Last week I had a service call out to a home with an inoperable circuit. After some looking and talking heres what I found.

Split level home with a 125amp Square D panel in basement.The problem circuit ran from panel straight up to living room hit 6 plugs and some lighting and then dropped back downstairs to a pullchain.

The owner took the power out of the light ran it into a singlegang box for rec then up to a switch then back to the light. All his work appeard fine and no sign of damage anywhere, I looked very closely.

The breaker to this circuit is now dead,in tripped position will not reset. Each and every plug upstairs and through the switch's main feed on to the next plug have done a melt down, things just melted to each other causing shorts everywhere. The burn did not continue to inside the sleave of the romex but was contained in the box.

This was true of every wire upstairs both the hot and the nuetral. On the downstairs wire there was no sign of damage.

My best guess at this point is the homeowner goofed and wired his plug a dirrect short. He swears he didn't and has done things like this before. He seemed somewhat competant.

This was all on a 15amp square D homeline breaker. Homeowner said when he turned it on he could hear the buzzing for some time but didn't know what it was

Heres the Q's. Why didn't it damage the wire downstairs where he would have made his mistake like it did the upstairs.

When he moved the wire maybe yanked it causing an already to tight staple to cut into the wire? Doubtfull. All wiring has been replaced. No sign of that and it was all looked at closely.

Also should a rep be notified this rings of FP breakers. Or should say UL be notified.

This is obviously a problem of a short and a major overcurrent through the wire compounded by a faulty breaker. Is it just a fluke?

Neil

[This message has been edited by Bomzin (edited 03-28-2004).]

Hey Neil!

Welcome to the forum.

You paint an interesting picture. I'm curious about the through-splices of the branch circuit. In the outlets in the living room, were the receptacles splicing the conductors together, or, were the conductors spliced with wirenuts and a pigtail?

I'm guessing that the "back stabs" on the receptacles were used, or that the terminal screws were consistantly loose, leading to "glowing connections".

Had a heavy load been put on the end of the circuit? . .something like an electric heater or a dehumidifier? The heat degradation over time of the connections behind the living room receptacles, followed by the mis-wiring of the new switch / outlet into a short circuit would result in a higher than normal resistance, strangling the short circuit current. Hence the long buzzing.

Of course, the bad breaker hypothesis is a good one. It's just that SqD, in my experience, has had such extraordinary quality, I would try to rule out any other possiblity.

It sounds to me like poor connections in the fault path, in which case the breaker may have been fine. The path could have provided enough resistance to not "pop" the breaker right away, also resulting in heat and spaterings of metal at each loose connection throughout the circuit.

As to the proper notification procedure: It would be a noble thing for you to report if indeed it was a manufacturer defect. Nothing in it for you, but the manufacturer could learn and/or take corrective action, curbing their liability and, more importantly, increasing future public saftey. All this of course if it was a bad breaker, otherwise a waste of time.

But if you did find out the quickest, easiest way to hande reporting such suspicions, either to UL or manufacturer, let us know. It'd be more likely to report such things myself if I didn't have to do the pre-research.

... I agree with Jps1006, and if possible send the offending breaker back to Square "D"'s R&D dept..Good Luck,..I'm honestly surprised that it failed...I tout Square "D" to my customers as the "Cadillac" of breakers,...well,at least the QO style anyway,...
Russ

After the rewire all lights and everything in the living room where turned on. 4.3 amp load at test.

Rec made the connection throughout the circuit.

This happend right after he did a small rewire downstairs. Although no damage was present downstairs.

All the grounds were twisted with green wire nuts. I also noted the grounding on the water pipe, 2 clamps , did not check outside service.

I have been a service man for going on 9yrs now with electronic experience before that. I always find the cause of the problem. This one has me stumped.

If the Homeowner did short it downstairs why no damage? Last point of damage was upstairs.

I took some pics will post if I can figure out how.

Neil

Also the wire going to the breaker had also done a meltdown along with neutral.

Would a loose connection at the very first point cause this with a short placed at the end of the circuit.


