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Old 06-13-2020, 10:11 PM   #21
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because the nomenclature for 'regular household outlets' is a 15amp circuit, and which uses the 3-prong male end that we are all accustomed to seeing.
Campgrounds, RV parks, and many 'outside' and garage outlets at homes are 20amp outlets, since they may power tools and such.
While 'technically' a dedicated 20amp outlet, with 12/2 wire cable, and a 20amp breaker, will have a 'special' 3-prong male outlet, with one of the slots turned horizontal, most who install 20amp breakers and 12/2 wiring aren't trying to limit the usage to only tools or appliances with this special plug, but to allow simply MORE amperage to be used.
The only real difference between a 'normal' 15amp outlet and a 20amp outlet is the wire size and the breaker size - the outlet is typically exactly the same.

When the factories design and build these adapters, they can't use the term '20amp', since that is 'technically' relegated to only 'special' outlets, so they default to 15amps, which we all know and love.

You'll find though, when you arrive at most any rv park or campground, that the outlet's breaker is shown as a 20amp size, which gives you the greater amperage usage, but with the same male prong plug end.

So, yes, 'technically' it's a 15amp adapter, but for practical purposes it's able to handle the 20amp outlet you will be plugging it into.
I get that, what I was trying to say is, maybe these adapters are using a 14 gage (15amps) wire vs a 12 gage (20amps) wire. And that is why they say 15amps vs 20amps because of the gage of wire they used.
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Old 06-13-2020, 10:13 PM   #22
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remember, though, that the gauge wire is less important, if that, since it is such a SHORT run, full encased by the rubber exterior, and chances are you are not going to be pulling the full 20amps, in most any case, at least not for long. I imagine the factories know this, but don't use the term 20amp because that would infer the 'special' male plug, which it does not have.
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Old 06-13-2020, 10:16 PM   #23
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and, interestingly enough, if you have two 13.5kw roof top a/c units, you CAN run both from just good 'ol regular 30amp RV service, no problem.

(having said that, there are many discussion here and on other forums of this 'disagreement', but many of us have done this quite often, in the hottest of months, when required - sure, you can't 'also' do everything else, like have the battery charger and electric water heater and microwave on at the same time, but with due diligence, it can work...)
I have read that people have wired in easy starts (I think that is what they are called) to their AC units. From what I read that it slowly kicks in the draw of an AC unit. As when it first turns on it draws itís max load.
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Old 06-13-2020, 10:20 PM   #24
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remember, though, that the gauge wire is less important, if that, since it is such a SHORT run, full encased by the rubber exterior, and chances are you are not going to be pulling the full 20amps, in most any case, at least not for long. I imagine the factories know this, but don't use the term 20amp because that would infer the 'special' male plug, which it does not have.
Gotcha, I get the short run as longer runs need to be calculated. Thanks for your thoughts and explanation on that.
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Old 06-13-2020, 10:23 PM   #25
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it works, yes, but only IF the smaller 15/20amp outlet is NOT a GFCI protected outlet...

I've done this many times, but generally the 15/20amp outlet is from another source, such as a nearby building, using an extension cord to reach it.

For some reason, the GFCI protected outlets, which are now common and normal in almost every campground and rv park, do not play well with these adapters, and they will not pass thru the power to the RV.

The reason is that the adapter shares the same common in the 50-Amp RV shore line (power cord) so the 30 Amp can go down one leg, and the 15/20 Amp can go down the other leg. However, when the (up to) 45~50 Amps returns combined down a single wire (the common), there’s no way to split the current “exactly” at the adapter between the 30A and 15/20A outlets so that the GFIC protected breaker doesn’t trip.

That’s all assuming that the 30A and 15/20A are all on same phase (an assumption made in posts above that’s not a given). In event that 30A and 15/20A are wired in pedestal to separate phases, the current imbalance coming back on the neutral will be even worse. Not that it makes a practical difference because the GFIC should trip either way when it senses an imbalance of a small fraction of one Amp.

