often use that technique to "zero in" on noise generators. As you move closer to the noisemaker the noise reading function of my XTBM meter shows an increase in the noise signal level (in millivolts). Never thought the technique could ID the first outlet in a circuit, but I think it will.
<stuff snipped>

I had the panel inspected after I installed the first set of dual skinnies. But I think at that time I had moved all the ground wires from the panel's legit neutral bar to the ground bar. I was mostly concerned at the time that the inspector would disallow the dual skinnies because of the potential to overload the panel. It was obvious from what I had done, though, that I was relieving the older cloth-wire circuits of heavy loads (like toasters) and using the new 12/2 romex instead. The overall load on the panel wasn't changing, just the distribution of that load. Which brings up another subject. Today with my tong meter I realized that one side of the panel was pulling way more amps than the other. I guess that's for another thread, too. What happens when a circuit panel is unbalanced and has substantially more of a load on one leg than the other?
Since the last inspection I have added more circuits but the overall load is still way less than the total the panel is rated for. Unfortunately now the neutrals are connected to the auxiliary buss bar and not just the ground wires and I recall that was new work, post inspection.

No subpanels for me! A long time ago I decided that this house would probably have to be "gutted" when sold so it's not a big issue. Part of the problem is that it was built in 1941 when there was a shortage of everything and those shortages were reflected in the materials used in the house. No building paper between the floors, badly cured wood on the roof, etc. Fortunately where I live the land's what's worth the most $ and houses like mine are often knocked down so that larger homes can be built to replace them.
<stuff snipped>

Gotcha. I may be safe after all. The question now is whether to double up all the ground wires on the buss bar I installed (with the number 8 wire connected to the panel's original neutral bar) or to install another ground bar on the left side of the panel. I am leaning toward the latter because I don't like the idea of disturbing the old wires yet again and because there's a lot more free space on the left side.

Another reason not to endure the shame of a subpanel.
<stuff snipped>

Dunno. I'll first have to look up where someone mentioned them here and then go on to Google to find out more. They have to be pretty simple to build - just needs a klixon internally to interrupt the circuit in case of an overheat. Look for that in a separate thread as the initial search turned up a number of likely candidates. There's probably a third thread to evolve from this. Is UL listing necessary for approval of the installation of auxiliary equipment like an X-10 coupler/repeater? Now I remember why I haven't invited the inspector back . . .

A temperature "aware" outlet seems to be the solution to glowing connections. More in a new thread.
Thanks for your input, Bud.
--
Bobby G.




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On Wednesday, February 26, 2014 5:59:43 AM UTC-5, Robert Green wrote:

How much is way much more?
I guess that's for another thread,

Nothing unless the neutral service conductor was undersized when it was installed and you put such an unbalanced load on it that it exceeded it's rating, eg managing to put close to the full service current rating on just one leg, which is highly unlikely with typical 120V loads.

I don't know what's shameful about using a subpanel. They are installed frequently and properly done, nothing wrong with them. It sure beats tearing out a perfectly good main panel just to add two more circuits. And having the neutral not grounded in the subpanel is trivial, they are made to do that. On the other hand, if you have an old main panel and there are other reasons to upgrade the whole thing, then I can see going to a new larger panel.

I think it's required to be listed and while it's typically listed by UL it doesn't have to specifically be UL, just a recognized testing lab. Given the crap that most X-10 products are, and since you're worried about getting thermally protected outlets, AFCI's etc, I'd think you'd want the X10 repeater listed. Is this an active one or just a passive one? The passive ones, at least some, are just caps AFAIK.
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From 11 to 15A

OK. I remember a long, long time ago I had problems with a Sony monitor at work that an electrician attributed to an unbalanced panel, but balancing the loads didn't solve the wavering on the monitor so while rebalancing at that site didn't help, it probably didn't hurt, either.

I was just "playing along" with Bud who I assumed was recapping odd comments he's seen people make about subpanels. If I misunderstood you, Bud, I apologize in advance.

A total rewire is probably what's required here but as I said, when we leave this house, it will probably be gutted and renovated into a much larger house with all new wiring. Putting in a new service panel at this late date wouldn't be cost effective. I would probably have been forced to upgrade a long time ago except that the advent of CFLs and LEDs really reduced the overall load. Same with a new fridge and AC. Much lower total current draw than the old equipment.
<stuff snipped>

Different concerns. I'd already melted more than one outlet with a space heater whose plug had worked slightly loose. That's a serious fire hazard. With the XTB-II repeater, I am not worried that it will start a fire.

