As you all know, a troll hijacked one of my posts and kept insisting that omitting a neutral on a pure 240v circuit would cause a fire, which would invalidate the insurance. But that brought up the question in my mind, can improper wiring actually cause a fire?
Presumably any fool is capable of using the right gauge cable and breaker for the current, terminating all cables in junction boxes, using a suitable cover on the boxes, and securing the cable so it won't rip out of the box. Given that, could doing anything improper actually result in a fire? Seems to me that errors will result in the circuit not working, or a problem occur in the (presumably) fire resistant boxes. Given those basics being done right; what errors would result in fires?
(I suppose one example might come from my cottage. It has cable entering the back of a kitchen cabinet and then going up to, and across the top. A mouse chewed through the wire to get into the cabinet and short circuited it, inches away from a pile of paper napkins. Seeing what happened to the mouse, I have to think I was lucky it didn't catch the napkins on fire. Obviously the cable shouldn't have been in the cabinet.)
Go to the store. Buy one of the testers you insert into a three pronged plug that has the three lights. It gives you three indicator lights that tell you if the circuit is wired correctly, or if the wires are not correct.
It is absolutely amazing how many circuits are wired wrong. Both in homes and in commercial buildings. Wiring that was done by professionals.
I cannot say from my limited experience with electrical circuits whether or not what you suggest can actually start a fire.
I can say from experience as a safety inspector how absolutely amazing it is that so many circuits are wired incorrectly.
Tell me about it. About 7 years ago, I did a gut renovation on the house I'm living in now. 100-year old wiring out. Complete new 240V 150A electric system from the meter in. Licensed electrical contractor, permits, city inspector, the whole nine yards.
Just one problem -- the electrical contractor apparently didn't have the right tool to properly crimp the neutral connection to the overhead drop from the utility pole. So he faked it with some screw-down clamp connector he had. A couple of days after I moved in, I'm noticing the lights getting dimmer and brighter and various things get turned on and off.
I called Con Ed. They had a guy in a bucket truck at my house within the hour. He diagnosed the problem as a bad neutral, took a look at all the connections, found the problem, re-did the connection with a big mongo crimp tool, and all was well.
Tue, Dec 12, 2006, 4:50am (EST+5) snipped-for-privacy@Yahoo.com (Toller) doth burbleth: As you all know, a troll hijacked one of my posts and kept insisting that omitting a neutral on a pure 240v circuit would cause a fire, which would invalidate the insurance. But that brought up the question in my mind, can improper wiring actually cause a fire?
If a question was asked, how are we supposed to know if it's a troll, or you?
Can improper wiring actually cause a fire? You sure you're not a troll, hijacking this post? Last I knew, yes, improper wiring CAN "actually" cause a fire. Seen it happen. Try using google once in awhile.
Absolutely it can. Don't you ever read your local newspaper? It happens with disturbing frequency.
That's an awfully big presumption, in my opinion, based on some of the stuff I've seen by previous owners of every house I've lived in.
Improper connections with aluminum wiring is the biggie. A fellow I used to carpool with lived across the street from a subdivision that was built in the
70s, with all homes wired with aluminum. One morning when I came to pick him up, I saw that one of the homes had clearly just had a massive fire; he told me it was common in that subdivision -- that about one house a year burned, all due to faulty wiring.
Inadequate overcurrent protection is another. Just last week, at Lowe's, I had to explain to another customer why it was not a good idea to replace a 15A breaker with a 20A. "But it keeps tripping...."
Backstabbed connections on receptacles and switches, that work loose over time and spark.
Receptacles recessed too far into a combustible wall (e.g. wood paneling). Not dangerous in and of itself, but when combined with one of the problems cited above, it's a disaster waiting to happen.
Much more information here:
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this excerpt:
There are two basic types of arcing faults ? series and parallel. Series arcing faults occur when the current-carrying path in series with the load is unintentionally broken. Arcing may occur across the broken gap and create localized heating. The magnitude of the current in a series arc is limited by the load. The series arcing currents are typically well below the typical circuit breaker?s ampacity rating (often referred to as handle rating) and, therefore, would never trip the conventional circuit breaker either thermally or magnetically. Series arcing can lead to overheating that can be hazardous. Examples of conditions that may result in series arcing faults include loose connections to a receptacle or a wire splice, a worn conductor from over flexing of a cable, or a pinched cable in which the conductor has been severed.
A parallel arcing fault occurs when there is an unintentional conducting path between conductors of opposite polarity. Parallel arcing is only limited by the available fault current of the source and the impedance of the fault. If the fault is of low impedance, then the overcurrent device should open. However, when the fault impedance is relatively high, there may be insufficient energy to open the overcurrent device. This can cause arcing that can propel particles of molten metal onto nearby combustibles. A short circuit caused by an intermittent contact is one type of parallel arcing fault that can create hazardous arcs. A line-to-ground arcing fault is another form of parallel arcing fault and occurs when an ungrounded line conductor is faulted to a metal enclosure or other metal structure in contact with a grounding conductor. Examples of these are cords cut by furniture with a metal leg or loose wires that contact a grounded surface.
