Prompted by an answer on Concerns about replacing a worn out light switch
To my knowledge, electrical components (switches, outlets, breakers, basically all the home-voltage kinda things) will have one of the 3 connector types:
- screw wrap - the wire end is wrapped around a screw, and the screw tightened to hold the wire.
- screw down - The wire end is left straight, a screw is tightened to hold the wire, either directly or via a pressure plate.
- push in / friction - The wire end is left straight, and pushed between an angled plate which holds the wire via pressure in the design.
There are many, many variations on these themes (plastic housings, attempts to make a release device for friction fasteners) but they all seem to boil down to these 3. I'd like to know the pros and cons of each of them; but in particular I'd like to know what can or will happen when they fail.
For example, the push-in are fastest to wire.
Other than having to take time to twist the wire end, the two screw options seem basically identical. Okay, it would take significantly more force to pull a wire out of a wrapped connector than a straight one, but I expect we're into impractical pulling force on the wire either way. The straight wire ones seem to be less common though, probably as it's more complex to manufacture.
I see a lot of dislike for the push-in connectors. Personally, I find them a huge pain to re-wire, and it's usually simplest to just cut the wire off and start again. But if something's wired with push-in and working, how can/will it fail? What symptoms, particularly early signs, indicate impending failure?