Setting up shore power

[DougW9876]

I have my 2970 (50amp) plugged into a 30amp outlet at home. My Power Watch Dog shows 120v on each leg. Does that mean my outlet is wired incorrectly? If it is what damage could happen and how would I correct it?

Most likely it is not wired wrong. If it was wrong your Power Watch should be showing a missing neutral because a 30 amp outlet wired for 220VAC will have L1 (120VAC), L2 (120VAC) and ground. If it is wired correctly for 120 VAC service it will have L1 or HOT at 120VAC, Neutral, and Ground.

Your adapter will send voltage from the hot side of the 30 amp outlet to L1 AND L2 of your 50 amp cord. If you test with a meter you should read 120VAC from L1 to ground and L1 to Neutral, 120VAC from L2 to ground and L2 to Neutral, 0VAC L1 to L2 and 0VAC ground to neutral. If you are plugged into a 50 amp. Outlet your L1 to L2 reading can be 240VAC which would be normal.

[Jerryr]

In fact I run it on a 14-30R, 30 amp 240 4-wire dryer outlet with a proper adapter at home when loading it for a trip. (You can’t do that on an obsolete 10-30R, 3 wire dryer outlet because it doesn’t have a ground where a 4-wire does)

You are confusing a "grounding conductor" with a "grounded conductor". The obsolete 10-30R would still have a ground conductor (usually bare or green) but not a neutral (grounded conductor) which could be either white or bare.

That’s for the correction. I should have stated while a 3 wire 10-30R outlet has a grounding/ground but not a grounded/neutral current carrying wire.

Did I get it right this time?

I converted my 1996 house dryer outlet from a 10-30R to a 14-30R. Fortunately it had 10/3 NM-B W/G wire run from the panel to the outlet box. It was a simple rewire to convert to a 4-wire 14-30R since I had red, black, white and bare wires.

FYI, I use this adapter below at home to connect my 50A RV to the 14-30R dryer outlet and it works great. I can even run 2 AC units on it since they are on opposite legs.

[SolarPoweredRV]

[QUOTE=Tripleblessing;385587]

One issue that is very common with 30a (TT-30) outlet installs is that they are wired incorrectly by Electricians. The TT-30 connector is the same/similar to a 240 volt residential dryer outlet. Many Electricians have ignored/not remembered that the TT-30 is actually a 120v outlet and not a 240v outlet.

Please ensure your Electrician knows the TT-30 is to be wired as a 120v outlet and that that is specifically written into the contract (so they can't say later that you did not specify 120v [even though it is their responsibility]).

Additionally, I think the responses in the above posts have eliminated one Electrician from your consideration.


I have my 2970 (50amp) plugged into a 30amp outlet at home. My Power Watch Dog shows 120v on each leg. Does that mean my outlet is wired incorrectly? If it is what damage could happen and how would I correct it?

Unless your home outlet was specifically wired for an RV (TT-30 outlet wired for 120v) then you have plugged your RV into a 240v circuit.

The way to test the outlet is with a Volt Meter set to A/C with the voltage set so that 120v falls within the range on the meter (mine has a setting for 200v). Place one prob into one side of the outlet and the other into the center (ground) outlet if you have 120v on both sides of the outlet, then you have a 240 volt outlet. If you have voltage on only one side you have a 120v outlet.

Most 30a to 50a "Dogbones" take the 30a input and split it (internally) in order to feed both legs of the 50a coach. If you do have a 240v outlet I am not sure exactly what is happening (somehow the dogbone is using the ground lug as a neutral) inside your dogbone to let you feed the coach with only 120v on each leg.

If you do have a 240v outlet in your house, I would immediately stop using it for your RV until you can get the outlet wired properly, or get a new outlet installed.

Please let us know what you find.

[IBEW Sparky]

That’s for the correction. I should have stated while a 3 wire 10-30R outlet has a grounding/ground but not a grounded/neutral current carrying wire.

Did I get it right this time?

I converted my 1996 house dryer outlet from a 10-30R to a 14-30R. Fortunately it had 10/3 NM-B W/G wire run from the panel to the outlet box. It was a simple rewire to convert to a 4-wire 14-30R since I had red, black, white and bare wires.

FYI, I use this adapter below at home to connect my 50A RV to the 14-30R dryer outlet and it works great. I can even run 2 AC units on it since they are on opposite legs.

Yup you got it right! And as far as converting the 240V dryer circuit to your 50A RV feeder that will work. I wouldn't put much load on it if while running both ac units or you could trip the breaker

[Jerryr]

Yup you got it right! And as far as converting the 240V dryer circuit to your 50A RV feeder that will work. I wouldn't put much load on it if while running both ac units or you could trip the breaker

I monitor the load with my Progressive EMS display. The 2 AC units are on opposite legs, drawing between 14-16 amps per leg. With both AC units, refrigerator and converter running neither leg exceeds 22 amps. I don’t run microwave or electric water heater when home getting the RV ready for a trip.

[Tripleblessing]

I finally made it this morning to check my 30amp outlet at home. It appears to be wired correctly with 120v on only one leg. Thank you all for the help.