No AC unless 30 amps

[beaubeau]

Posting for a friend ...
She has a new Jayco Melbourne. It’s on a Sprinter chassis.
Her AC works fine if she’s plugged into a 30 amp circuit (her RV doesn’t have a 50 amp plug).
But plugged into 20 amp it will run for a few minutes only.
So her husband bought a splitter from camping world meant to plug into to 2 110 outlets and combine them into 30 amps.
Same problem.
Any ideas?
This is what the splitter looks like in use

[SailingOn]

Our View (30 amps, Sprinter chassis) air conditioner will run indefinitely plugged into a 20 amp circuit via a DOGBONE adapter and a 25 foot 12 guage extension cord, so long as nothing else is drawing power. Yours should too.
Agree with KSG5000; corroded connections? something else drawing power?

[valhalla360]

Get rid of all the adapters and then start checking voltage.

[toedtoes]

Check the circuit breaker that the outlet is connected to. Is it a 20amp or a 15amp? Is there anything else connected to that breaker? Other outlets, appliances, etc.

I agree with above to use a quality 30 amp extension cord with a 30-15amp dogbone adapter at the outlet end. If nothing else is connected to the breaker and she is ONLY using the AC (no other appliances in the RV), or just the microwave or just the coffee maker, then she should be OK. If she wants to use two or more at the same time, then she will need to install a dedicated 30amp breaker and pedestal and hook into that.

[beaubeau]

This is all such good stuff. I've had to leave her house now, but look forward to getting back up there to try more troubleshooting!
Thanks so much!

[Ed_Gee]

Those cheater cords are designed to feed two hot legs of a 50A RV circuit. Often they will work for a 50A RV. However they cannot work on a 30A RV because the required 50A to 30A adapter only connects ONE. of the 50A legs to the 30A side. .....the other 50A leg is not connected.....for safety reasons as just mentioned in the previous post by naturist.

[CA_Traveler]

naturist wrote:
As mentioned, that splitter will do nothing in this application because it doesn’t combine the two 20 amp circuits. And it would be a death dealing device if it did because the odds are about 50/50 that any two randomly chosen and properly wired 120 volt outlets would be on opposite legs of a given240 volt service. This would result in an instant short circuit when plugged in, with attendant sparks and fire hazard. If one of the 120 volt 20 amp outlets was wired backward, you’d throw 240 volts on the camper instead, with equally devastating results.

The 2 neutrals in the adapter are shorted together and the adapter works OK with it's 2 hots on either opposite legs or the same leg.

If by wired backwards you mean reverse polarity then when plugged in one hot would be shorted to neutral and it's CB with trip. The 50A plug on the cheater cord would then have 120V on one of it's hot legs and 0V on the other.

[Ed_Gee]

naturist wrote:
As mentioned, that splitter will do nothing in this application because it doesn’t combine the two 20 amp circuits. And it would be a death dealing device if it did because the odds are about 50/50 that any two randomly chosen and properly wired 120 volt outlets would be on opposite legs of a given240 volt service. This would result in an instant short circuit when plugged in, with attendant sparks and fire hazard. If one of the 120 volt 20 amp outlets was wired backward, you’d throw 240 volts on the camper instead, with equally devastating results.

Ah ha! Someone who actually understands the ramifications!

[ksg5000]

I would ignore the splitter and focus on whether the problem is with your rig or the shore power. Since it works on 30 amp but not 20 amp maybe it's a loose connection, corrosion, problem with your power supply or similar issue which create higher resistance. Check the obvious - clean + tighten connectors - look for signs of burning - make sure you have turned off high demand things like electric water heaters etc.

[naturist]

As mentioned, that splitter will do nothing in this application because it doesn’t combine the two 20 amp circuits. And it would be a death dealing device if it did because the odds are about 50/50 that any two randomly chosen and properly wired 120 volt outlets would be on opposite legs of a given240 volt service. This would result in an instant short circuit when plugged in, with attendant sparks and fire hazard. If one of the 120 volt 20 amp outlets was wired backward, you’d throw 240 volts on the camper instead, with equally devastating results.

[CA_Traveler]

50A is not a misnomer except to most RVers. The standard uses the highest voltage and 50A refers to 240V and 50A * 240V = 12,000 watts. The complete spec is 120/240V, 3 pole, 4 wire, 60Hz and it's single phase. It's just like your home oven which uses 240V for heating and 120V for lights and clock. But very few RVs have 240V appliances so they use only the 2 120V hot legs.

[CA_Traveler]

IB853347201 wrote:
I have one of those splitters too. I have tried it several times in many different RV parks. It has not performed as advertised yet. In other words, doesn't work, its a gimmick!

Nope it works. However one problem is that if one of the outlets is a GFCI it will immediately trip.

There are other issues/concerns and CG owners are justified in banning it's use.

[beaubeau]

Thanks everyone this is all great info!
Lots to think about.
The first thing I tried was simply to plug her 30amp supply cord into a single 20amp outlet using just her RV cord and a 30->20 puck.
Same problem. AC runs a while then stops.
Sometimes it trips the 20amp breaker and sometimes the AC stops (but the microwave still has power (the keypad is lit) - in that case a long rest and restart everything and it will run a short while again before failing.

[IB853347201]

I have one of those splitters too. I have tried it several times in many different RV parks. It has not performed as advertised yet. In other words, doesn't work, its a gimmick!

[j-d]

In other words, all that adapting accomplishes nothing.
To put it another way, this isn't how electricity works.
Or... Take it Back and get a good 30A RV extension cord plus a good dogbone adapter to allow connecting 30A to a 20A receptacle. Then, minimize the electrical load in the RV. 20 should run the A/C along with the Converter and interior lighting. Won't allow microwave, coffee maker, electric water heater etc. That calls for 30A, no adapters, good connections. Even then, we have to "load shed" in summer with our 15000 A/C or winter with electric heaters. If one major load (like a toaster) goes ON, another, like Mr. Coffee, has to go OFF.

To add to Isaac's following along comment: 50A is a misnomer and 30A isn't. First the 30: One 30A hot times 120V is 3600 WATTS. Sounds like a lot but really not much to work with. Now the 50: One 50A hot times 120V is 6000 Watts and that's a big improvement over 3600 but there are TWO Hots giving 12000 WATTS to a 50A coach! That's what makes 50A Such a Big Deal! Nearly Four Times the Power over 30