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Old 11-03-2019, 09:45 AM   #1
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Can 20 amp and 30 amp be used simultaneously?

Please settle this for me. As if it's possible to settle anything on the Internet

If the post has separate 30 amp and 20 amp breakers can they both be used simultaneously?
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Old 11-03-2019, 09:57 AM   #2
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Yes. each circuit is suppose to have its own circuit breaker.

Someone actually makes an adapter with a 30 amp male plug and a 20 amp male plug and a 50 amp female plug
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Old 11-03-2019, 10:11 AM   #3
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Quote:
Originally Posted by LJowdy View Post
Yes. each circuit is suppose to have its own circuit breaker.

Someone actually makes an adapter with a 30 amp male plug and a 20 amp male plug and a 50 amp female plug
Well! I was just trying to settle an argument, but are you saying that if you only have a 30 and 20 on the post you could still run a 50 amp rig with that adapter?

It would seem so, but I'm not an electrician ... never even played one on TV.
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Old 11-03-2019, 10:25 AM   #4
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Quote:
Originally Posted by EdInArk View Post
Well! I was just trying to settle an argument, but are you saying that if you only have a 30 and 20 on the post you could still run a 50 amp rig with that adapter?

It would seem so, but I'm not an electrician ... never even played one on TV.
Not quite that simple;

- https://rvshare.com/blog/rv-electrical/
- https://www.rv-dreams.com/rv-electrical.html
- The 50-amp 120/240-volt 3 pole 4
- https://www.amazon.com/Camco-Heavy-P...9JSFCFV2M3BKE2
- https://www.rvtravel.com/more-power-...ur-rv-that-is/

If you read and understand all this they might let you play an Electrician on TV

Hope this helps,

ps - IMHO the answer to your original Question is 20+30 ='s 50 but with electricity and RV's the math is different - as 50 actually ='s 100 - New Math?
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Old 11-03-2019, 10:26 AM   #5
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Depends on several factors. Some rv's won't work on a GFI protected circuit. The 20 amp plug is always a GFI. My 5th wheel won't but my Motorhome will. In some campgrounds it is against policy to plug into both outlets. That is because they use common wiring to power both plugs with a maximum draw of 30 amps total. Also just to stir the pot for those that don't understand it I feel compelled to mention true "50 amp" rv service is 100 amps total @ 50 per leg so it really isn't gaining much. On a pedestal that isn't designed for that type of use the voltage drop will probably not allow you to use both a/c units anyway.
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Old 11-03-2019, 10:27 AM   #6
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That would totally be dependent on which phase the two plugs were attached to in the breaker box, a 50 amp requires one leg from each phase which is actually two 120 volt phases with a common neutral, if you take a voltage reading from the two large flat blades you will get 240 volts , each leg to neutral will yield 120 volts each. I have never seen an adapter to add a 30 a and a 20a together myself.
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Old 11-03-2019, 10:32 AM   #7
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Quote:
Originally Posted by EdInArk View Post
Well! I was just trying to settle an argument, but are you saying that if you only have a 30 and 20 on the post you could still run a 50 amp rig with that adapter?

It would seem so, but I'm not an electrician ... never even played one on TV.

If the post is wired according to the "standard," with a 240vac feed, the 30 amp CB should be powered by one line and the 20 amp CB, by the other. Using two adapters, you would be able to "combine" the feed into your 50amp RV but the amperage available to your RV would be limited to 30amps for anything on that line, and 20amps for anything on the other. You would not have full 50 amp service on each line as you would if connected to a 50 amp post connection.
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Old 11-03-2019, 11:54 AM   #8
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Can 30 amp and 20 amp be used simultaneously ? Yes, but check the campground rules - I have stayed at several public and private campgrounds that prohibit this in particular if they charge different nightly flat rate prices for camping with 20, 30, or 50 amp electric service.
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Old 11-03-2019, 12:00 PM   #9
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Originally Posted by spdracr39 View Post
Depends on several factors. Some rv's won't work on a GFI protected circuit. The 20 amp plug is always a GFI. My 5th wheel won't but my Motorhome will. In some campgrounds it is against policy to plug into both outlets. That is because they use common wiring to power both plugs with a maximum draw of 30 amps total. Also just to stir the pot for those that don't understand it I feel compelled to mention true "50 amp" rv service is 100 amps total @ 50 per leg so it really isn't gaining much. On a pedestal that isn't designed for that type of use the voltage drop will probably not allow you to use both a/c units anyway.
It's a matter of semantics, but it's a *50 ampere, 120/240VAC circuit*. That it is a split-phase service allows it to provide up to 50 amperes of current on each side of the split (and the split point is where "neutral" comes from in this service) but it's still a 50 ampere service. That sounds contradictory with the next paragraph, but it's not...