Let me know if a numerical example would help clarify this.
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Old 06-13-2020, 10:24 PM   #26
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and here's an interesting 'video' of various methods and electrical concerns and adapters, etc... real life stuff

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Old 06-13-2020, 10:34 PM   #27
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The reason is that the adapter shares the same common in the 50-Amp RV shore line (power cord) so the 30 Amp can go down one leg, and the 15/20 Amp can go down the other leg. However, when the (up to) 45~50 Amps returns combined down a single wire (the common), thereís no way to split the current ďexactlyĒ at the adapter between the 30A and 15/20A outlets so that the GFIC protected breaker doesnít trip.

Thatís all assuming that the 30A and 15/20A are all on same phase (an assumption made in posts above thatís not a given). In event that 30A and 15/20A are wired in pedestal to separate phases, the current imbalance coming back on the neutral will be even worse. Not that it makes a practical difference because the GFIC should trip either way when it senses an imbalance of a small fraction of one Amp.

Let me know if a numerical example would help clarify this.
Why would they NOT be on the same phase on a 120 VAC only pedestal? If they had run 240 VAC to the pedestal they could have a 50 Amp plug.
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Old 06-13-2020, 10:36 PM   #28
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The reason is that the adapter shares the same common in the 50-Amp RV shore line (power cord) so the 30 Amp can go down one leg, and the 15/20 Amp can go down the other leg. However, when the (up to) 45~50 Amps returns combined down a single wire (the common), thereís no way to split the current ďexactlyĒ at the adapter between the 30A and 15/20A outlets so that the GFIC protected breaker doesnít trip.

Thatís all assuming that the 30A and 15/20A are all on same phase (an assumption made in posts above thatís not a given). In event that 30A and 15/20A are wired in pedestal to separate phases, the current imbalance coming back on the neutral will be even worse. Not that it makes a practical difference because the GFIC should trip either way when it senses an imbalance of a small fraction of one Amp.

Let me know if a numerical example would help clarify this.
What are the odds that the CG has a regular plug on a GFI breaker? As I know with homes that people are using GFI breakers in the panel vs at the receptacle.
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Old 06-13-2020, 10:39 PM   #29
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none
as they want the 'camper' to be able to reset it
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Old 06-13-2020, 10:43 PM   #30
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Why would they NOT be on the same phase on a 120 VAC only pedestal? If they had run 240 VAC to the pedestal they could have a 50 Amp plug.
Valid point, but also there's the possibility that several sites, all on the same Main breaker, are on opposing phases(hot leg 1, versus hot leg 2) from the 240v supply. Sites 1, 3, 5 are on the RED hot leg, and 2, 4, and 6 are on the other BLACK hot leg, more-or-less helping to 'balance' the load.

In reality, though, if the main breaker for the set of RV sites is a 200amp size, say, it would take over 200amps of usage between all the 1, 3, and 5 sites to trip the main breaker if none of the other sites were being utilized, but 30amps x 3 sites is only 90amps, so it's not really 'probable' that it's any potential problem.
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Old 06-13-2020, 11:30 PM   #31
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Why would it not work? If it is providing you the addition leg over the 30 amps. Iím not an electrician but I understand basic fundamentals.
There is much more to electricity than your basic knowledge of it. Especially when it comes to GFI circuits and shared neutrals. GFI for simplicity is a mini computer.
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Old 06-14-2020, 12:11 AM   #32
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When I said itís not a ďgivenĒ, it means it is not physically necessary and therefore we canít assume it so. It may have been cheaper to wire that way (even if it doesnít meet code ó Iím not sure on that ó people can take shortcuts to save money), but who cares why it could happen. The possibility is there. Assume nothing until confirmed. Regardless, it doesnít matter either way because once L1 and L2 current is combined coming out of 50-Amp motorhome into a single neutral, the adaptor can not split it so precisely that the GFI protected circuit will receive exactly the same current in and out, and will trip.

