Connecting 50 amp Classic to house service

[Klondike]

Suggest use only 1 adapter - 50A to 20A

[dasams]

Originally Posted by mikeinca

If I understood him correctly, his explanation was that power would be bridged on the other side of the converter, so it didn't matter if only one side of the 50amp circuit was hot.

As a new owner of a 50 amp AS, I've been trying to understand the wiring and my two AC's. I even started a thread about it. See http://www.airforums.com/forums/f37/...cs-172273.html

When I plugged into the 50 amp service where we are staying, I also attached my EMS-PT50X so that I could monitor the current. With the zone 1 AC running, there were ~20 amps on L-1 and ~3 amps on L-2. The second reading was interesting as I had read that the zone 2 AC was the only thing powered from L-2. Apparently not as the zone 2 AC was off but L-2 was pulling some amps. And I realize that AS has changed the wiring over the years.

I have the same Camco dogbone mentioned above and I'd like to do an experiment. If I have some downtime tomorrow, I'll switch to 30 amp service and put the EMS between the dogbone and the 50 amp cable to see which legs are hot. Any other ideas for a test run?

Thanks, Dave

[james.mileur]

The converter does not bridge the AC, and is powered from a single 20 amp breaker, 8 on mine , and does supply the entire DC distribution. That may be the L2 load.

[uncle_bob]

Originally Posted by james.mileur

The converter does not bridge the AC, and is powered from a single 20 amp breaker, 8 on mine , and does supply the entire DC distribution. That may be the L2 load.

Hi

.... so, if the Camco converter only powered up L1 and not L2, you would have no converter.....You also might not have the microwave if it also was on the other leg.

Bob

[dasams]

Well I conducted my little test using the Camco 55185 dogbone referenced in post #32 above.

I plugged the dogbone into the 30 amp pedestal and then plugged in my EMS-PT50X and then the 50 amp cable. See the picture below.

Here are the test numbers and no I didn't try to run both AC's while on 30 amp service.

1. No AC: L1 = 12 amp, L2 = 5 amp
2. Zone 1 AC: L1 = 18 amp, L2 = 3 amp
3. Zone 2 AC: L1 = 15 amp, L2 = 15 amp.

I think this makes it pretty clear that the dogbone provides power to both legs of the 50 amp cable and that you can run either of the AC's.

If I had a do over, I would have turned off the elec water heater as I think it was pulling power through L-1 during the first and third tests. This is just a guess but I can't think of anything else to explain currents. Thoughts?

[Mollysdad]

I see no problem with a 30 amp/50 amp adapter being wired so both legs of the 50 amp are connected. Because you never use 240v. there is no conflict with phase. As long as you remember that you still only have 30 amps available.
30 amp has a positive, neutral, and ground so the positive goes to BOTH + spades of the 50 amp, then the neutrals are connected and so are the grounds.

[alantbird]

I plug my 41 foot diesel pusher into a 110 outlet at two of our homes and can run one a/c plus the charger inverter. its all trial and error and common sense. In AZ I installed the 50 amp plug since we use it as a guest cottage and need to run both a/c in the summer.

[Mollysdad]

Originally Posted by dasams

I plugged the dogbone into the 30 amp pedestal and then plugged in my EMS-PT50X and then the 50 amp cable. See the picture below.

Thoughts?

I'm curious, did the EMS-50 show any odd readings? Since both legs were the same phase?

Your EMS 50 is chained to your ladder? But not the pedestal?

[james.mileur]

I used the same 30 - 50 dog bone and EMS 50 for a couple months with no issues.

from my antique Note3 - James

[mikeinca]

Originally Posted by dasams

Well I conducted my little test using the Camco 55185 dogbone referenced in post #32 above.

I plugged the dogbone into the 30 amp pedestal and then plugged in my EMS-PT50X and then the 50 amp cable. See the picture below.

Here are the test numbers and no I didn't try to run both AC's while on 30 amp service.

1. No AC: L1 = 12 amp, L2 = 5 amp
2. Zone 1 AC: L1 = 18 amp, L2 = 3 amp
3. Zone 2 AC: L1 = 15 amp, L2 = 15 amp.

I think this makes it pretty clear that the dogbone provides power to both legs of the 50 amp cable and that you can run either of the AC's.

If I had a do over, I would have turned off the elec water heater as I think it was pulling power through L-1 during the first and third tests. This is just a guess but I can't think of anything else to explain currents. Thoughts?

Dave, my only thought is that perhaps you could send your results to Rich at Camco and get him squared away on this!

Seriously, thanks for resolving my questions about the adaptor.

[dasams]

Originally Posted by Mollysdad

I'm curious, did the EMS-50 show any odd readings? Since both legs were the same phase?

No odd readings or any other issues.

Originally Posted by Mollysdad

Your EMS 50 is chained to your ladder? But not the pedestal?

Ha Ha! Good one! It's now wrapped around the pedestal but the smallest of bolt cutters will be able to liberate it. More importantly for security, I've covered the readout with blue tape so that it's a bit more stealthy at night. Those red LED's shout "here I am, take me away".

[uncle_bob]

Hi

For what ever reason, the EMS boxes do not look at the L1 / L2 for the presence of 240V. I'm not wild about that since on a 50A circuit it can be a problem. I understand the issue of it tripping out on a 30A adapter and why they did it that way.

