Back-Stab Switches and Receptacles

I have seen way too many problems with light switches and power outlets when push-in connections are used for wiring into the backs of these devices.  Known as back-stab connections, these are quicker and easier to use and are often convenient to minimize the need for pigtail splices, but this comes at the expense of reliability.

With back-stab wiring, the stripped ends of the wire are simply pushed in and an edge clamp holds it in place.  Unfortunately the surface area for wire contact is minimal and prone to long-term corrosion, especially in damp areas (outdoors, kitchen, bath…).  This makes for a resistive connection which is made worse by a heavy load current.  The connection can heat and melt or embrittle the plastic housing.  If the box isn’t deep enough, back-wired devices also exert more pressure on the connections because the wires are pointing straight back from the rear of the device.  These factors tend to make the connection come apart so that the circuit breaks.  In the photos below, you can see how one wire broke loose completely and the other is barely attached.  You can also see the darkened surfaces where the wire got hot from a poor connection.

Switch failed because housing broke around overheated back-stab wire

Rear view of failed switch. One wire is gone and other is barely attached.

The best and proper way to connect to switches and receptacles is the old method of wrapping the wire around the screw.  If you need to replace a device, consider doing this instead.  Make sure to strip and wrap correctly (clockwise).  See photo below for this technique.

Properly terminated side-wired switch

Good side screw-clamp back-wire switch terminals

Alternately you can use a more expensive back-wire device which actually clamps the wires (not back-stab).  Here the wires are still pushed in the back but in this case they are actually clamped from the side by a plate tightened with a screw.  This is standard on most GFCIs and available on some switches and receptacles.

Properly terminated back-wired switch.

Tags: back, outlet, receptacle, stab, switch, wire