Wiring question

RV Randy · 06-08-2018, 12:33 PM

We're at the track today and it's over 100 degrees. We're surviving by running the AC off of the generator. But I do have access to multiple 20a 110 outlets. I have the cable and cord ends to make up a Y harness to plug into 2 20a outlets and a 50a RV plug on the other. How do I wire this up? I know I wire the hot from the 20s, one plug to L1 and the other to L2, the 2 neutrals are tied together as are the grounds. Am I correct the hots should be black, neutrals white and ground green? Which prong on the 20a plug gets the black? I'm assuming this will give 30a at least into the rig?

babock · 06-08-2018, 12:44 PM

Quote:

Originally Posted by RV Randy

I'm assuming this will give 30a at least into the rig?

It won't. It will put 20A on each of the legs.

I am assuming you already have a 50A service within your RV right?

Kaadk · 06-08-2018, 01:11 PM

If you're not familiar with the circuits you're tapping into, I'd steer clear of attempting this. If end up plugging into two outlets on the same phase, you can end up with 240 on the common neutral.

If it's just for the air conditioners, what about disconnecting them from the coach's electrical, putting 20amp plugs on them and plugging them in directly with extension cords? Each would be on it's own outlet, it's own circuit and isolated from the rest of the rig.

RV Randy · 06-08-2018, 01:14 PM

Yes on the 50a in the RV. As long as each 20a outlet is on a different leg, won't that give 40a total? That's the way a 50a outlet is wired.

CHICKDOE · 06-08-2018, 01:16 PM

this is a tough one to comment on due to all the possible safety issues. you are aware what the results could be with an error in wiring? and then the assumption of what the black, white, and green wires are. no assumptions allowed!

as stated it will put an independent 20 amp supply on each leg. i see three issues with that. the two supplies are not connected into a ganged circuit breaker. so you could trip one leg and still be hot on the other leg. then there is the neutral wire. on a true 50 amp circuit the neutral only carries the imbalance. here if your two hot leads are one the same phase the entire current will have to go back down the neutral wire which may only be sized to carry 20 amps. and it is right at the marginal level whether a 20 amp supply will actually run an a/c. at full load it may supply around 2200 watts. many people say they run a/c's with the honda 2000 watt generators. some say they can't.

unless you absolutely know what you are doing and how the 20 amp circuits are supplied, i'd pass on it. the fact that you asked here tells me there is some doubt on your part.

babock · 06-08-2018, 01:17 PM

Quote:

Originally Posted by RV Randy

Yes on the 50a in the RV. As long as each 20a outlet is on a different leg, won't that give 40a total? That's the way a 50a outlet is wired.

Your AC is only on one of the legs. Yes your other leg will also have 20A. Each leg will have 20A of capacity of course you will have to know what loads are on each leg so you don't go over 20A per leg.

babock · 06-08-2018, 01:19 PM

Quote:

Originally Posted by CHICKDOE

unless you absolutely know what you are doing and how the 20 amp circuits are supplied, i'd pass on it. the fact that you asked here tells me there is some doubt on your part.

Totally agree!

Kaadk · 06-08-2018, 01:20 PM

If you separate the ACs from the coach, you could actually get up to 60a, provided you have enough ends to make enough plugs.

AC1: Plug 1
AC2: Plug 2
Coach (Converter, other 110 needs): Plug 3

Trying to combine and then split again, even if you have a 20 on each leg, you don't technically have a total of 40, you have a total of 2x20. Basically, if that one leg exceeds 20, it still trips, it doesn't borrow from the other leg.

mookieblaylock · 06-08-2018, 02:15 PM

Randy,

I realize this isn’t related to the question you asked, but I run my front A/C in the DX3 when plugged into a single 20A circuit at the house all the time. It flips over to the inverter briefly when starting up the compressor, but switches back to line in immediately afterwards. With it running, the fridge plugged in, and the charger limited, I only see it pulling about 12A. That’s with the batteries fully charged.

The front and rear duct is connected, so it provides some cool air to the rear of the coach as well. Might be an alternative to running the generator all day...

JT

RV Randy · 06-08-2018, 02:19 PM

That's what I did initially yesterday. I saw the AC in/Inverter lights flipping as you described. The AC unit ran (at least the fan) but it was much quieter and it seemed like the compressor would not stay on.

5picker · 06-08-2018, 02:28 PM

How many A/C units are you trying to run?
If just one, adapt the 50a shore service to 20a and problem solved. (providing you don't try to run much else)

Other than that, (or if you are trying to run two units) the safest way would be remove the romex feed wires at the rigs breaker box and temporarily install a male 120v plug. Run an extension cord to each feed. Unless you know absolutely sure the "multiple 20a 110 outlets" are on different phases, you run the risk of problems.

mookieblaylock · 06-08-2018, 02:28 PM

I don’t know if this does anything other than correct the usage gauges for accuracy, but I did switch my incoming service to 20A on the Plex panel. I think I limited the charging capacity on the Xantrex panel to 20A as well.

Again, not sure if that changed anything, but I had similar experience with the compressor not kicking on when these were set to 15A. Could have been coincidental.

mikew968 · 06-08-2018, 02:35 PM

My Honda 2000 will not run 1 a/c unit in my Seneca.

RV Randy · 06-08-2018, 04:13 PM

I have a pretty good idea of what I'm doing, but I always ask input and opinions from others who are experts.

I did plug the harness into the 2 outlets and measured.

L1 to G & N = 120v

L2 same

L1 to L2 = 240v

G to N = 0

That matches the 50a wiring schematic posted by WMTIRE. But the 110 outlets are both GFI and one or the other would pop the GFI unless you plugged both 110 plugs in at the same time. So, no live test until I do further research. I will just run the generator until it cools down in the evening, then I will switch to the 20a extension cord to run the fans and charger.

I did discover another DX3 at the track. It's brown with black/silver stripes. Will go meet them tonight when it cools off.

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