I have posted some pictures here of how our two Travcos have input power connected to them.
Both Travcos have Kohler 6.5C63 6.5KW water-cooled generators.
The '67 has a 240VAC 4 pin receptacle on the genny and the Travco has a 4 pin plug to insert into it.
The '67 plugged into the Kohler genny.
The worse for wear power cord receptacle to plug the '67 RV into "park" power. The other end of the cord should be a standard 30 amp 3 pin RV style plug. Not shown is that the two 120VAC legs of the receptacle are shunted together.
The '66 built for California has a lockable compartment on the side opposite the generator to access the power connections.
The 3 pin twist-lock plug from the generator (240VAC) and the power input receptacle in the background on the '66. (120V leg, 120V leg, neutral, case is ground)
The '66 with a 30 amp park power cord inserted. Not shown is that the two 120V legs are shunted together inside the plug. (Generator output cord laying beside it)
The end of the 50 amp cord for the '66 that I made. This end matches 50 amp park service.
Ideally, the 3 pin twist-lock on the '66 should be replaced with a proper 4 pin twist-lock that has separate neutral and ground. Then you could use the 4 wire, 4 pin 50 amp cord to connect to a 50 amp park power outlet. If wired like the '67 it would have a 4 pin receptacle to match the RV's plug.
2 days ago