Parallel arcing faults are known to develop in three stages: leakage, tracking, and arcing. Leakage currents normally occur in every electrical wiring system due to parasitic capacitance and resistance of the cable insulation. Leakage current values below 0.5 mA are considered safe. If the wiring is maintained in good condition, the wiring may be used safely for several decades. However, when the wiring is subjected to moisture, conductive dusts, salts, sunlight, excessive heat, or high-voltage lightning strikes, the insulation can break down and conduct higher leakage currents. As leakage current increases ? undetected across the conduction path ? the surface can heat up and pyrolyze the insulation. This process, known as tracking, produces carbon that generates more heat and progressively more carbon. Although this process may continue for weeks, months, or longer without incident, eventually, sustained arcing may occur.
Parallel arcing faults are generally considered more hazardous than series arcing faults, since there is more energy associated with a parallel arcing fault than a series arcing fault. Parallel arcing faults usually result in peak currents above the handle rating of the conventional circuit breaker. This may trip the circuit breaker magnetically, if the impedance of the fault is low and the available fault current is sufficient. However, in many instances, the available short-circuit (fault) current is not sufficient to trip the circuit breaker instantaneously (magnetic trip). In addition, in many instances, the fault may be intermittent, so the overcurrent will not be sustained long enough to trip the conventional circuit breaker thermally.
Sure it can- but there's "improper" as in *not-quite-up-to-code," but still done in a relatively sane manner, and then there's "improper" as in the case of a guy who hooks a shop full of tools up to a light-duty extension cord and plugs them all into one outlet- maybe with a quarter stuck in the box in place of a fuse. Or the guy who wraps stripped wires around a light bulb, and sticks the other end of the bare wires directly into the recepticle because a plug and a light socket are too much bother.
It's the latter that makes the electrical code such a good idea in the big picture. While it's tough to imagine someone actually doing things like that, I've seen it plenty of times when doing remodeling work in the past.
Given the basics being done right, very few. Once you've got the basics done properly, and I stress properly, you're then worrying about what the code has to say about the worst case senario- like having wire in conduit or MC for commerical structures. It's not that the absence of a metal coating will cause a fire- it's that there's a chance that some yahoo will drive forklift tines into the wall and rip the insulation off the wires causing them to short. That's the part that will cause the fire, not the intact wiring. I've got a couple of things that are not strictly to code in my shop, like using a plastic box outside of a wall cavity in one or two places, but there's a common sense rule of thumb going there- namely, that if anything were to whack one of those boxes and break it, it will have been me that did the whacking, and I'll be right there to shut off the breaker and grab the fire extinguisher if need be. If someone else were using my shop, I'd make a point of replacing those.
That's a case where code will at least help you avoid a problem. Within sane limits, you should always try to keep things up to code- there's a good reason why those rules are in place. If you deviate from them, you may never have a problem- but then again, you might. Not worth the risk, IMO- especially when they sell books with the information a guy needs to do the job right for less than a single electrian's visit.
One time, a crewmember of mine plugged a 220v "distro panel" into what was supposed to be a standard 220v / 50A / 1PH range plug. The plug was wired (3) phase, so as each amp in a rack of (4) that was plugged in was switched on, the smoke was let out. The cost to repair all four Crown amps was well over $1200 US (1992). Breakers never tripped, but there was no fire. Before the amps were switched on, several people got nailed by hot grounds while wiring the stage. None of the "nailees" mentioned it to the others. Fortunately, nobody tried to turn anything else on, especially the FOH racks or consoles.
I'd be more worried about electrocution than fire, but I'd still worry about fire. If the amps were coated with woodshop dust, I'll bet there would have been a fire.
Here's one for you in that same vein: A couple of years ago, in a brand new house I'd just finished, the same things suddenly started happening.
No 220v in the house where the circuits had worked before, timers/clocks in appliances were going wacko and turning off and on, lights were dimming/brightening ... gave me cold chill thinking that here was a _serious_ electrical problem in a house that we had just that very day accepted an offer on.
Since it was after 6 in the evening when I noticed the problem, and scratching my worried head, I shut off the Main power, tried to call the electrical contractor to no avail, and had no choice but to wait until morning to take any further action.
Around 10PM that evening I decided to go for a walk, and on the spur of the moment decided to walk back by that house. On the way I noticed an HL&P company truck working late on a pole about a block away from the new house.
Hmmmm ... walked over out of curiosity and, long story short, the electric company had put in a new transformer earlier that day after it's pole had been hit by a construction truck, and wired it wrong!
Apparently the neighbors had been calling electricians all evening and everyone was scratching their heads as to why there was a back feed on their neutrals.
Damn thing is that, if I hadn't decided to go for a walk that evening, I would have called the electrical contractor the next morning, jumped all over his ass, he would come out and have found NOTHING wrong, we would have never known what, why, or how, and I would probably still be waking up at
3AM in the morning, in a cold sweat, worrying about the electrical wiring in that house with kids living in it!
