| Author |
Message |
    
themp
Citizen
Username: Themp
Post Number: 574
Registered: 12-2001
| | Posted on Saturday, February 28, 2004 - 10:19 pm: |     |
I was going to replace the hanging, cheap looking chandelier in my den. It works on one switch (not a three way set up). I turned it off at the wall, turned on sufficient alternate lighting to work (barely), climbed up on a chair, started feeling around to see how the screw slots were oriented to take it down, and got a real good shock through both arms and upper body (short answer is flip the breaker at the box like you're supposed to, not just the wall switch. I know! Now I'll remember.)
But why did it happen?
It wasn't grounded right, plus it had a short? But why did it have current at all? Reversed polarity?
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ken (the other one)
Real Name
Username: Ken
Post Number: 158
Registered: 5-2001
| | Posted on Saturday, February 28, 2004 - 11:47 pm: | |
It's hard to explain, but....
usually it should be wired like this:
power
switch
light
turn the switch off, no power to light.
what could have happened is that it's wired like this:
power
light
switch
where the hot wire by the light is sent to the switch, and then sent back through the nuetral as a 'hot' white wire, to the light.
So even turning the switch 'off', you still have a hot wire at the light. Safe bet is to always turn the breaker off.
ken
There's nothing like being on the bottom of the Ocean! |
Chasm
Real Name
Username: Chasm
Post Number: 158
Registered: 6-2001
| | Posted on Sunday, February 29, 2004 - 12:11 am: | |
Very possibly the polarity was reversed. I found similar problems (and received a similar surprise)with some light fixtures in my house. The neutral (white) was connected to the switch instead of the hot (black) wire. (Whoever did that was an idiot.)
This is a bad, bad situation. Unless you can positively identify where the swap occurs, don't try to fix it yourself - you may end up inadvertantly connecting the hot and neutral wires together. Call an electrician!
thirdgearrocks |
wharfrat
Citizen
Username: Wharfrat
Post Number: 990
Registered: 6-2001
| | Posted on Sunday, February 29, 2004 - 6:05 am: | |
Having done this for a living way back when I can confirm what the other Ken and and Chasm said: The switch controlling the light was connected to the neutral.
In old houses like ours use caution and common sense. Turn off the beaker and then use a circuit tester. The cheapest costs about $3. If you do more than an occasional switch or fixture get a combination tester that will test and identify low and line voltage. A good one costs about $35.
More often than not what Chasm calls the "swap" occurs in the box in the ceiling. Use a decent circuit tester to confirm this.
Also, DO NOT USE a metal ladder! Wooden or fiberglass ladders have greater resistance, and they lessen the amount of current flowing from the electrical device, through your body to the ground.
BTW, when I used to get shocked the severity of the jolt could cause peculiar perceptual responses. Sometimes during "an event" everything and everyone around me looked like a cartoon.
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Richard O'Connor
Citizen
Username: Roconn
Post Number: 168
Registered: 6-2001
| | Posted on Sunday, February 29, 2004 - 7:27 am: | |
Additionally ... it is very common to find the power (on) at the junction box where the fixture is attached then just 2 wires run down to the switch. This is true of almost EVERY light fixture in my house (and many others in the area I've worked in.)
Based on my reading of your shocking experience, you got the shock before you even started taking things apart. This means one of two things:
1_ Somewhere in your home (it does not have to be this box) there is a fault in the wiring which is sending current to Neutral or ground OR
2) one of the screws holding your fixture up cut/scraped through the 'hot' insulation and went live. (although the box should have ground and this circuit should be blowing constantly.
ONE of the things I have found in almost EVERY CASE where I have worked on electrical in this area is that many of the older homes (mine included) the wiring is cotton wrapped rubber insulation over copper wire. Where this WAS great stuff (and when undisturbed is NOT a problem) but when you start working on it the rubber breaks apart and flakes off (due to rot).
It is EXTREMELY easy in these boxes to get all kinds of 'interesting' things going due to missing insulation and there are some repairs that can be made to solve the issues WITHOUT having your home re-wired.
What I have done in many cases (particularly in gang switch boxes (of which I have many) is to take all the old wires, wirenut them together with an appropriate 'jumper' of new wire and then after twisting on the wirenut, wrapping the whole assembly in appropriate colored electrical tape. (IE .. white on white, black on black, red on red (yes, you will find red and other colors even in 110VAC). Then after the wrapping you tuck the old wires as far back in the box as you can and then have just the 'new' wire(s) for working on.
Make sure when your 'packing' all this wire back in the box (some of which by today's code are a little (way) too small for what they do) that you remember that the METAL screws which hold in the bracket, switch, device go through little holes and down the sides...make sure you keep this area WIRE CLEAR ... or voila ... snap bang flash 
Hope this helps ...
(oh, yeah, I never start playing with electrical without puting on a pair of heavy leather gloves for insulation)
And the Fibreglass, wood ladder suggestion only makes a difference if you are somewhere where the ladder can complete ground to ground.... your hardwood floors are not "ground" .... your flowerbeds are
Richard (ROC)
--Never be afraid to try something new. Remember, amateurs built the ark; professionals built the Titanic.--
--AIM: ROConn |
kevin
Citizen
Username: Kevin
Post Number: 209
Registered: 2-2002
| | Posted on Sunday, February 29, 2004 - 10:03 am: | |
Just remember that 1/10th of an amp can kill you! (that's 100 milliamps).
It can also be done with as little as 30 Volts.
Most of your appliances run on about 120 volts AC.
be safe. |
themp
Citizen
Username: Themp
Post Number: 576
Registered: 12-2001
| | Posted on Sunday, February 29, 2004 - 11:03 am: | |
Thanks for all the detailed answers. I have at least one reversed polarity outlet in my house, and I know that a lot of work was done by a non-electrician. Ive got one ceiling light that just has wires running though a hole in a sheet of plywood - no box or anything. also - my high hats in the kitchen seem to blow out bulbs more than they should.
The lamp that shocked me blackened a bulb the other day, come to think of it.
I think I'll get an electrician in to look it over. I recently spent a bunch to have my second floor rewired, and I had hoped to get that guy to really look over other things, too, but it didn't work out.
I was standing on an upholstered chair at the time (pretty lame, I know. I have to do these jobs in little busts of energy and free time - I urethaned a bannister in my pajamas this morning).
Thanks again. |
jamie
Moderator
Username: Jamie
Post Number: 449
Registered: 6-2001
| | Posted on Sunday, February 29, 2004 - 6:03 pm: | |
Themp -
http://veepers01.budlight.com/service/RetrieveCard?id=4E13D500-6B0B-11D8-9135-E3 635E514682 |
themp
Citizen
Username: Themp
Post Number: 580
Registered: 12-2001
| | Posted on Sunday, February 29, 2004 - 7:31 pm: | |
I had to upgrade my browser to see that.
Warm weather today, Jamie. I saw some people out there plaing tennis.... |
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