Relay to switch AC?

Question

Say I make a circuit which turns on a house lamp. How do i connect the relay to the lamp. I know how a relay works and the connections but should I chop the lamps power chord in half and connect the relay that way?

Answer 1

I would go to the hardware store and get a short extension cord.  Cut it in half and wire it to the relay, preferable in a metal box.  This way you don't destroy the lamp cord and if you change lamps you just unplug it and replace it.  This technique works well with a light dimmer to control the heat of a soldering iron.

Hope this helps.

D.bumstead

Answer 2

If your relay has two sets of contacts, then yes, you can wire it so that one set of contacts is in each of the power lines to the lamp (live and neutral). DON'T switch the earth connection if there is one - that should be connected all the time.

If your relay only has one contact, then use it to switch the live line to the lamp.

Answer 3

If you have a double pole relay, then yes. Normally a single pole relay would be used, in which case you place the contacts of the relay in series with the hot line of the lamp.

A double pole relay would improve safety if the lamp cord is plugged in backward (which would reverse the hot and neutral wires) because both lines to the lamp will be disconnected when the relay is open.