This is meant to be a general question – I'm not asking about any specific breaker. More of a practical methodology question.
Some breakers are clearly labelled as to whether or not they accept a double tap (two wires under one screw / clamp).
But if there are no markings or they are illegible, which seems to be common with older breakers I have seen, is it likely to be acceptable to assume a double tap is or is not okay based on the shape of the terminal clamp?
In this example there are clearly two 'slots' where the wires are meant to go:
Would seeing such a clamp (or similar) guarantee that this is OK to do?
Best Answer
In my opinion the particular breaker terminal you are showing, is legal for connection of two conductors. The only residential breaker that I know of that has this feature is a Square D Type QO. Maybe a Cutler Hammer Type CH, I think?
Regardless, it doesn't matter what my opinion is unless it is the AHJ agrees. I have had this discussion with local Inspectors many times and I can say that I have won about 50% of the time and lost 50% of the time.
In conclusion, check with your local authorities because what he allows and doesn't allow is really all that matters.