Another suggestion a little more expensive but works good when using standed wire.
Use a Spec. Grade device. they have clamps to secure the wire rather than try and twist around a terminal screw. Much more secure.
Same situation if your using #12 AWG wire, the terminal screws on a standard device do not tighten down very good on #12.
Remember whenever the device is used there is a small amount of heat generated at connection points, therefore there is expansion, when it cools the tension on the wire may not be the same and over time.... Loose connection and well... who knows.
Just my two cents
