Originally Posted by Bronco638
I would have to take the panel cover off to determine how many amps the circuit is but I'm thinking it's 20A.
I am not an electrician but I routinely have a need to pigtail into strange boxes. You should be able to tell by looking at the breaker. It will usually say 15 or 20 on the end of the switch. 20 amp is often a little thicker too.