As for "isn't gaining much" I disagree because doubling the current is 100% MORE. Unless, of course, you consider double to be not much...
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Old 11-03-2019, 12:25 PM   #10
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They run a 120 volt, 50 amp line to a post.
At that post are 2 breakers, a 30 and a 20 amp. There is no second leg for 240 volts.

Yes you can use both, I am right now, so I can run 2 electric heaters in my 30 amp MH. Most are for electric grills and things like that.

ALL 50 AMP SERVICE IS 120/240 VOLTS. Read your power cord plug.

There is no 240 volt service avalable in a 30 amp post. Why would there be, it wasn't used back when they were installed.
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Old 11-03-2019, 01:16 PM   #11
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Some campgrounds are wired one way some another. Usually you can use both the 30 amp and 20 amp at the same time. However, You have no way of knowing what the campground branch breaker for your pedestal is. It may be 30 amp, it may be 50 amp. Wiring code usually allows either way.

Some RV's and TT's have simple 50 amp 240 volt main service entrance. They will work with a 30/20 split adapter. Both legs of the service will be live. It will not overload the neutral because it is still limited to 50 amps total.

One leg will trip the pedestal when loads exceed 20 amps, the other will trip the pedestal when you exceed 30 amp loads. If the campground branch for your pedestal is 30 amps, the campground branch breaker will trip when you exceed 30 amps total on the two legs.

The campground may not have a maintenance person working at the time and you may have to wait until the morning of the next business day for a maint. person to arrive and reset it.

Some Rv's and TT's have sophisticated transfer switches and battery management systems. Of course if your BMS can detect the 30 and activate both legs you do not need an adapter. However, some systems will freak out using the adapter.

A rare few 50 amp RV's and TT's have a 240 appliance and therefore a 240 volt circuit. It will most likely not work using the adapter.

By the way, The service entrance for a TT or RV is electrically the same as the service entrance for a home. The main difference is, most homes have a much larger amp capacity. Modern home service entrances are all 240 volt two leg systems, but theoretically they could be 120 volt 30 amp one leg systems like many TT's.
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Old 11-03-2019, 01:16 PM   #12
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Thanks for all the input. Nothing's ever easy is it

We are a 30 amp rig and during cold weather we use a couple of 1500 watt heaters on low -- 700 watts I think. I have two 15 amp breakers for 120 volt outlets, so i plug one into a jack on each one. Problem is that one of us will sometimes start the microwave without remembering to turn off that heater and trip a breaker. I know some folks run an extension cord out the window to that 20 amp jack.

Thanks
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Old 11-03-2019, 01:24 PM   #13
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I have read over the years on this and other forums that the term “it depends” is appropriate here. Some electrical posts say you can, some no as it depends on how they are wired. And then I have seen at some campgrounds clear and bold lettering that you MAY not use more than one at a time, and if by doing so you damage the system, you will both pay for the repairs and be asked to leave. So check with the CG before you either plug two or more cords into a single post or one of the combo cords.
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Old 11-03-2019, 01:38 PM   #14
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My campground is wired with a 50 amp main breakers feeding 30 amp peds.
The 50 amps are 240 volt feeds to the box. They are 60 amp 240 volt 6 circuit sub panels with no main breaker in them. In the box is a 30 amp single pole breaker and a 20 amp single breaker. 30 feeds a 30 amp RV outlet and the 20 feeds a 20 amp GFI outlet. So yes, there are indeed 240 volts L1 and L2 feeding the power box. The 30/20 adapter mentioned above does cause problems because as mentioned some RV's do not work when using the GFI circuit. I have tested this theory on my two trailers and neither wold work when plug into a GFI circuit.
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