The aluminum wire and the inadequate overcurrent protection fall outside my conditions, but not the backstab receptacles. They can give the series arc your article speaks of. (my mouse gave the parallel arc...) Would a proper junction box, properly covered, contain the arcs? Your article does not address that issue, but it seems important. Arc are obviously bad, but if the box contains them...
"insisting that omitting a neutral on a pure 240v circuit would cause a fire"
A, now we understand why you are so incensed. You miss read my posts. I did not say that as you allege, above.
As regards liability, I simply said that you could be held liable for a fire caused by improper wiring and that your insurer might well be off the hook if it was shown that you did so in violation of the codes or law in the area.
The 10/2 vs. 10/3 argument made was that it would be prudent to install the later regardless the immediate plans for the use of the new 20VAC run.
You concatenated several posts into an argument not intended. My apologies for getting you off track.
I have one of those testers and found the circuit to my microwave had the hot an neutral reversed as I was trying to remove a broken bulb. I did NOZT unplug the thing and caused a short across the bulb socket and ground (I assume).
Instead of tripping the breaker downstairs, it fried the component board in the Microwave. I suspect that, had the outlet been properly wired, the short I caused would have tripped the breaker an I would have a working Microwave after resetting it.
No way, now, to prove this suspicion, but I should have 1. unplugged the damn thing and 2. rewired the outlet too.
I did re-wire the outlet before the warranty repair guy got there and I didn't share the entire story with them when I called or when he was there. So I can't report that the improperly wired outlet voided my warranty repair (a new motherboard) and cost me a $300 Microwave. But I have my suspicions.
One hopes it would, but for how long? They use electric arcs to weld steel, you know... One of the saddest, and at the same time most infuriating, things I've ever read was an article in the Anderson (Indiana) Herald some ten years ago, back when we lived in the area, about an Anderson family that had died in a house fire. Mom, Dad, three or four kids. One survived. Said there had been problems with the electrical outlets sparking, feeling hot to the touch, and smelling of smoke -- but they slept in the house anyway. No smoke detectors, either, by the way.
If the outlet had been properly wired, the shell of the socket would have been connected to the neutral conductor, instead of the hot. Bridging the neutral to ground would not have tripped the breaker, since the two are at the same potential anyway.
My sincere apologies to you and tofler. In my area, my 220 circuits (to stove, ac, Water healer all contain a neutral and a bare ground wire.
It seemed that this was done in accordance with the electrical codes in my area as the work was inspected by the City when the house was built.
Maybe "code" allows it in my area.
It seems to me that running a length of conductors to one's shop to operate a 220VAC device is an expense of time, energy and money that would warrant the (initially) redundant neutral given the minimal additional cost of the fourth conductor.
My experience retrofitting homes and garages to serve new uses convinced me that one never knows how something may be used down the road.
Oh, screw it. The OP is long out of the conversation and you guys are not so much interested in his issue as you are in winning.
The stove needs it, because the control and lighting circuits are 120V, and the 120V loads require a neutral.
The air conditioner probably does not, and the water heater almost certainly does not, need or use a neutral.
And what exactly do you mean by "contain a neutral and a bare ground wire"? I wouldn't be surprised if your water heater, for example, is wired with 10/2 with ground -- black, white, and bare. The white is *not* a neutral in that case. It's supposed to be permanently re-identified to show that it's a hot conductor, but many electricians never bother, and many inspectors don't notice, or don't care.
It's never a Code violation to add unnecessary wires that aren't connected to anything.
The NEC doesn't *prohibit* it anywhere. The dispute Toller and I have with you is over your insistence that Code *requires* it -- which is complete nonsense.
It's a *waste* of money. 240V devices do not need -- in fact, do not even
*use* -- a neutral conductor.
If Toller installs a 3-wire 240V outlet (two hots and a ground), there is absolutely no concern that "down the road" somebody else is going to try to plug a load that requires a neutral into that receptacle -- the plug won't fit.
I'm interested in seeing *accurate* information posted about electrical wiring.
In other words -- you actually read the Code for the first time...
Go right ahead. Nobody is stopping you -- it's your money you're wasting by adding wires that are not used.
And as long as you're done insisting that the Code "requires" things that anyone who has actually read it knows that it manifestly does not, then I'm done telling you you're full of beans. Fair enough?
"Toller" wrote in news:myqfh.7388$ snipped-for-privacy@news02.roc.ny:
What he said was absolutely 100% wrong. The neutral in a pure 220vac does nothing but serve as a safety ground in the rare event that something were to go wrong and will help keep one from being shocked.
Sure.....anything can happen even in properly wired situations.
Fires that started from electricty are generally due to a few factors. A poorly made connection will causes things to heat up and get hot and could eventually cause a fire. An piece of wire carrying too much current will do the same thing.
That situation is one that could happen at any time. Romex is common in walls, ceilings and attics...eveywhere a mouse is likely to be found.
There are no 100% safe electric wiring, devices, etc. There are circumstances that can arise that will cause fire, death, injury, etc.
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