I looked at a job the other day where a single pole switch controlled a light. When the switch was in the down position, it said on, but the light did not work. With the switch in the up position, it said off, but the light worked. How is that possible? Does anyone want to take a stab at it?

If the switch is upside down, in the on position it would say no. And in the off position it'd say ffo. I suggest installing a new switch and install it the correct way. That's what I would do.

That's funny!

That sounds like it might have been part of a photocell (or other) controlled lighting contactor circuit. I can think of numerous scenarios. I have a nasty habit of taking markers to unlabelled switches, disconnects, Et,c.
Joe

Mercury switch installed upsidedown?

2 way switch miss-wired as single way?

edit, [I just woke up, no coffee yet!]
Alan

[This message has been edited by Alan Belson (edited 04-04-2006).]

American 2-way switches (3-way in U.S. terminology) have unlabeled toggles though.

Only simple 1-way switches have "On" and "Off" marked on the toggle.

I'd have to agree with Mr. Wise: upside-down mercury quiet switch.

Could just have been a bad day at the switch manufacturer, and the toggle was installed upside-down...

NJW, you got it right. I went back to do the job that I looked at and had to replace that switch, that's what it was. I should have kept that switch.

I would have saved that switch..and installed as many times as needed or until I was satisfied I had "fooled" everyone

Same here. One old series of toggles had a red dot for "on", the 3-way and 4-way were just white (by the way, in German 3-ways are call alternating and 4-ways cross switches, because they alternate between the two travellers resp. cross out the travellers).