Can improper wiring actually cause a fire?

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The purpose of the ground wire is to ensure that the metal chassis of any device so equipped is always at the same potential as earth ground. If it were not, any fault that might occur inside the equipment could cause the chassis to become live; any human being touching that chassis could then provide an alternate path to ground for the fault current. Current flows in the ground wire *only* in the event of a fault. Under normal operation, it carries no current.
The purpose of the neutral wire is to conduct current from whatever device is using it, back to the service entrance panel and thence to the utility. Under normal operation, there *is* current flowing in the neutral wire (except, as noted previously, in the case of 240V circuits which don't have one).
The two are bonded together in the service entrance panel (note *not*not*not* "the CB [circuit breaker] box" -- any subpanel is a "circuit breaker box", and the two *must* be separate in a subpanel) to ensure that the neutral wire remains at the same potential as true earth ground.
Also, FWIW, the neutral bus bar in a typical panel is in fact insulated from the panel chassis, but also equipped with a bonding jumper of some sort that bypasses the insulation and connects the bar to the chassis. If the panel is used as service entrance equipment, the jumper remains in place. To use it as a subpanel, the jumper is removed.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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snipped-for-privacy@milmac.com (Doug Miller) wrote in

Not on my service entrance box aka CB box. The are both bolted to the frame of the box and are uninsulated.
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You have a panel that's made to be used *only* as service equipment. In my experience, it's more common to see panels that can be used as either service equipment, or as subpanels, by removing a bonding jumper as I described.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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You betcha. I encourage you to ask your local firemen. They will be happy to tell you some stories.

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Yes.
See here for one example:
http://www.douglassclan.com/ManufacturedHomeDanger.html
-- "We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"
Tim Douglass
http://www.DouglassClan.com
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Tim Douglass wrote:

Ouch! I stopped to read that page, thinking it might have something interesting or that I hadn't come across, and indeed, it did. The amount of misinformation there is large, especially with the assumed theories that were stated. I don't doubt your initial experience as I've seen it myself, but ... I think you exaggerated greatly and unfortunately made a lot of wrong guesses about what what and why. If you'd like some assistance in updating that page so it's accurate and usable as an FYI, I'm sure there are people here who would assist you in that endeavor, myself included. As it stands, it's a badly expressed example of a bad situation but your understanding of electricity is obviously lacking and in need of improvement.
Reagrds,
Pop`
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wrote:

Please elucidate. I am actually quite experienced with electricity and understand home wiring very well, but I was attempting to explain the issue in a "dumbed-down" way so that it would be clear to anyone reading it. I haven't looked at that page since I put it up a couple years ago, but it passed muster with a couple of electrical contractors who are friends of mine.
If you have corrections I would really like to hear about them. Either post them here or e-mail me.
Thanks. -- "We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"
Tim Douglass
http://www.DouglassClan.com
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hello,
you can start by using 240V like all decent people (read, in the rest of the world (Japan except)) and significantly reduce your risk (with or without a neutral or ground). the main reason is ohm's law (U=RI) coupled with resistance law J=RI and power law W=UI ie: if you divide the Voltage on a circuit by 2, you will need to increase your intensity by 2 and therefore, the energy wated in the conductors (read heat) (of fixed resistance) will multiply by 4. so, for the same 'product' with the same output power, your cables will heat 4 times more in 120V than in 240... so, 240 is much safter than 120V (at least when it comes to burning down your house)...
cyrille
wrote:

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On Fri, 15 Dec 2006 19:41:01 GMT, "cyrille de Brebisson"

Nice thought - I'll have all the makers of electrical equipment in the U.S. change immediately... -- "We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"
Tim Douglass
http://www.DouglassClan.com
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How many houses burn down in the U.S. because of this supposed wiring "problem"? Since I believe most electrical fires are related to equipment malfunctions, faulty junctions and connections ......in fact I've never heard (I don't get out much<g>) of a house burning down from a over heated wire that was properly executed and fuse protected. I'd expect lamps, cords etc. to cause way more havoc than the "in the wall" wiring......fear mongering has its place but can you back it up? Incidently does anyone know why "we" chose 120 instead of 220 as the norm?................Rod
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When "we" chose 120, there was no norm.
scott
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That's clearly nonsense -- 240 is far more dangerous than 120, both in its potential (pardon the pun) to electrocute, and to arc. The claim of reduced heating in the conductors is likewise nonsense: in a properly sized circuit, with proper overcurrent protection, heating in the conductors is insignificant regardless of voltage (i.e. if the conductors are getting hot, it's because they're too small for the load imposed).
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Hello! Hello! Earth Calling Edison and Volta!!!! Come in ???
wrote:

