I have a question about light switch wiring?

For a common "single pole" switch, showing "on" and "off" on the toggle, two wires, two screws, no matter, just put the two wires that were attached to the old switch on the new one, one to each screw.

For a common "duplex receptacle", or wall socket, black (hot) wire to the brass/gold screw, white (neutral) wire to the nickel/silver screw. If not completely confident in past work, use a "receptacle tester" which just plugs in and gives you a read for proper "polarity". If not correct, reverse the two wires (and recheck).

Here's a drawing I did some time ago for a guy who wanted to add a switch to an existing circuit. The black line represents the black wire and is considered the HOT wire. The grey wire in the drawing represents the white wire which is considered Neutral. Notice that the switch does not connect the black to the white wire. Connecting the black and white wires to the switch will lead to a short circuit.

HOWEVER, notice the bottom drawing. It shows an older era of electrical wiring called "Interrupt" circuit. Pay attention to the black wire that goes into the junction box where the light is housed. From there it goes down a single set of wires to the switch. In such circuits you will find only one black wire and one white wire in the box. THAT is an interrupt circuit.

BEWARE! In many interrupt circuits electricians did not pay any serious concern to which side they interrupted. A complete circuit was one that went from the source, through the light and back to the fuse panel or breaker box. Installing an interrupt switch on either the HOT or the NEUTRAL would control the light. The danger is in assuming they switched the hot. I've gotten a few shocks assuming the power was off because the switch was off. Power still flows to ground, and if you touch both you get a shock.

In the modern electrical wiring you will see the white wire come into the junction box where the switch is housed. It will be connected via a wire nut, often orange in color but sometimes black, sometimes yellow and sometimes red. Those white wires are connected to complete the circuit. The black wires (two of them) go to the switch. One to each screw. The switch either completes the circuit and the light comes on or it disconnects the light from the power source. THAT is code.

The principal is the same for an outlet. If it's controlled by a switch it should still mirror the "Original Wiring" diagram. You can imagine an outlet instead of a light. But the wires still need to be connected correctly.

Finally a warning: SHUT THE BREAKER OFF BEFORE YOU MESS WITH THE WIRES. FAILURE TO DO SO CAN RESULT IN A SPARK THAT COULD LEAD TO A FIRE, A SHOCK THAT COULD LEAD TO A NASTY BURN OR A SHOCK THAT CAN RESULT IN DEATH!

If I scared you - good. That's my intention. It's important you understand the nature of electricity and manage it safely. Otherwise, if I failed to mention these warnings and you followed my advice, which may have resulted in damage or injury you would want to hold me liable. I don't want that responsibility. So be careful. And only attempt something if you fully understand what it is you are doing. Otherwise seek the assistance of someone who knows these things. Not someone who THINKS they know, someone who KNOWS.

ME? I'm not an electrician. But I did stay at a Holiday Inn. Actually, I made my living as an electrical / electronics engineer on aircraft and spacecraft.

For safety reasons, minimize the amount of hot/live wires. This means that the HOT wire should be switched, and the neutral should continue through.

Many houses, decades ago, were wired so that the switches interrupted the neutral, which allows the hot wire to go all the way to the light or plug. This means that even when the light is turned off, one can be injured by the hot wire.

It does indeed matter which wire is switched on and off.

On a standard switch it does not matter. On receptacles brass colored goes to hot or black, red, or blue. Silver screws get ehite wire known as the neutral.

Hi there,

If you are searching for Black