Electrical

Swimbo wanted a new decor light switch. I switched off the circuit at the breaker board. While changing the switch I touched the live to either the neutral or ground with a pliers. There was a good flash with sparks. I did not believe this. I put a meter across the live and ground (and neutral). All volts were zero. I tested again by connecting the live to the neutral or earth with the pliers. No effect this time.
So what gives? How can a residual voltage be contained in a circuit disconnected at the breaker?
I completed replacing the switch, switched on the breaker and everything works ok.
Peter.
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There is no residual electricity, you probably switched off the wrong breaker or there was a second live circuit in the box

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Agreed,
When you went back to the breaker box, did you find an additional breaker in the tripped position?
A neon light or meter between each combination of 2 wires is a good CYA test.
GFCI usually trip with much less drama at least hot or neutral WRT ground. Hot to neutral may could tripped the breaker and left a GFCI still set.

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PVR wrote:

Maybe somebody flipped the breaker back on. And are you sure you flipped the right breaker?
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I always introduce a intential short to check for such mistakes as triopped wrong breaker or the dreaded this box contains 2 seperate live circuits fed by 2 breakers.
better its a screwdrver frying than me flying across the room............
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Better still to use a voltage detector. An intentional short?!
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snipped-for-privacy@aol.com posted for all of us... I don't top post - see either inline or at bottom.

This just adds to the other fundy answers and comments elsewhere. Avoid this guy.
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Tekkie

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Hey its not funny to get hit bad, where a quick no spark assures your not about to work in a hot box.
I have also worked on high voltage devices, better safe than sorry.
So you think my redundancy stuff is funny?
Think about that the next time something essential breaks in your home. My best friend has had 2 washers and 2 dryers for over 30 years that I have known him.
This summer I am drilling a water well in my back yard, for irrigation and back up of city water. my hydra drill knock off is in place.
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Voltage testers work even better -- and it's cheaper in the long run to buy one voltage tester than to keep replacing burned-up screwdrivers.
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Doug Miller (alphageek at milmac dot com)
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wrote:

I think the point was the screwdriver was the "last ditch" check for safety. I do use a voltage tester but I still also short the conductors if I intend to actually touch them (as you know touching is not always necessary when replacing a fixture). I also do this with DC circuits particularly with large caps.
I don't believe he was recommending it as a first line for tripping breakers
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no the screwdriver short is the last test to make certain its dead.
every now and then you find a surprise, better the screwdriver than me!
lways turn breakers off, just occasionally you cant be certain you have the right one
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That is why I always wear sneakers, leather gloves and safety glasses when working in the breaker box. Worse case grounding a bus bar -- 100 A can melt quite a bit of metal and spat it towards you.

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@nospam.adelphia.com says...

What all is on the circuit? Anything that would include a large capacitor?
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snipped-for-privacy@phred.org is Joshua Putnam
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Many answers, for which I'm grateful. None of them applied except possibly yours. On that 15 amp circuit there are a number of 4ft (80 watt) fluorescents but collectively well below the 15 amp maximum. All these lights were ON when I tripped the breaker. Could several starter circuits store up some energy?
Many thanks for your suggestion.
Peter.
is Joshua Putnam

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PVR wrote:

Did any other breakers trip when you got the sparks?
Was there voltage across the neutral and ground?
Could be part of an Edison cicuit. http://www.phy.ornl.gov/divops/ESH/98-2.html
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Sometimes neon bulbs dont light, meters flake out but a nice screwdriver to ground is 100% positive the circuit is dead.
one day I found a bad breaker that way it never tripped. would have never known if I hadnt intentionally shorted test.......
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