Have a 1500 sqft home (built 1985) with 100 amp service and a load of about 47
amps. We would like to add an electric wall oven (3600 va) which would bring the
load up to 62 amps. The problem is that the breaker box is full. (There are only
16 breaker slots). I know there are side-by-side 15A breakers which take up only
half the space. I would like to put 4 of the existing circuits on the these
side-by-side breakers so I could free up two slots. Once I do that, I can put
in a 240 volt 20 Amp double breaker for the oven.

Question 1: I have seen the side-by-side breakers for Square D but this box is a
Sylvania-Challenger. Are there side-by-side breakers for the Challenger?

Question 2: If not, how much might I expect to pay (very roughly) to have an
electrician (Central NJ) swap out the Challenger for a 20 slot Square D
including the permit, temporary disconnect of power and inspection?