Short Circuits: Why does my 50-amp twist-lock plug only have 3 contacts?
It does have 4 contacts, and here's what you're missing...
Here’s my latest edition of “Short Circuits”
Hey Mike,
Why does the twist-lock plug on my 50-amp RV only have 3 contacts? The plug that goes into the pedestal has 4 contacts, and the diagram you show has 4 wires. What am I missing? - Confused in Connecticut
Dear Confused,
Your 50-amp twist-lock plug does indeed have 4 contacts, but one is not obvious. Here’s how it works…
The 30-Amp Twist-Lock
The 30-amp connector has 3 contacts which I’ve labeled 1, 2, 3 in the picture above. That’s the Hot, Neutral and Ground connections you see in my pedestal testing diagrams.
The 50-Amp Twist-Lock
The 50-Amp connector also has 3 obvious contacts which I’ve labeled 1, 2 and 3. That’s for the Hot-1, Hot-2 and Neutral wires. But there’s also a 4th sliding contact on the outside edge of the connector which I’ve labeled as #4. That’s the ground contact which bonds the chassis of your RV to the incoming circuit breaker panel.
Making Connections….
And in case you’re interested, here’s how a 50-amp shore power cord is wired. But more on that later…
Let’s play safe out there… Mike
Are you all finding my “Short Circuit” articles useful? I sometimes forget just how many unique and specialized gadgets are in an RV.
Yes. I have to give a 20-30 tech talk in July and I'm using some of your pointers. My talk will be basics, like what electrical "toys" to carry with you, plugs, batteries, gadgets. And safety. Probably won't have time for powerpoint or videos. I talked to you a few months back on the phone on this. I got this handled. July 11-14, Rickreall, OR