Neil

oops I need to work on my reading comprehension..... sorry Bomzin

[This message has been edited by sparked (edited 03-30-2004).]

At least the breaker failed in the "open circuit" condition. A safe failure. Not like FPE breakers that are known to fail in the "on" position and become stuck on passing large quantities of fault current.....

Sounds to me like the effective ground-fault current path is not so effective. Enough heat was developed to melt the insulation, but not trip the breaker. The 'buzzing' sound means the breaker was at it's very limit. For how long is anyones guess at this point. It does not seem the homeowner will give you much help in figuring this out.

Pierre

At least two things had to happen at once here.

First, a large amount of current had to have been drawn from a point at least after the last damaged receptacle and conductors. This may or may not have been more than OPD was rated for.

Second, the connections to those existing receptacles HAD to have a high resistance. This is evidenced by the burned and overheated insulation only in the vicinity of the connections. (This is exactly the same problem you see with aluminum wiring which is caused by the connections becoming loose.) A normal connection should easily carry a current equal to that of the conductor and the cable would have also faulted if enough current were drawn.

As to the breaker, you say that the wire was also burned on its screw. Question is then, did the breaker fail to open due to an excessive current condition or was there a high current draw within the rating of the breaker which caused the connections to overheat, including the terminal (which was also loose) on the breaker and THAT is what did the breaker in.

Now, a couple of things that bother me about this story. Did the extension wired by the homeowner ever work or was this problem started (and was evidenced by the breaker buzzing) when he completed his work and turned the breaker back on for the first time? If the latter then that would indicate either a problem with something he did or there was something plugged into a receptacle AFTER the last damaged receptacle that drew a lot of current when the breaker was turned back on. I suspect somebody (not you) is being less than forthcoming here.

As I said above, even if the breaker was actually bad (which I doubt), there had to be a reason for the current draw first for anything to happen and we are not hearing about that.

It would be impossible for the breaker to cause this by itself. Once we know exactly what caused the current draw, a determination can be made as to how much it was and only then we can say whether the breaker failed to trip or it was a victim of overheating itself.

-Hal

[quote]Just out of curiousity here, was this a HomeLine series breaker?[\quote]

err ya what did I type.

It's not like this circuit had loose connections all over. I have seen copper burn before and aluminum burn for 40 feet.

Yes, it did go bad immediatly after he worked on it. But still could not nail it down to what he did or why it did not burn downstairs.

This short was between the hot and nuetral not ground.Sitting here looking at some of the receptacles there is no sign of damage to any of the devices. Only to the wiring.

[img] http://www.msnusers.com/Saylor/Documents/electrical%20002.jpg [/img]

I just didn't think u could get as that size of copper that hot that fast. When on a properly sized breaker. It sounds like it was doing the buzz,, short circuiting for some time, how about longer then usual....

maybe the homeowner just did something and is refusing to tell me. He could have tried to fix it himself somewhat befor I arrived and did a cover up.

Neil

[This message has been edited by Bomzin (edited 03-28-2004).]

[deleted]

[This message has been edited by Hutch (edited 03-28-2004).]

i agree with the others that say the homeowner is not telling the whole story. he probably made a stupid mistake and fixed it before you came to save himself embarrassment. feel there is something wrong with the breaker and you wish to contact Sqaure D but you want to tell them EXACTLY what went on when the breaker failed.

say this to the homeowner "this breaker may be defecteve and Square D needs to know exactly what occurred when the breaker failed. If it is defective, thousands of people's lives may be at stake and Square D needs to be able to recall the product."

make sure you don't put the owner at fault i.e. "I know you did something wrong and covered it up" that won't get them to talk.

To me, the key observation is that the burning is at the ends, close to the device terminations.

I made a set for a magazine photoshoot that required a failed and burned connection at a receptacle. All I did was plug in a 1400 Watt electric heater and loosen one terminal screw on the side of the receptacle the heater was plugged into. A pinpoint plasma arc appeared and wandered around, smoke billowed and insulation melted, all the while, the heater made heat and the breaker simply didn't care, 'cause the load was within spec. The process was complete for one terminal in about 10 minutes.

