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Discussion Starter #1
I always turn the breaker off when I do any electrical work, earlier this afternoon my father in law when to my wife's work to install a new light fixture basically all he did is turn the light switch off and started the wiring well we can all figure what happened next. He came home with a black thumb and was saying sparks were flying not much surprised there. Now I was thinking since the switch was OFF how is it possible to get electrocuted? Is it that the wires are still energized? Basically the HOT wire is broken by the switch when the switch is in the OFF position so how is it possible that current can still flow into the rest of the circuit?
 

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Master Electrician
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Older homes were wired to switch the neutral. Additionally, if the switch is in a loop, power is still present at the ceiling box.
 

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Discussion Starter #3
That's a new commercial building!! I wonder if he didn't just turn the dimmer switch all the way to OFF!!!!
 

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There's still power to one side of the switch, even with it off.
 

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I always turn the breaker off when I do any electrical work, earlier this afternoon my father in law when to my wife's work to install a new light fixture basically all he did is turn the light switch off and started the wiring well we can all figure what happened next. He came home with a black thumb and was saying sparks were flying not much surprised there. Now I was thinking since the switch was OFF how is it possible to get electrocuted? Is it that the wires are still energized? Basically the HOT wire is broken by the switch when the switch is in the OFF position so how is it possible that current can still flow into the rest of the circuit?

If power goes to fixture first,
Then it goes to switch (switch loop),
this would explain why there is still live wires at fixture !

This is why properly trained people turn off power first !
Then test it to be sure its off !
Make sure he does this, next time !
 

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Semi-Pro Electro-Geek
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As DMX noted, if it's wired as a switch loop then there is always power at the fixture and at the switch, no matter whether the switch is on or off. If it's not wired as a switch loop, then there should not be power at the fixture unless the switch is on or the circuit is miswired by switching the neutral. No matter how it's wired, there is always power at the switch. Bottom line: turn off the breaker!
 

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Licensed Electrical Cont.
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There's lots of ways for power to still be at a box even with a switch off. Sorry, but he was a complete fool for doing this, AND for working in a commercial space without the proper licensing, insurance and (even worse) experience.

Also, he did NOT get "electrocuted". If he did he'd be dead.
Electrocution is death by electricity.
 
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if it is a commercial building it probobly had a emergency light fixture with a battery pack, so at the light there is a switch leg and a constant hot to charge battery pack in case of a power failure via three wire from switch to each light fixture
 
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