My 2 cents on back stabbing receptacles, i've been on just as many service calls where the original installer forgot to tighten the screw as I have for back stabbed receptacles.
And now it begins !!!
I'm not out to pick on anyone in particular here, just stating my opinion like others have. I've heard this reply more often than I'd like to remember. IMHO, this type of connection is designed for SPEED only. It ranks among the worst possible electrical connections one could make. In all probability the electrician (or helper) that uses back-stabs probably works for a track builder where the price for the job is the same on every house. The faster you finish - the more $$ you make.
Now stop and think about when you buy a switch or a receptacle. The screws on the device are all the way out and are obviously designed to have wire wrapped around them and the screws torked down. Any electrician worth his salt would tork down the screws even if they are not used. If you are the level of electrician that chooses to use the back stab connection on either receptacles or switches consider the fact that those un-torked screws now give you less room (side to side) when either ganged together or installed in a single gang metal JB and make that installation more dangerous than necessary.
Next we have the quality of the stab connection. Duplex receptacles are obviously designed to have "feed-through" connections so, let's say you have 8 or 10 duplex receptacles connected together on a run and you used the back-stabs as your connection method. As appliances are connected down stream of the first receptacle, that first receptacle is taking the heat for the entire circuit. As that circuit starts to heat up the holding fork (for lack of a better term) inside the receptacle heats up and the wire it's holding starts to loosen. When it loosens it starts to arc and, if you're lucky will just pop out of the connection. If you're not so lucky it will burn up the receptacle and possibly start an electrical fire. Can this possibly happen with a screw-down type connection - yes but the probability is a lot less.
Finally, when you think about the quality of a back-stab connection think about why the holes in the backs of duplex receptacles and s/p and 3-way switches have been reduced by the manufacturers to only accept # 14 AWG. Why don't they accept # 12 AWG ? The next time you buy a single receptacle take a look at the back of the receptacle and see if there are any holes or the capability to accept back-stabs. There's a reason. It's a lousy connection method.