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On Fri, 15 Dec 2006 19:41:01 GMT, "cyrille de Brebisson"

From my time in Asia I know that most countries in the region are 220-240v with the exception of Taiwan. When I asked about it I was told that 220-240 systems are cheaper to run.

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wrote:

is controlled by the amount of resistance on the circuit, with the most basic factor controlling resistance being the size of the wire. If we shrink the wire two things happen; first, less power gets through, and second, the wire heats up at that point.
You wrote this? This is really a 'dumbed down' start. I stopped reading after the above. I'm sure you are experienced with electricity and understand home wiring very well, but your explanation of it needs work. No offense meant. Hank
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On Sun, 17 Dec 2006 04:30:41 -0600, "Henry St.Pierre"

I have no idea what I was trying to say there. I think I just mashed a couple thoughts together. Like I said, this was done quickly. Actually, the basic point there has to be something about smaller wire getting hotter for a given load, which would relate to the small size of the connector in the stab-in connection, which is what gets hot under load. As a matter of fact, the use of stab-in connectors is either banned or strongly discouraged in many areas now.
Re-reading that article there are a couple places I need to clean up. -- "We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"
Tim Douglass
http://www.DouglassClan.com
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Since this over milked subject won't die a natural death, I finally had to throw some gasoline on the fire. ---So:--- (1) "Also note that the amount of electricity that can flow....." Electricity having two attributes i.e.; Voltage and Current I shall assume you're referring to Current in this context?
(2) "with the most basic factor controlling resistance is the size of the wire." I shall agree if we ignore the type of material the wire is made of such as lead, copper, silver, gold, tungsten, aluminum, etc-ad-inifinitum. Just ask the toaster manufacturers !
(3) Are we now going to add surface current flow to our consideration of wire sizes to power our tools? And do we ignore the mechanical strength solder adds to a joint? Further, very few, in fact none of my stationary power tools run on DC, so I shall conclude that is "safe" to delete surface current comparisons of AC vs DC from this highly over technical evaluation of what started out as a simple.... Yes/No question?
But at least the Engineering theorists sure had fun with it didn't they? Not a lot of practicality here for application in the home shop , but a lot of smoke got blown and a lot of chest got beaten on!
Don Dando
wrote:

and bring something to kill"

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Toller wrote:

I don't know if it could cause a fire, but if you use a wire guage that is too small, the wire will definitely get very hot. Obviously, if not wired correctly, there's a possibility that the electricity can arc, causing sparks which could ignite something.
But you're right, if done with care and common sense, wiring really isn't dangerous.
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I have to disagree with you on several counts.
First, "common sense" unfortunately is not nearly as common as it should be.
Second, and more important, 120V and 240V alternating-current *is* dangerous, at least potentially so: if mishandled, it can start fires, or electrocute. To handle it "with care" requires a knowledge of the potential dangers, in order to anticipate and avoid them. Far too many people decide to work on their own wiring, lacking that knowledge -- and further lacking the awareness that their knowledge is incomplete. Thinking they know what they're doing, they create dangerous conditions unknowingly.
Third, some dangers cannot be anticipated solely "with care and common sense". Some examples: - Why is it important that the equipment grounding conductor for a circuit be run in the same cable or raceway as the circuit conductors? - Why must ground and neutral be bonded at the service entrance and nowhere else? - Why is it OK to install a 20A receptacle on a 15A circuit, but not a 30A receptacle on a 20A circuit?
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Doug Miller wrote:

You've got me on this one. If I have two PVC conduits going from the panel and put the hots in one and the ground in the other, and the equpment is grounded properly, I'm at a loss as to what could happen.

According to this
http://www.passandseymour.com/knowhowfaq/showquestions.cfm?faqcategory=Electrical%20Basics
it's *not* okay to install a 20A receptacle on a 15A circuit.
Chris
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