Differences Between NEMA 6-50 and NEMA TT-30

Posted by Christopher Hahn on

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In the world of electrical connections, there are quite a few plugs and outlets that
look very similar to each other.  In the past, we have discussed differences in locking plugs and outlets most often associated with generators, and the differences with the outlet and plugs you can find in your home. There is another set that looks a little similar but serves very different purposes. This set is the NEMA 6-50 and NEMA TT-30.
NEMA 6-50 and NEMA TT-30
The confusion usually starts because of the number of prongs each has and the way they are set up. As you can see, they both have 3-prongs. Two of them are flat, while the third is round. Do not assume it will fit based only on looks. In the electrical connection field, there are many different connections. The best way to identify your connections is with the NEMA code imprinted on the plug or outlet. So then what else makes them so different?
NEMA Markings
Let’s start with the NEMA 6-50. This connection is typically used for welders or construction workers that require high power for their jobs, but it is also gaining popularity in the electric vehicle community. The two flat pins are hots, while the round pin is the ground. This means this connection will also be running at 250 volts.
NEMA 6-50 plug
Now, let’s look at the NEMA TT-30. This connection is typically used for RVs that require 30 amps, as the connection itself is named “travel trailer.” You will see this connection at campgrounds and on portable generators. One of the flat pins is hot, while the other is neutral, meaning this connection will be running at 125 volts. You will also notice the flat pins are angled slightly. This is one easy way to tell it is a NEMA TT-30. The ground is round for this connection. In fact, the ground pin is usually round for most connections.
NEMA TT-30 plug
Now, can you adapt from one of these outlets to the other? Not really. The fact that the 6-50 is 250 volts while the TT-30 is 125 volts is the biggest reason. Trying to adapt connections with different voltages never really works.
If you have any questions about other similar looking power connections, feel free to reach out to us with a text, phone call, or email.

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  • Hello Mike. It would actually need to be neutral. The 6-50 has two hots and a ground. In order to get 120V for a 30A RV, you would need a neutral, two hots, and a ground. If your 6-50 outlet has a capped neutral, then yes, it could be rewired for 14-50.

    Christopher on
  • If there is a ground you can convert to a 14-50R which offers many adapter options for 30 amp campers, I just lucked out and did this in my barn.

    Mike Weiss on
  • Hello, Rich. I’m not quite sure how that could be done. 6-50’s don’t have a neutral. 6-50 outlets would only be wired for 250V service with the two hots and a ground. You would need a very weird adapter to attempt to go down to 120V service.

    Christopher on
  • While understanding the limitation at the breaker panel, what is the risk of pulling power from just one pin for a TT-30? I see several adapters going from nema 6-50p to 115 plugs

    Rich on
  • Hello Richard. A lot of people look for that conversion, but it is not possible. A 6-50 is two hots and a ground, making it only operate at 250V. A TT-30 is one hot, one neutral, and one ground, making it run at only 125V. You cannot step down the 6-50 from 250V to 125V because it does not have a neutral wire. You can only step down 250V connections when there is 4-wires present: two hots, one neutral, and one ground.

    Christopher on

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