The dozen, or better, burned connections in your client's circuit says, to me, that something was left running for a fair chunk of time.

With respect to the photo, you can email it to: Photos@Electrical-Contractor.net
Bill Addiss will place it in the right thread if you send a note along with the photo naming the thread. Your browser address bar will have one name of the thread, for this one: https://www.electrical-contractor.net/ubb/Forum1/HTML/004062.html

[This message has been edited by ElectricAL (edited 03-29-2004).]

This sounds like only one simple and common thing - loose terminations!

What probably happened is the Homeowner plugged in a Portable Heater on the last Receptacle in the 2nd Floor string - where ever the last Receptacle's Outlet box has Barbequed L-N Conductors.

Using the Receptacle's Terminals to make up the circuitry (back-Stabbed, or screwed to screw terminals), the Conductors were likely put in very sloppily - like being tweeked once they entered the pressure terminals.

Used or extremely cheap Receptacles may have been installed, or conductors were pushed into slots which were previously used and the existing wire was removed very poorly.
If the screw terminals were used, they were likely to have not been tightened properly - either left loose, improper conductor wrapping / landing, or they were simply tightened so much they stripped out.

I have to say this because the resulting damage to the Line Circuit Conductors is an apparent result of extreme heat dissipation - the tell-tale signs of a poor termination at the Device.

If wirenuts were used for makeup at each Outlet Box, then the makeup was poor and incorrectly done.
If you have found fried Wirenuts at each splice, and the burnt insulation travels away from the wirenut, that's the culprite.

At the circuit breaker, the termination was likely left loose or stripped out - if even terminated inside the lug properly.
Have seen some frames where the wire did not get landed inside the termination lug, and instead was wedged underneath it with a sufficient pressure as to allow current to flow.
Loading that circuit upto 5 or more Amperes resulted in the smoke leaving the insulation + the breaker's frame.

To wrap this up, it sounds like a High Load, Long Duration, Multiple loose connections scenario.

The Breaker failed because it was probably reset numerous times under an L-N fault condition - plus it was fried from the poor connection.

Check the effected circuit's white wire termination at the panel, to see if that screw is also stripped / loose, or if the end of the wire is also barbequed.

Most likely, you will never get to the bottom of "What Happened / What Did The Homeowner Do To Cause This" by asking directly - only by asking indirectly will you stumble across the real explaination!

Ask about how long the Heater(s) was/were plugged in before the breaker first tripped, and if the heater ran for a long time too.
Hint around as if you have used many old or used Receptacles before, with the back-stab technique and "How Easy They Work" - this is almost a 100% guarantted confession "bait story"
Throw in something in the lines of stripping terminal screws and still using the device "Because It Works Just Fine", and maybe you will be ready for additional clues to "Pop-Up".

Sorry, but this just sounds too much like high, long duration loads with poor terminations. A fault would have resulted in much different scenarios.

There is one other possibility to think of - maybe a larger breaker was used for the first part of the damage - like maybe a 50 amp breaker to "Keep From Turning Off When All 8 Of The Heaters Were Running", and the 15 Amp breaker in place now is just a Scape Goat for the whole thing!
May have even been directly above or below the 50 Amp breaker and became fried from the extreme heat transfer!

Good luck.

Scott35

Scott,


Are you saying that electricians should intentionally spread dangerous misinformation?

In the words of the OP: "Each and every plug upstairs and through the switch's main feed on to the next plug have done a melt down, things just melted to each other causing shorts everywhere."

It seems this would require a high impedance path and the shorts to occur in sequence, starting at the fault furthest from the breaker. Or a bad breaker.

Furthermore:

"Also the wire going to the breaker had also done a meltdown along with neutral."

and

"Sitting here looking at some of the receptacles there is no sign of damage to any of the devices. Only to the wiring."

This doesn't fit the loose terminal theory very well.

Are you sure that there isn't damage to the cable outside the boxes? Even if there is no damage visible from the outside, there could be damage on the inside.

