I removed my nutone door chime transformer a while ago to work on an electrical problem. Now i want to reinstall it but don't have the instructions. The transformer reads nutone class 2 LR2982 10va 16v

I couldn't find a manual for the LR2982, so I'll give a general description of how to wire a door chime. Most chimes have 3 contacts. F (Front), R (Rear) and C (Common). Some have just two contacts. If your chime has more than 3 contacts do _not_ follow these instructions.

Inside the junction box on the wall where the chime will be mounted, you should have at least 2 cables (usually brown) each, with at least two wires (usually red and white) each. One of those cables goes to the transformer and the other cable goes to the door button.

The beauty of it is that since it's only 24 volts or less and _polarity_ doesn't matter, you don't need to know which cable goes where for a _single_ door button scenario.

For _single_ door button wiring, pick a wire (say the red) from one cable (doesn't matter which cable) and connect it to the "C" contact on the chime. Pick a wire (say the red) from the _other_ cable and connect it to the "F" contact on the chime (if the chime has 3 contacts). If the chime only has 2 contacts connect it to the only contact that is left.

Then all one needs to do is twist the 2 remaining wires together (both white) and cap them off with a wire nut.

If your junction box for the chime has 3 cables in it, the extra cable goes to a rear door button. In that case you _do_ need to know which cable goes to the _transformer_. You can pick up a cheapo voltmeter for about $10 just about anywhere. The cable that reads anywhere from 16 to 24 volts AC between the red and the white wires is the cable that goes to the transformer.

Make sure one of those wires from the transformer goes to the "C" contact (pick one, say the red). Now you know the 2 remaining cables go to the front and rear door buttons. For now, just connect a red from one of the remaining cables to the "F" and one red from the other remaining cable to the "R". Then just twist the 3 remaining white wires (including the white wire from the transformer) together and cap them with a wire nut.

If the rear chime sounds when the front door button is pushed, just swap the wires on "F" with the "R"contacts..