[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

[PBRSTREETGANG]

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

[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?

[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.

[1rudeboy]

Would you leave the safety "off" your weapon because you know there isn't a round in the chamber?

That being said, I used to sell electrical distribution equipment. One day, a contractor came in somewhat shaken. He was doing an easy job, and almost forgot to check if the circuit was "hot." Turns out that the entire house was wired with the black and white wires reversed. He'd been in business for 30 years and never seen anything like it.

That being said, when I was in college, I wired/installed a ceiling fan "hot." Not for the faint of heart, and you need to get used to working (primarily) with one hand.

[VRing]

The last time I did this my wife walked into the (semi dark) room and, you guessed it, turned the switch on.

[RightWhale]

If you are alone in the building you may just turn off the switch. If there is another electrician or other person in the building turn off the breaker. For consistency and so that you need not worry it is best to habitually turn off the breaker.