Question about electrical supply to overhead ceiling box

[Toby06]

If there is a single switch, you are OK. Kill the breaker anyway, though.

[Lonesome in Massachussets]

Switch off the circuit breaker.

There are two dangers. The obvious one is someone inadvertently turning on the switch.

The less obvious one is that the neutral is not switched. Often there are are other lights on the same branch (breaker) which share the same neutral. When you interrupt the neutral or return to wire the fan, it can be connected to the hot through a device further up the line.

BTW, get a good basic guide and follow it. Time/Life books are reliable and very informative.

[tacticalogic]

There's still a potential danger of shock with the wall switch turned off.

There shouldn't be any if the switch is wired properly, but you don't ever want to take that chance. There's a "hot" wire and a "neutral" wire. The hot wire will bite you, and the neutral one won't (or shouldn't). If it's wired properly, the hot wire will be going through the switch, and turning it off will stop the current at the switch. If it's not wired properly, and the neutral is switched it will still turn the fan off and on, but the wires in the ceiling box will still be hot even when the switch is off. All the switch is interrupting is the current path back to ground once it's left the fan. -IMHO

[Lonesome in Massachussets]

The neutral can be connected to the hot through a device further up the line. The neutral is not switched. When all else fails follow instructions.

[PBRSTREETGANG]

Careful there...I'd hate to see a thread with an actual "zot".

[tacticalogic]

That too. Either way the answer is still going to be the same - just turning off the switch is not safe.

[Lonesome in Massachussets]

I know a guy with a Ph.D. in EE who likes to do his own wiring who didn't pull fuses, until I pointed that out to him. IMHO, you're better off with a Time/Life book than a Ph.D. in Electrical Engineering.

[tacticalogic]

I will admit to having done it on occasion, but everything got checked with a meter and then "short tested" before I touched anything.

[labette]

[Rome2000]

Whatever you do, DO NOT CUT THE BLUE WIRE!!.

[NonValueAdded]

Because the typical wall switch only interrupts the connection on one of the two wires. If it was properly wired, that would be the "hot" wire, and you would be OK. However, if it was wired backwards, then all the wall switch interrupts is the neutral wire and one of those wires you will he working with will be live. Use an aluminum ladder, make a connetion to ground, seeeeeee ya. Why take the chance?

And that's only one way that current could still be present when the wall switch is off.

[thoughtomator]

Sorry, why not take the extra precaution of pulling the circuit breaker to make sure you don't end up as a crispy critter?

[Lonesome in Massachussets]

The meter won't indicate any potential until you interrupt the ground, at which time you may be dead.

[Lonesome in Massachussets]

Undoubtedly a Ph.D. EE.

[tacticalogic]

Wire nuts are removed, and all wires separated and tested for potential individually. I don't see where the meter can miss that.

[Dumpster Baby]

All of the above answers are correct. You CAN get zapped on a circuit even with breakers and switches turned off. I've been working in electronics and electrical stuff since 1964, and I *usually* change out light switches and wall sockets at home with the juice turned on - BUT I'm always fully aware of which wires are which, and I don't allow myself to get between two poles of a circuit or between the circuit and ground. I act like a bird sitting on a high voltage line, which is pretty safe as long as the bird doesn't touch anything else at the time.

When I've worked in the capacity of an industrial electrician, everything is done by the book - padlocks and lockout tags on the circuit breaker or switch, probe the circuit with a voltage detector AND a voltmeter, before touching anything that might be live, don't work alone, etc, etc.

[Lonesome in Massachussets]

You have to handle the wires to separate them. As soon as the neutral connected to a live fixure is separated from the neutral connected to ground, it is hot.

I know that if "you know what you're doing" you can do this safely, but the folks who really know what they're doing follow the rules.

[tacticalogic]

I've never done this except in the case of a single-ended switch leg, with nothing downstream. I understand it's not "good practice". Not sure if I've made a bigger mistake by doing it or by having admitted to it.

[Lonesome in Massachussets]

Psst, I dun it, too. I won't do it again and would *never* recommend it. The older I get, the more I learn that the fewer balls in the air - the fewer corners you cut - the easier it is to finish successfully and unscathed.