After looking at the 20A wattgate I'm using with my Ref 3 and the pic linked above, I'm not sure there is enough clearance. Check out the wattage's specs at
http://www.wattgate.com/products/350ihcag/
The outside diameter on my 20A extends approximately .3 inches above the width of the insertive part.
http://www.wattgate.com/products/350ihcag/
The outside diameter on my 20A extends approximately .3 inches above the width of the insertive part.