Community Forums

Ldduck · 05-13-2019, 07:52 AM

Hello. I searched the internet and came up with nothing. I have a working dryer outlet like the one pictured. I am looking for an adapter that would allow my trailer plug to work with it. Anyone know where I can get one?

450Donn · 05-13-2019, 07:56 AM

Do it at your own peril. Others have done it and it has would up costing thousands to fix the RV. RV 50A is not the same as dryer 50A wiring.

KanzKran · 05-13-2019, 08:08 AM

Quote:

Originally Posted by Ldduck

Hello. I searched the internet and came up with nothing. I have a working dryer outlet like the one pictured. I am looking for an adapter that would allow my trailer plug to work with it. Anyone know where I can get one?

Nowhere, because they don't exist. That dryer circuit is 30A 120/240V and ungrounded (NEMA 10-30R receptacle). You need 30A 120V grounded (NEMA TT-30R receptacle). You can't adapt one to the other in this case, as to get 120V (which your trailer requires), you won't have a ground when using the hot and neutral (the third blade is another hot).*

You can have an electrician reconfigure the same conductors in the panel to get 30A at 120V, and replace the receptacle with a TT-30R receptacle, so you can plug your shore power cord directly into it. But then you can no longer use it for a clothes dryer.

*Existing has two hots and a neutral. You need one hot, the neutral, and a ground. You can't get the second from the first without rearranging some wiring in the panel and changing the receptacle to the proper configuration.

1bigmess · 05-13-2019, 09:00 AM

tl;dr DON'T DO IT! It's not the right power source for your RV!

Sbrownstein · 05-13-2019, 09:01 AM

Quote:

Originally Posted by KanzKran

...*Existing has two hots and a neutral. You need one hot, the neutral, and a ground. You can't get the second from the first without rearranging some wiring in the panel and changing the receptacle to the proper configuration.

Nope, not that it matters for the OP. A 3 pin 30 amp dryer outlet has two hots and a GROUND...no neutral.

tuffr2 · 05-13-2019, 01:42 PM

I had a new circuit run for my trailer. I used all the words needed to have the electrician understand this was for an RV. I told him I wanted it wired just like a campground electric pedestal that a RV would plug into. I also found an electrician that had an RV so he fully understood what I wanted.

So to be safe ask the electrician you end up hiring if he has a camper. If not, call another electrician. It really helped that that they fully understand what you want.

KanzKran · 05-13-2019, 03:29 PM

Quote:

Originally Posted by Sbrownstein

Nope, not that it matters for the OP. A 3 pin 30 amp dryer outlet has two hots and a GROUND...no neutral.

That's a very common misconception, but pre-1996 code cycle dryer and range circuits were allowed to use 3-wire ungrounded circuits, terminating at a 3-pole, 3-wire, ungrounded receptacle (no ground pin). The term "pole" in these NEMA configurations refer to current-carrying pins/blades. The typical NEMA 10-30R receptacle is a 125/250V, 3-pole, 3-wire, ungrounded receptacle. The dryer frame is bonded to the neutral with a jumper. Remove the bonding jumper and the dryer still operates. Remove the neutral, and it will not operate, since it carries motor, lighting, and usually control current.

The whole idea of the equipment ground is that it doesn't carry current during normal use, while all three conductors to a dryer (or range) do carry current, and all the bits in the chain are designed to support that. It's not just semantics, as a neutral is designed and intended to carry current continuously, while an equipment ground only has to carry current in the event of a ground fault, in which case it carries a LOT of current for a very short time (like one cycle or less) in order to trip the breaker or blow the fuse, thereby clearing the fault. Even a small conductor (compared to the current-carrying conductors) will carry a huge current for a short time, and in fact NEC Table 250-95 shows 'small' grounding conductors for relatively high current circuits, like 10 gauge copper for up to 60A circuits.

Post-1996 circuits added the fourth wire to the circuit, making the receptacle a NEMA 14-30R, which is a 125/250V 3-pole, 4-wire, grounded receptacle. The 3 poles are still current-carrying, but the added 4th wire is the Equipment Grounding Conductor (EGC), which carries no current during normal operation, and that pin is not nearly as heavily constructed as any of the three current-carrying poles.

Confusion often comes in the form of the terminology, as the NEC refers to the neutral as the "grounded conductor", while the ground is the "equipment grounding conductor". They may both terminate at the same place in a panel (service equipment only, not subpanels), but by design, all of the components of the grounded conductor (neutral) pathway are designed to carry current continuously, just like the ungrounded conductors are (NEC-speak for hot conductors), while equipment grounding conductors (grounds) and components are not designed for continuous current loading.

Sweetbriar · 05-13-2019, 03:42 PM

Quote:

Originally Posted by KanzKran

That's a very common misconception, but pre-1996 code cycle dryer and range circuits were allowed to use 3-wire ungrounded circuits, terminating at a 3-pole, 3-wire, ungrounded receptacle (no ground pin). ,,,,

So what would happen if the OP somehow plugs is trailer into the outlet he has shown and described?

KanzKran · 05-13-2019, 03:54 PM

Quote:

Originally Posted by Sweetbriar

So what would happen if the OP somehow plugs is trailer into the outlet he has shown and described?

If his home-made adapter grabs X and Y from the 10-30 receptacle, he'll put 240V on his circuits and that won't end well. If he grabs X and W, or Y and W, he'll get 120V on the circuits but no ground, unless he connects the other 'hot' conductor to the equipment ground in his adapter, in which case the circuits will still have 120V on them, but every metal thing that's grounded will be at 120V. So he can either burn everything out at 240V, or have 120V but no ground.

Easy to reconnect in the panel for 120V and change out the receptacle for the proper grounded 30A RV variety, though.

Solo_RV_Guy · 05-13-2019, 03:54 PM

Quote:

Originally Posted by Sweetbriar

So what would happen if the OP somehow plugs is trailer into the outlet he has shown and described?

It's not physically possible to mate a TT30 to the NEMA 10-30 without some really excessive force, or cutting/bending the pins. That's the good news. The bad news is that some well meaning helper would replace the 10-30R with a TT30R or the TT30 plug with a 10-30 plug.

The most likely result would be the electrical destruction of anything expecting 120v... Microwave, inverter/charger, air conditioner (when turned on). The techs that fix such things call this a "release of magic smoke" incident because when you see the smoke come out, the device is no longer operational.