[This message has been edited by C-H (edited 03-29-2004).]

Sorry scott all a nice theorie and all but not buying it. Been there seen that this is not the case.

As for the cable outside the box's all of it was removed. I cut some of it mid point and no sign of damage.

I've been contiplating all day on this with some of the info given here.

Also went back and talked to the wife. Nothing was plugged in. While he was working on it is when it happend. Towards the end of the project. Homeowner has done own electrical work before successfully over the years. Dealing with a couples in there mid 50's probably high school sweeties from the picts I see.

Wife recalls 2 buzzing sounds one short. The other longer possibly 10-15 seconds.

Theory: HomeOwner,<HO>, causes a direct short downstairs, tries it once and shocks the system doing unknown amount of damage to all those push connections on the back of the plugs. HO fiddles with it checks connections he made and re-energized the circuit, here comes the long buzz.

Current should peak here and breaker should trip, but doesn't.Possible damage to the breaker also. Wire heats just enough to melt the unjacketed wires. The jacket may have drawn the heat away, acting like a heat sink along with the plugs. Looking at the plugs they have almost a 1/4 of copper showing on the back of some of the push connectors. But in the same respect they all appeared tight and no sign of burning was observed going into any of the plugs, it all stopped just that 1/4 short of the plug and about the same on the sheathing end.

His final connection he made using the screw connections on the rec. I'm not totally convinced he hooked the plug wrong maybe , maybe not. But he definately damaged something in the proccess. Alot of electricians around here will damage the wire when stripping romex.Just plainly slice into it with there trusty razor knife and fillet it open.

Lets just say something happend didn't find it while I was there. So no way of telling now .


I guess the question now is. Was that breaker operating right at it's maximum potential, just a combinations of some bad luck and semi loose connections.

How many amps does it take to heat 14guage?

Good 'Ol Murphy at work

Neil

Neil,

I may be the only one, but I can't get past MSN's security. Passport.net lets me sign in, then tells me "access forbidden", HTTP Error 403.

Do you still have the photo to send to Photos@Electrical-Contractor.net?

Al

Will send it to web master.
Neil

Did the breaker trip before the damaged wire caused a fire? If so, it is not "defective".

Not being able to reset a breaker after multiple trips is not an indication of a defect. UL only requires a breaker to be tested for 2 operations (Close - Trip - Close - Trip) at rated fault levels.
Trivia note: Square D Homeline breakers have the same trip mechanism as their QO breaker line.

Why are we assuming the damaged was entirely caused at this moment in time? Maybe all of the devices had been damaged in the past and the addition of the new wiring/load was simply "the straw that broke the camel's back"?

deleted because of redundant post

(read the whole darn thread before responding!!!)

[This message has been edited by CTwireman (edited 03-30-2004).]

from Bomzin

"Here's a picture"




[This message has been edited by electure (edited 03-30-2004).]

This picture shows the insulation burned a short distance away from the backstab. Right next to the receptacle the insulation appears fine. Is that true? Also, what are those nicks in the hot and neutral? Were they always there or are they a result of your removing the wiring?

-Hal

Those look like Leviton #5248 "backwire only" receptacles. The only time I've ever seen those used was in Las Vegas and California. Must be a western thing.....

-Peter

The nick on the nuetral is mostly because of wire seperation when I removed it from the box. The hot wire was found that way having melted back away from the wire. The hot wire did get warmer then the nuetral. Serious signs of heating were found on both wires.

No the wires did not burn right next to the receptacle or even into the jacket of the romex. Only on the exposed portions out of jacket.

I don't think this was breaker failure. It did trip before fire. It did pass the first trip test. I would say failed the second due to unknown reasons. There are alot of variables here.

After talking with the wife abscent the husband I would say when he turned it on for the second time the breaker held way to long right at it's limits.

The husband I do consider somewhat competant, he had managed to put in Arc faults for his bedrooms and had done varios switchs around the house including 3-way's. Like I stated before his work looked fine and no signs of damage in the areas he worked. I did check some of his stuff at his request and all was fine.

