Can I run what I need on 30amps

[5picker]

Originally Posted by wmtire

What! It's the 15/20 amp GFCI outlet on the pedestal that is the problem and trips, with the shared neutral to the 30 amp outlet via the cheater adapter.

I believe cavie was suggesting to put the R/V's GFCI curcuit on the 30a leg that feeds into the camper and eliminating any GFCI in the R/V on the 15/20a feed that connects to the pedestal GFCI. Then there would be no interaction.

Yes, you'd have to do a little wire swapping in the power distribution/breaker box in the R/V but I'd bet it would work.

[wmtire]

Originally Posted by 5picker

I believe cavie was suggesting to put the R/V's GFCI curcuit on the 30a leg that feeds into the camper and eliminating any GFCI in the R/V on the 15/20a feed that connects to the pedestal GFCI. Then there would be no interaction.

Yes, you'd have to do a little wire swapping in the power distribution/breaker box in the R/V but I'd bet it would work.

I was editing my post as you were posting. This should not have anything to do with the pedestal GFCI. Please see my edits.

Remember that a GFCI trips due to a very small amperage difference in the hot leg and neutral return line. The shared neutral over on the 30 amp leg, should make the neutral on the 15/20 amp leg mismatch to it's hot leg...thus tripping the pedestal gfci as designed....as I understand it

[cavie]

Originally Posted by wmtire

I was editing my post as you were posting. This should not have anything to do with the pedestal GFCI. Please see my edits.

Remember that a GFCI trips due to a very small amperage difference in the hot leg and neutral return line. The shared neutral over on the 30 amp leg, should make the neutral on the 15/20 amp leg mismatch to it's hot leg...thus tripping the pedestal gfci as designed....as I understand it

A GFI measures only the difference of the power being run thru the breaker/outlet neutral and ground. The 30 amp leg (A) will not be GFI protected until you get to the GFI in the MH. Then that one circuit will be protected.

Everything on the 20 amp leg (B) will be protected by the 20 amp GFI at the pole. It senses the power going thru it with the neutral going thru it. If there is no neutral to ground leak there will be no trip. Phase A neutral and power is not going thru it.

1/2 the panel will be GFI protected and 1/2 will not be GFI protected except the GFI circuit of the A phase.


Think of it as using 2 single pole breakers as a 240 main with no handle tie. only one side will trip. leaving one phase hot.


The GFI only worries what is going on with the neutrals of the circuits with the power going thru it.
2 GFI's in series are gonna fight over who is in control. That's what happens in the real world, not on paper. I don't know why and don't care. If they give me too much trouble I remove it and get on with my life. Just on my stuff.

PS. GFI's are like a "Black Tank Flush". How did we get by?

[wmtire]

Originally Posted by cavie

A GFI measures only the difference of the power being run thru the breaker/outlet neutral and ground.

Cavie, that is not how a GFCI works. A GFCI is looking for leakage current (aka imbalance) between the hot leg and neutral. There should be no discernable power to the ground unless there is a problem. Technically, you don't even need to have a safety ground connected to a gfci for it to operate. Mike Sokol explains it in the first link below, as well as the other two following his.

http://noshockzone.org/rv-electrical...oubleshooting/


https://www.ecmweb.com/basics/how-gfcis-work


https://safeelectricity.org/ground-f...rupters-gfcis/


Also I don't think you are understanding the split phase 120/240 volt 50 amp RV distribution yet again....and how it shares a common neutral. Please reread this link again. It's the common neutral which will show an imbalance on the 15/20 amp pedestal GFCI causing it to trip with the cheater adapter. The hot line amperage leaving the pedestals 15/20 amp gfci outlet will not have the same current/amperage coming back via the neutral to this outlet due to the shared neutral to the 30 amp outlet (which the shared neutral only carries the current imbalance between L1 and L2).



Electrical Tutorial - Chapter 3 - 30 Amp versus 50 Amp

[KyDan]

Originally Posted by cavie

A GFI measures only the difference of the power being run thru the breaker/outlet neutral and ground.

WRONG- please just google how does a gfci work.


