Changing out receptacle that is controlled by a light switch

Question

Help Please! This is the first time I am attempting any electrical project. I changed out old receptacles with new ones in our master bedroom. I used Leviton standard outlets 15A-125V.

Question #1: How come some of the receptacles have 2 white, 2 black and one ground wire, while others have only 1 white and one black wire?

Question #2: The switch to the bedroom controls the ceiling light and the bottom plug of the outlet next to the bed. Now that the new outlet is installed, the switch no longer controls the bottom plug, Why? I wired it exactly like the old one. I did not do any work on the switch. Please help me understand!

Answer 1

Because you didn't look at the old receptacle to see if any tabs were broken off.

You should break off tabs in the new receptacle exactly as you find them in the old receptacle.

Breaking off the tab changes the meaning of the two screws. Instead of "two screws that connect to the same thing and can be used for supplying power onward to other receptacles", it now means "each socket in this receptacle is being fed power separately by a different wire, and each socket gets only one screw". This is used for splitting receptacles for lamp control, and a few other uses.

I have no idea if the old receptacle broke tab off the hot side (brass), the neutral side (silver) or both. You will need to trash-dive the old socket and have a look. Breaking the hot side is the most common. But if neutral had been broken/split before, and you fail to split it now, it creates a "silent but deadly" failure mode that will be revealed only by a fire or GFCI trip.

Answer 2

"Extra" wires

Each receptacle only needs one black (hot) and one white (neutral). However, another pair of wires is often connected in order to bring power to another receptacle as that is much easier (and much less wire) than connecting each receptacle directly to the circuit breaker panel.

There are three ways to connect a 2nd pair of wires.

• Connect two wires to a single screw. Don't do this as it is not reliable (and likely not to code).
• Connect one pair to one pair of screws and one pair to the other pair of screws. White to silver screws. Black to brass screws. This is easy and works great with two exceptions explained below.
• Use a wire nut to connect each pair of wires (blacks or whites) to a short piece of wire (same color) - a pigtail. The other end of the pigtail goes to a screw on the receptacle (white to silver, black to brass). This method will work even if there are more than 2 blacks & whites.

Exceptions:

• A pair of outlets can be split so that one outlet is switched and one is not. In this case there is a metal tab to be removed between the brass screws. If you don't remove this then either the outlet will no longer be switched (which is your situation) or possibly some other strange/bad things may happen (e.g., if this is an MWBC).

• GFCI - If this is a combination GFCI/outlet then the pairs of screws will NOT be interchangeable. Instead one pair will be LINE which must be connected to the power source going back to the circuit breaker, and one pair will be LOAD which can be used to protect additional downstream outlets - i.e., without having to install a GFCI at the other locations.