The current meter functions on an EMS are fairly simple in terms of accuracy. Is it 15A or 16A? is not the sort of question they are designed to answer. If you start to work out what's what by turning things on and off, this may fake you out a bit. You will turn on a minor load and it will not report with enough accuracy for you to see what happened. A proper current meter is a much better way to get into minor details. They are fine for looking at big loads and spotting open wires.

Bob

[james.mileur]

Uncle bob, I called my EMS company to verify what they advertised as "accidental 240v". They verified it senses if the ground is missing and/or if the outlet is wired as 240 vice 2 single 120v legs.

Found this great summary for everyone that is still unclear.

http://www.rv-dreams.com/rv-electrical.html

[james.mileur]

What I use.
EMSPT50C Surge Protector https://www.amazon.com/dp/B004AQR53K..._GYNVzb6RMR24J

[Mollysdad]

Originally Posted by james.mileur

I called my EMS company to verify what they advertised as "accidental 240v". They verified it senses .. if the outlet is wired as 240 vice 2 single 120v legs.

Sorry for beating a dead horse, but there is no difference in wiring an OUTLET in 240 or 2(120). The trailer's wiring determines the 2 (120).

[uncle_bob]

Hi

Ok, back to the basics of the 50A connector.

1) You have a ground lead that should have no current on it in normal circumstances.

2) You have a neutral wire that is rated for 50A. Both the wire and the connector have this rating.

3) You have two hot leads each rated at 50A. Again both wire and connector have this rating.

If you had a DC circuit and put 50A into each of the hot leads, it all goes back out the neutral. That gives you 100A on a 50A wire. There are never fuses or breakers in a neutral. The problem would go un-detected. The wire (or connector) heats up and insulation melts. Next comes sparks and flames.

If you set up the two hot leads in phase, the neutral works just like a DC circuit. You overload the thing and bad stuff happens.

Fortunately it's AC and you have another option. You can change the phase of one of the hot leads. If the two currents are 180 degrees out of phase they cancel out. You get zero current down the neutral. Full load on one side and zero load on the other gives 50A down the neutral. That's ok, it's rated for 50A. When the two hots are 180 degrees out of phase a voltmeter will read 240V between them.

The AS its self could care less about in phase or out of phase once you get to the breaker panel in the trailer. Up to the panel, (inside and outside) it cares very much about phase if you are running > 50A into the trailer.

At least on my EMSTP50C, it's quite happy plugged into a 30A circuit through a normal dog bone adapter. In that case everything is in phase. It's also well below 50A, so no problem. I'd love to see some sort of LED flashing if it's in phase. I don't need it to disconnect. Just give me a sign all is not right ....

Lots of fun !!

Bob

[switz]

Airstream was usually able to wire the two A/C units to have one on each hot leg. Not mentioned above is that the factory inverter will be drawing power most of the time to keep the battery bank charged and or run the 12Vdc lights, refrigerator logic board, furnace logic board and water heater logic board plus all the other passive parasite 12Vdc loads.

So one needs to do a little testing to determine which leg has the water heater, the microwave and the power outlets. If both A/C units are running and the the wife wants to run a hair dryer (typically 1,800 watts or 15 amps), then knowing which additional appliance needs to be secured will prevent tripping the breakers.

[OTRA15]

Originally Posted by switz

. . .
Not mentioned above is that the factory inverter will be drawing power most of the time . . .
. . .

Don't you mean converter?

[mikeinca]

Key learnings (for me at least) from this thread so far:

The Camco 55185 30A/M < 50A/F dogbone will work in combination with a 30A/F < 15A/M dogbone to get power from an AC outlet as well as allow access to 30A power at an RV park without 50A service. It also seems that I should acquire a surge protector for 50A service and the Progressive Industries units seem like a popular choice; the EMS-PT50X being the latest version from what I've read.

Also, there is a single 50A < 15A adaptor that plugs directly into the trailer which will allow a normal heavy duty extension cord to provide power without having to use the 50A monster supply cable. This seems like an attractive option.

So one more question. If I use the 50A < 15A adaptor/extension cord setup to plug in to the 20A duplex circuit at my house, is a surge protector still required/desirable? If so, given the lower current involved could a regular 15A strip type surge protector be used? That would seem to be preferable to using the EMS-PTX50, presumably with multiple adaptors again involved.

[james.mileur]

Originally Posted by Mollysdad

Sorry for beating a dead horse, but there is no difference in wiring an OUTLET in 240 or 2(120). The trailer's wiring determines the 2 (120).

Well, fwiw, the old 3 wire 240 outlets for dryers/ovens that didn't have a neutral and with some electricians (I'm sure not uncle bob) who used the white lead and a piece of black tape for the second (white) hot lead from the second 120v breaker, results in a situation that could give a diy rv'r 240 to his new 30 rv outlet if, black tape was gone, he didn't understand how 240 comes through two leads (white & black), and didn't voltage check his new outlet, hooked up white to white, black to black, ground to ground, and no EMS in line.

Ka-pow, fizzle, puff of smoke, stink, buy all new converter, appliances, etc.

Or the trailer burns up in the driveway.

So, no dead horse, just burnt trailer 120v system. [emoji6]