From Wikipedia-- The GFCI device uses a differential transformer to compare the current "going out" on the hot leg with the current "coming back in" on the neutral.

The "how stuff works" website had a similar explanation.

[Mr. October]

Originally Posted by formerFR

this comes up from time to time, and they'll always be 'sides' to the argument, but YES, you can run two air conditioners on full 30amp shore power... that's not really debatable.

But, the confusion comes in when you try to run two at the same time along WITH OTHER 120v ITEMS... it's simply a mathematical equation: if all of your 120v items that are ON and RUNNING don't exceed 30amps, then you'll see no difference - it's only when you EXCEED the 30amps that you will trip the Shore Power breaker.
You could also trip an internal breaker, but since your air conditioners are certainly on different breakers of their own, that's unlikely.

What I've found, from experience, is not to 'assume' anything, but put it to the test. Yes, many will proclaim that running two air conditioners on 30amp Shore Power is impractical, but if the question is simply 'Can You?', then, YES, you can. Reality, though, is that many will also be trying to run other 120v items at the same time, therefore tripping a breaker.

Now, tripping a breaker is not a SIN, will not HURT your RV, and is in no way some type of 'no no' when you are camping, it's just a protection so that your internal RV wiring does not heat up past it's designed limits, causing a fire hazard. Your home is exactly the same way. If you use 'too many' things at the same time, or otherwise 'overload' a circuit, then the circuit's breaker trips. Not a biggy.


I say this: try it.

And here's a hint: first, turn off everything in your RV that runs on shore power or the generator, every 120v device such as the Electric Water Heater, computer or phone chargers, TVs....everything. THEN, turn on one air conditioner. When you hear it's compressor kick on, and cold air start, then turn ON the other air conditioner. You'll probably have no issues.
Start next to add the other items, such as TVs, satellite receivers, 120v fans, etc.

If you continue with no issues, you'll have learned that 30amp service can satisfy many just as 50amp service does, if you manage your usage and expectations accordingly.
No, using the microwave, a hair dryer, or turning on the Electric water heater while both air conditioners are running will probably cause you to suddenly trip a breaker, but you'll start to learn your limits.


ALSO, a big concern sometimes is whether the campgrounds Shore Power 30amp breaker is actually up to the task for a full 30amps of service. We've run into many situations, in hot weather especially, where the breaker was tripping prematurely. These breakers can grow 'weak' over time, tripping before the full 30amps is provided.
This is really a simple solution for the campground: change out the breaker with a new one.

I'm picturing the bit in the movie Apollo 13 where they are trying to power on the necessary systems without much power.

Also, I agree completely with the campground breakers not necessarily being up to snuff. The breakers aren't really designed to be used how campgrounds use them with getting regularly switched off and on to plug/unplug. They weaken quickly. More than once we've been grateful for a Friday evening maintenance person who can come around and swap them for us.

[cavie]

Originally Posted by KyDan

WRONG- please just google how does a gfci work.


From Wikipedia-- The GFCI device uses a differential transformer to compare the current "going out" on the hot leg with the current "coming back in" on the neutral.

The "how stuff works" website had a similar explanation.

That's exactly what I said and what you quoted I said. You keep reading about how the work and I'll keep install and replacing them as I have since the '80's. I'm just dying to see what happens when they start putting Arc Fault Breakers in RV's.

[Stormvet1st]

Originally Posted by popeye305

I traded in my 5er for 2012 motorhome. I already had a spot in Florida reserved for my 5er which was a 30amp spot. I called to upgrade to a 50amp spot and naturally they have no more available. The motorhome has 2 air conditioners instead of 1 am I going to have a problem with only 30amps? I was happy with my 5er but wife wants to travel more and I felt a motorhome was better then having to buy a new truck since mine has 110000 on it.

Your biggest issue including florida will be heat, maybe maybe not on the AC but heat will definitely start blowing breakers.

[gforgot]

Mr. Dan is correct. I had a new adapter, just purchased from CW. Only powered 1 leg, was faulty. fortunately, that was one of the few things they took back without a hassle. Watch what loads you use, you will be ok.