I've had a brain fart once or twice in my day and wired up a short. I average probably 3 service calls a day for many years now and have never seen this before, that I recall under these circumstances.

These people have lived in this home since it was new and I can rule out these folks loading up a circuit and throwing it on an oversize breaker.

Maybe this is just something that has been coming to a head due to other unknown circumstances. There are just to many variables and although I did look over everything carefully as we took it out. Because I do like to find the culprit so I can say, SEE HERE IT IS. It's just not to be the case this time.

I am happy to answer any more questions any of u may have on this, I think C-H had it right with an already impending high impedance path, probably made worse the first time it was energized.

Neil

Oh and CTwireman wins the booty prize for naming that receptacle. You know they were budgeting when u see those in a home.

Neil

Thanks Neil & Scott for getting the picture up.

Neil, you certainly found an interesting one.

From the clues you've shared: The situation is truly puzzling.

The conductors inside the cable sheath being unburnt, and the devices being unburnt is a show stopper.

I wonder about the original construction crew. . .who they might have been; what they had to deal with in the way of weather. Are any of the floors finished wood that would have required a floor sander? (Around here, they're wild cards. I've seen'em hook cheesy alligator clips on unfused buses). But all of this would have burnt to the device. . .

It's almost as if, prior to devicing, too much heat was blown or radiated into the roughed in boxes, melting the exposed insulation. The ends that were eventually stripped and connected to the devices were back inside and somewhat protected from the heat. The original installer felt the damage would "get by" and left it.

Following on this idea, you may well have had two problems that you fixed. Beside the tripped breaker, you found and replaced legacy circuit damage left from the original construction crew.

Was not cause by an external heat source. The switch box in the room had aother branch off of it running to a receptacle that was out of the loop. No damage on the power wire to that 1 Rec. But in the switch box the power wires hot and nuetral were melted that were in the loop .. Both under wire nuts

Also I think browning would be observed with that kind of heat on the jacket.

Neil

Alright, here is wild theory:

Let's assume the magnetic trip on the breaker failed. There is a short at a receptacle, which passes a lot of current for a second or two until the thermal element in the breaker trips or simply burns out. That's the "buzzz"

The wiring between the short and the breaker are heated very, very, rapidly by the current. As the insulation begíns to melt, the breaker steps in. In the jacketed part of the cable, the energy is conducted into the jacket and grounding wire thereby removing enough heat to prevent the conductor insulation from melting. Near the terminals, the heat is conducted into the metal of the receptacle which removes enough heat to prevent the melting of the insulation to continue.

The heat in the section of unjacketed wire that is far from the terminal has nowhere to go but through the insulation into the air and free convection and radiation at the outer surface of the insulation. This is much less efficient than conduction in copper or even in PVC.(*) End result is that the insulation melts.

* In fact, to calculate the temperature rise from a short circuit you usually assume that there is no heat transfer to the surroundings.

C-H i don't think u are to far off. Expecially in the area of why certain parts of the wire melted. See my post 1 or 2 up.Or really any of what u posted for that matter. To this , just dawned on me. When the guys wired the house upstairs the wiring coming out of the box was longer then usual. Almost 12''. Downstairs HO had plug on fairly short wires. 3" out of box. The downstairs plug and sheathing would have absorbed the heat being shorter. Also exesive bends or tight bends upstairs compounded with a short may account for some resistance in the circuit.

So. Did this breaker fail?!? Someone posted that it only has to work twice to pass a trip test.

That posses the question. Is this a 1 in a million shot, or 1 in a 100. Do I just hand it off to a Rep, where it may just end up in the garbage or send it to square D themselfs or to UL for that matter.

I feel very confident in my appilities and this looked like a direct short caused by the homeowner. With a breaker not turning off as soon as it should of. This circuit is under 80' long.

I'm just not so sure it was the breakers fault.

Were just about there boys ,. Thanks for all the input. Now what do I do with all this info and my bag of burned parts.BBQ hot gotta go grill

Neil