Well, two wires are the power, black and red for some, black and white for others, and Spektrum/JR have their own color scheme, red and brown I believe.

The signal wire is not a current carrier, but I believe if you do get the HD version of the Hobbico servo extensions, all three wires are the same size or gauge. The main point would be the power or current carriers. They are equal in size and you don't have to figure the two-way current draw as the black - brown - whatever the neutral or ground wire is is the common for the power bus.

The original question was what size wires would be used for an extension for a digital servo that can draw as much as 3200 ma (3.2 Amps). Of course, that's not constant current, but worst case current draw and the Hobbico HD would probably be just fine.

CGr.