This is an active one designed by a guy who built custom electronics for NASA for several decades. He looked into UL listing but it would have made the device impracticably expensive. He's provided detailed circuit diagrams and component lists and enough information to make me comfortable using the device. We had extensive conversations about worst-case scenarios and while I'd like it to be UL listed, I don't see it as being a dealbreaker, especially considering how useful the device has been. You can see for yourself that this is not typical Chinese made X-10 consumer stuff:
http://jvde.us/xtb/XTB-II_description.htm
Jeff's design and soldering work is impeccable and the XTB-II pretty much eliminates all of the typical problems X-10 faces in the world of modern switching-power supplies. Unlike other repeaters, this unit boosts the X-10 signal to over 25 volts which is usually enough to power through any interference.
Investing in the XTB-II saved me from having to switch to another home automation protocol and protected my substantial investment in X-10 gear. I am sure you would change your opinion about X-10 if you saw one of these units in action and the difference it makes to an "iffy" X-10 setup. The 5 to 10 volt signal strength of standard X-10 gear is just not enough to reach across phases or fight signal attenuation. That's partly because modern electronics are pretty noisy and are often designed to choke RFI which, ironically, is what the X-10 signal looks like to many devices. A 120Khz noise spike at the zero crossing.
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On 2/26/2014 1:23 PM, Robert Green wrote:

Doesn't sound like much unless it is a 60A panel. It will vary depending on what is on anyway

There is a certain party here who has that opinion of subpanels, telling RBM he did schlocky work because he has a subpanel in his house. The same person has strong opinions about k&t, insurance, and some other subjects.
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Thanks. Just wasn't sure what the parameters/problems of unbalanced loads were. Thanks to you and T4 for clearing that up.

As I thought. Thanks for being circumspect about it and not mentioning names. Things have been remarkably civil here in AHR of late. Of course, my blocked senders list is growing like kudzu . . .
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On Wednesday, February 26, 2014 2:23:18 PM UTC-5, Robert Green wrote:

Perfectly normal.

I hear you, but I don't think it would change my overall opinion of X-10. I'm sure it helps increase the reliability and can make it work where it otherwise would not. Part of the problem is that they are not upfront about this problem. I'm sure a lot of people wind up not being able to get it to work because it really should have a bridge/repeater across the phases. Then if you want such a device, they are expensive and as you've found out, have problems of their own, ie not UL listed and there is no guarantee that they will make it all work either. Or maybe you get it to work for what you're currently doing, then want to add something else and that won't work.
The other big problem is that AFAIK, no one is doing anything new with X-10. What you have now, you've pretty much had the same stuff for more than a decade, ie no new products, no improvements, etc. The outdoor sensors don't last, that's another problem. I'd still use it for a simple application, where I put $20 in it and if it works it works, but I would not choose it as a means to more extensive home automation.
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On 2/26/2014 4:59 AM, Robert Green wrote:

Panels will have a rating something like 10/16. There are 10 full size breaker positions and you can put 16 "poles" in it. A tandem breaker is 2 poles, so you could install up to 6 tandem breakers. The label should tell you the rating.
The panel is tested with the maximum number of poles - 16 above - and UL does not allow installing more poles than that. That is done by only allowing tandem breakers in certain positions (6 in the example above). The label will indicate which positions tandem breakers can be installed in. In a 10/20 panel it is all positions. It may also be no positions. A SquareD tandem breaker has a bar on the bottom that has to fit into a slot through the gutter rail, which exists only in the positions where tandem breakers are allowed. These are class CTL panels and breakers (circuit limiting) and they have been around a long time.
The inspector wants to know that tandem breakers were installed in positions where they are allowed.
There are also non-class CTL tandem breakers that can be installed in any position - for older panels that are before CTL came out. I know no one here would ever install one of them in a class CTL panel.
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Panel is a QO CAT QO BW - 20M - 100 - 5
I believe that the 20 refers to the max # of breakers and the 100 is the max current. Otherwise the catalog number don't seem to agree with the listing in the PDF. No idea what BW means. It's hard to read the label because it's a) faded, b) upside down and c) obscured by neutral and ground wires.

This has to be a pre 1985 panel and I haven't found it yet although I found a few like it in this PDF:
www.farnell.com/datasheets/1626663.pdf

From what I can see, that's not an issue with my panel. As I recall, the hot bar (not sure of the technical name of the alternating metal "fingers" running down the center) was the same from the top to the bottom - no specialized slots for tandems (why would there be?). The replacement breakers have a very different connection mechanism that the original ones. The ones that came with the panel have two pronged clips that make the connection to the rail but the replacements have a single claw-like "grabber" - so different looking that I was sure I bought the wrong breakers.

I am pretty sure that at least on of the labels on the panel has the letters CTL but if it came out after 1985, then I definitely don't have a CTL panel. From what I can see of the PDF listed above, the breaker panels that support special slots for tandems look quite different from the box I have which is a series of alternating metal fingers running down the heavy black plastic "spine" of the panel.
http://en.wikipedia.org/wiki/Circuit_total_limitation
Talks about CTL being in place since 1969 and replacement breakers being non-CTL. Even if the panel ends up "dangerously overloaded" isn't the main breaker supposed to trip before anything bad happens?
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