The first thing to find out is if the two 30 amp services are on seperate
circuits i.e. 120/240 or just straight 120 volt, same feed circuit. It would
only make a difference if you need 240volt power for something.

This adapter is made to take two 30 amp sources and combine them onto a
single 50 amp cable. Each 30 amp outlet must be on a different leg. Hubble
makes the best and their prices have recently dropped below Marinco's
prices.

Their unit will not work if the 30 amp outlets are on the same leg. There is
a box below the "Y" which has an LED to tell you the status.

Ron Rogers