[TexasGuru]

Ditto on adapter comments above that all appliances will have power. We were camping with 30amps in our 5th wheel with 2 15k a/c units which tripped power pole breaker. We ran kitchen one during day and bedroom one at night and with frig, microwave, etc. with no problem.

[2manytoyz]

My previous Class A was a 1999 Bounder 36S. It was a 30A coach from the factory.



It had a built-in power management system:



It had dual 13,500 BTU Coleman A/C units, microwave oven, water heater element, washer/dryer, etc.

It ran BOTH A/C units almost non-stop for over a year to deal with the FL heat. The power management system would start the fans on both, kick the first compressor on, wait, then the second. If I applied another heavy load, like the microwave, the compressor on the second A/C would "shed", turning it off until the high load device was turned off.

If an even higher load was applied, the main A/C would be "shed" also.

So for those who think you can't have two A/C units with only 30A, that's not necessarily true. If you have two 15,000 BTU units, sure. The Dometic 13,500 BTU A/C unit on my 2007 TT only draws 10.5A running. The In-Rush current spike is 50A, but is quick enough not to trip a breaker.





I've not measured the current demand of our latest motorhome, mainly due to it having a 5500W onboard generator. I used a 2400W Yamaha generator with the TT.

Without an automatic power management feature, you would manually need to shut items down to stay under the 30A limit if you have dual A/C units, or you'll make the walk of shame to the power post to reset the breaker.

[formerFR]

well said : )

[fella10]

Originally Posted by popeye305

I traded in my 5er for 2012 motorhome. I already had a spot in Florida reserved for my 5er which was a 30amp spot. I called to upgrade to a 50amp spot and naturally they have no more available. The motorhome has 2 air conditioners instead of 1 am I going to have a problem with only 30amps? I was happy with my 5er but wife wants to travel more and I felt a motorhome was better then having to buy a new truck since mine has 110000 on it.

Did the OP(popeye305) ever come back to this thread? I've looked at all the pages and can't find that he did. .... did he ever use anyone's advice? .... If you're out there and still interested, and have a 20a outlet on the power pole ... with a simple wiring modification, you can run a regular 12/3 extension cord off that 20a outlet to run one of the ac's, ... I did that a couple of yrs ago to take the ac amp draw off our 30a circuit, it worked/works great, ... Since then I've gone beyond that and now using a 30a to two 15a adapter(if 50a is available to plug into), if desired I can run two extension cords, ... and once you bring that extra power into the rv, there's any number of ways it can be used, ... ac in summer, heaters in the winter, water heater, ect, ... so I guess that's turning our 30a system into a 45a or even a 60a system, ... anyway, I won't go any further unless you're interested, ... you may have already solved your problem, ...

[CTGREG]

Get soft starters for the acs. Reduces the amperage needed to start acs

[CTGREG]

Originally Posted by CTGREG

Get soft starters for the acs. Reduces the amperage needed to start acs

Google Macro Air soft starters. Best thing I did

[cavie]

Originally Posted by MR.M

you'll only be able to use 1 ac , most likely the main one , the other won't even power up . 50 amp has 2 legs in the electric panel , since your going 30 only one leg will be powered and the other one dead and what ever is tied to it . at least that's my understanding been wrong before

The 30/50 adaptor will take the one hot leg and apply it to both the 50 amp legs. Both legs will be hot! You will be able to use any combination of electric items you wish as long as the combined total of amp draw does not go over 30 amps. Just use one A/C at a time depending on where you are located in the MH. put the WH on gas. You'll be good to go.

[wmtire]

Originally Posted by cavie

The 30/50 adaptor will take the one hot leg and apply it to both the 50 amp legs. Both legs will be hot! You will be able to use any combination of electric items you wish as long as the combined total of amp draw does not go over 30 amps. Just use one A/C at a time depending on where you are located in the MH. put the WH on gas. You'll be good to go.

Not really following why you are quoting a post from 5 months ago that the member already acknowledged in post #11.

[Dodge Guy]

You’ll be fine running one AC at a time. Just run the front one during the day and the rear one at night.
30-50A adapter will power both legs in the RV so all Circuits are operational. To be safe pick up a Kill-a-Watt. Plug it into an outlet and it will show how many Volts you are working with.