For what itís worth, Iíve stayed at one campground where even the 30-Amp service was GFI protected. That would further complicate matters using this adapter. That particular campground also had 50-A service so adapter wouldnít have been required in the first place.
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Old 06-14-2020, 03:11 AM   #33
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There is much more to electricity than your basic knowledge of it. Especially when it comes to GFI circuits and shared neutrals. GFI for simplicity is a mini computer.
I would agree, that is why I said I understand the basic fundamentals. Thanks.
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Old 06-14-2020, 05:18 AM   #34
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Why would they NOT be on the same phase on a 120 VAC only pedestal? If they had run 240 VAC to the pedestal they could have a 50 Amp plug.
My camp has 2 pole 30's running to the PEDs. 240 volts to the buss bars. L1 and L2. A single 30 feeds the 30 amp outlet and a single 20 amp feeds the 20 amp GFI outlet. That's 240 inside the panel. No main breaker because there is less than 6 breakers. All per NEC. Electricity is not a DIY subject.

If they ran 50 amps they would have had to run much larger wire. $$$$$$$
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Old 06-14-2020, 01:43 PM   #35
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Between you and "Turner"; I'm thoroughly convinced to always call in the experts!
Thanks so much for all of the GREAT info!
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Old 06-14-2020, 01:57 PM   #36
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My camp has 2 pole 30's running to the PEDs. 240 volts to the buss bars. L1 and L2. A single 30 feeds the 30 amp outlet and a single 20 amp feeds the 20 amp GFI outlet. That's 240 inside the panel. No main breaker because there is less than 6 breakers. All per NEC. Electricity is not a DIY subject.

If they ran 50 amps they would have had to run much larger wire. $$$$$$$
that certainly makes sense for a campground where the power pedestals are 30/20 setups... a double-pole 30amp 'main' breaker services each panel, and therefore only 10/3 wire cable is required, which is true: a LOT easier to deal with, and capable of handling this setup just fine.

Clarify what you mean by 'No main breaker', though. If there is a 30amp double-pole breaker set for EACH of these sites, in a Main Utility Panel on the property, I would guess, where then is the 'MAIN BREAKER' for all of these?
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Old 06-14-2020, 02:17 PM   #37
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that certainly makes sense for a campground where the power pedestals are 30/20 setups... a double-pole 30amp 'main' breaker services each panel, and therefore only 10/3 wire cable is required, which is true: a LOT easier to deal with, and capable of handling this setup just fine.

Clarify what you mean by 'No main breaker', though. If there is a 30amp double-pole breaker set for EACH of these sites, in a Main Utility Panel on the property, I would guess, where then is the 'MAIN BREAKER' for all of these?
Yes, main breaker at the distribution panel. No main at the ped. Just 1 30 and 1 20. However, because of the distance and voltage drop the wire size should be a minimum of 1/0 at least just to get 30 amps. It is not. It is # 4 ALM and therefore I must use an autoformer on a 3 year old system. 116 volts with no load just don't cut it!
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Old 06-14-2020, 02:25 PM   #38
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I see... well, that's pretty common at any campground or rv park pedestal - no 'Main' breaker at the pedestal since each circuit already has it's own breaker - a 30amp and 20amp, in your scenario.
The 'Main' breakers are at the campground's own Utility 'Main Panel', of which sometimes there are several, or many, depending on the size of the campground, number of sites, etc.

I don't see where, though, 116volts is any issue - seems like that's actually more 'normal' than not, most anywhere.
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Old 06-14-2020, 03:30 PM   #39
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I see... well, that's pretty common at any campground or rv park pedestal - no 'Main' breaker at the pedestal since each circuit already has it's own breaker - a 30amp and 20amp, in your scenario.
The 'Main' breakers are at the campground's own Utility 'Main Panel', of which sometimes there are several, or many, depending on the size of the campground, number of sites, etc.

I don't see where, though, 116volts is any issue - seems like that's actually more 'normal' than not, most anywhere.
127 is considered the normal delivery all over the US. 110 died with your grand dad. These days it is commonly know and 120/240.The problem with my 116, because of the undersized wire, quickly becomes 108 volts with the coffee pot. add the toaster and.......see where i'm going?
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Old 06-14-2020, 03:45 PM   #40
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Yeah, middle of summer, A/Cs running all out, even lower voltage, higher current, followed by loss of power; leading to unhappy campers.
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