I will be installing temporary wiring for an RV which has a NEMA 14-50 plug. The RV does not actually need 240v, it just splits the load between two 120v legs. I want to use a 30A 120V circuit breaker, and put a 14-50 receptacle on the end of a cord. A common way to do this is to use a straight TT-30 cord with a 50A to 30A "dogbone" adapter, but in order to have one less connection, I'd like to wire a 14-50 receptacle directly to the cord, like this one.
My question is, how can I bridge the two hot legs inside this receptacle? Is it safe to use a short jumper wire for this?
Best Answer
No. You cannot hardwire a 50A receptacle onto a 30A breaker.
Given your goals (30A single-pole breaker) use either a TT30 receptacle or a NEMA L5-30R.
You are welcome to fabricate your own dogbone adapter, with a NEMA 10-50R on one end and either a TT30 plug or L5-30P on the other.
Inside the homebrew dogbone adapter, I am OK with hooking both 10-50R hots to the same supply hot, but: Be very careful that your RV is not wired with any multi-wire branch circuits. Those will overload the neutral wire in that configuration. Because of this risk in using the adapter in random unchecked RVs, be very careful who you loan that adapter to.