Break the Brass Tab When You Replace a Switched Outlet

The Problem

Swapping every receptacle and switch in a house is one of the most common jobs a homeowner takes on — it costs little, it modernises every room at once, and it's an easy win before selling. The method is to work outlet by outlet, copying each set of wires onto the new device.

Somewhere in the house there's usually a half-switched receptacle: the top half live all the time, the bottom half controlled by a wall switch, so a lamp turns on from the door. From the front it looks identical to every other outlet. The difference is inside — on the old device, the small brass tab joining the two hot-side screws has been snapped off, separating the two halves.

The Technique

Look at the tab on every device you remove, before it goes in the bin.

1. On the hot (brass) side of a receptacle, the two screws are joined by a thin removable tab.
2. Tab present — both halves are fed from the same wire. Normal outlet.
3. Tab broken off — the halves are fed separately. Match it: snap the tab off the new device with pliers before you wire it in, and put each wire back on the screw it came from.

Miss it and the result depends on how the circuit was built:

• One circuit, switched half. With the tab intact, the constant-hot feed now reaches both screws, so the switched half is permanently live and the switch controls nothing. It also backfeeds through the switch leg.
• Two separate circuits. Some receptacles are split with each half on its own breaker. Leaving the tab in ties two circuits together through the device, which is a fault — expect a tripped breaker, and possibly a much larger one if both are on the same leg.