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?
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
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's *not* okay to install a 20A receptacle on a 15A circuit.
Whohoo! I finally post to the wreck. My apologies in advance for the googlegroups thing, the usenet server that I use doesnt allow posting, and I'm too broke to afford a nice subscription to a decent server.
Anyways, My parents had a house built in 1997 (when I was 16 years old). There have been two "near fire" incidents since it was built, on
120v circuits.
The first involved a pathetic "power strip" unit on the end of a bar-style counter in the kitchen. The electrician installed this pathetic plastic rail that was 14" long, and only containted two outlets.One outlet would make intermittent contact, the other was fine. One day in 1998, the unit started smoking a bit, the tripped the breaker. I am quite a handyman, and amateur electronics technician, and have had moderate experience with practical wiring, so I opened the unit up to take a look at it. The bare ground wire had a nice crimped plastic-insulated connector on it (in a matching beige color) and was in fine shape. I don't know what the electrician did with the other two plastic crimp-connectors (that I assume came with the unit) but he had used wire nuts to connect the hot and neutral pigtails to their respective wires (The outlet had pigtails, rather than screws or backstabs). The wire nuts were a hair too large to fit into the plastic rail, so he had taken a knife and trimmed the sides of the wirenuts down. Over time, twisting plugs around inside the intermittent outlet had caused the exposed metal edges of the wirenuts to brush against each other, creating an arc between the hot and neutral lines. This make some good smoke and melted the plastic rail housing a little bit. (That same electrician installed lights in my father's woodshop with a constant hot, a switched ground used as a neutral, and an un-connected neutral, which we noticed and fixed before there was any noticable problem.)
I replaced that mess with a plain old computer-style power-strip, with the plug snipped off, and attached with good wirenuts and secured with a big wad of electrical tape. It has been much more useful and reliable, for the past 8 years.
The other incident was in the attic, which my parents decided to have finished in 1999, into an "apartment style" space (with a bedroom, kitchen, bathroom, and livingroom). I did the entirety of the electrical wiring and electrical finish work, with the help of a BORG how-to electrical code book, and some internet state-specific electrical code research. It was inspected by a county electrical inspector, and passed.
A little over a year ago, (after I had gotten married and moved out) my parents and little brother were watching a movie in the attic family-room. My mother plugged a circulating-oil-heater into an outlet, and a different outlet, behind a couch, started smoking. After dissecting the situation, we found a good third of the blue plastic outlet box had melted, and half of the outlet itself had disintegrated. I had chained the outlets from that breaker together, and that outlet had been the weak link in the chain. It had one cable running in from the previous outlet, and another running on to the next outlet. I had bent a hook in the ends of the wires and stacked the two hooks onto each of the screws (I dont trust the backstab system). That was acceptable according to the inspector. The small contact area between the two neutral wires had not been a problem until that higher-current heater was plugged in, at which point it had exceeded the current-carrying capacity of a contact point with such small dimensions. It proceeded to overheat, melt, arc and destroy stuff.
20/20 hindsight has helped me realize that it's a very good idea to throw a wire-nut onto situations where there is more than one wire, and run a single-wire pigtail out to the screw contact.
The damage was done to the side of the outlet box AWAY from the 2x4 stud, thankfully, partially due to my father's instruction to install the outlets "upside down" so they didn't look like a smiley-face and tempt small children. Had it happened on the hot lead, or had the outlet been installed the other direction, we would most likely have had a fire (according to several expert and experienced opinions).
So yes, it's quite possible for even minor wiring problems to cause fires.
That's ok, but only up to the point where mis-information is being given.
Your point is incorrect. You might want to try exactly what you propose and see what your county inspector suggests.
I think you are assuming too much with this position.
Ok, so now we are back to the beginning of this thread. It seems you have arrived at the same conclusion that your adversaries were at when this started.
Hey Doug - I think that what he meant by "common sense" was the common sense to follow such things as electrical code, and not get all wrapped up in "would-be-nice-if" scenarios. Keep it simple, apply the code, and use common sense with code as your guide line.
Well, perhaps so -- but do you spend much time at alt.home.repair? Seems that a lot of people are unaware that there even *is* an electrical code. And some of the posts in this thread should be more than ample to show that even some folks who know that the Code exists, don't know nearly as much about what it says than they think they do.
Nope. I have to confess total ignorance of that group.
Unfortunately it seems that there are a lot of folks who know a code exists, and then throw out the phrase "Code" as if to support their position, with no real knowledge of what the code even says. I'm the first to admit that I don't have every page of the NEC memorized and I ask from time to time, in order to cover areas that I might not deal with on a regular basis, but I have certainly seen enough of the aforementioned references to code by those who clearly know nothing about what it says. Now *that* is dangerous.
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"
Actaully, that "bodge" is required by the electrical code in US wiring, that or an equivalent. Do you know of any cases in which wire nuts caused fires? What do _you_ use?
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=RI² 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)...
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) 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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