50 Amp to 30 Amp

Clydaho · 03-15-2021, 05:53 PM

I have a 2019 Bullet with 30 Amp hookup. If I use a 30 to 50 adapter when I hook up to a 50 amp hookup, is there any advantage? Will I have more Amps available to run the AC, TV, Microwave and coffee maker all at the same time? Or do I get 30 amps going into the trailer because that's what it is?

Any advice is appreciated.

**sourdough** · 03-15-2021, 06:00 PM

A 30A trailer is just that, a 50A dogbone does nothing but take the 50A outlet and cut it down to 30A. If you bought a 30A trailer....that is what it is and you are limited by that number. A 50A trailer actually has 100A of useable service, a 30A trailer is strictly 30A - a big difference.

Bill-2020 · 03-15-2021, 06:07 PM

A bonus here is that 50 amp outlets are typically used less and can have better (tighter) connections than the 30 amp outlet on the same pedestal. Creates a better connection and less prone to overheating the plug on a bad 30 outlet. I made a short dog bone for myself for this purpose. I usually use the 50 amp side and the dog bone for my 30 amp TT when the 30 amp plug/outlet connection is loose.

Clydaho · 03-15-2021, 06:10 PM

sourdough and Bill-2020,
Kind of what I thought, but needed to hear it from the more seasoned veterans like you.

Thanks a bunch!

Bill-2020 · 03-15-2021, 06:15 PM

Quote:

Originally Posted by Clydaho

sourdough and Bill-2020,
Kind of what I thought, but needed to hear it from the more seasoned veterans like you.

Thanks a bunch!

I'm not a seasoned veteran - I learned that trick from here! Keep reading around, you'll learn more than you thought you knew already.

BigBobIa · 03-15-2021, 06:28 PM

Question for the electricians.

A 30A is a single 120V leg with a 30A single breaker.

A 50A is two 120V legs (if true 220V then out of phase) on two breakers which are hooked together so if one overload trips, it kills the other. So my question is are the legs 25A x 2= 50A or 50A x 2= 100A?

If total 50A then using a 50 to 30 dog-bone would only give you 25A. If 100A total then you really have 50A going to your 30A house wiring.

Does this make sense?

Bill-2020 · 03-15-2021, 06:46 PM

Quote:

Originally Posted by BigBobIa

Question for the electricians.

A 30A is a single 120V leg with a 30A single breaker.

A 50A is two 120V legs (if true 220V then out of phase) on two breakers which are hooked together so if one overload trips, it kills the other. So my question is are the legs 25A x 2= 50A or 50A x 2= 100A?

If total 50A then using a 50 to 30 dog-bone would only give you 25A. If 100A total then you really have 50A going to your 30A house wiring.

Does this make sense?

I understand your statements. No electrician here either, but I understand it as the main breaker in the camper would limit the camper from pulling more than 30 amps, if 50 was available. (If the 25 amp theory applies, then yes it would be less amperage available, but I also understand what Danny states, the 50amp camper is really a 100 system with two 50 amp legs.)

**JRTJH** · 03-15-2021, 07:24 PM

Quote:

Originally Posted by BigBobIa

Question for the electricians.

A 30A is a single 120V leg with a 30A single breaker.

A 50A is two 120V legs (if true 220V then out of phase) on two breakers which are hooked together so if one overload trips, it kills the other. So my question is are the legs 25A x 2= 50A or 50A x 2= 100A?

If total 50A then using a 50 to 30 dog-bone would only give you 25A. If 100A total then you really have 50A going to your 30A house wiring.

Does this make sense?

Actually, it's 240 VAC (not 220 VAC)....

The RV "50 amp power" is two legs of 50 amps each. That's a total of 100 amps on the cord and available to the trailer. When "calculated" that means there are two legs, each having the potential to deliver 120x50=6000 watts of energy. That's a total of 12,000 watts of power. A RV "30 amp power" is one leg of power. That's 120x30=3600 watts of energy. Roughly 1/3 as much power when compared to the 50 amp RV system... In theory, the 30 amp RV system could never "blow the 50 amp pedestal breaker". Using that same theory, "IF" the trailer power cord were to short out, it would likely blow the pedestal power breaker, but in the event of any excess load (over 30 amps) the trailer main breaker would open, protecting the trailer, the shore power cord and the pedestal breaker from any load over 30 amps.

As for your comment about plugging a 30 amp cord into a 50 amp socket on the power pole. Consider that your house has a 200 amp system, protected by a 200 amp "main breaker". It is plugged into a "power line fed by a 2,000 amp transformer" hanging on the telephone pole down at the corner... So, by comparison, both systems, the 30 amp trailer plugged into a 50 amp source and your 200 amp house plugged into a 2000 amp source.... Both are protected by the "main breaker". The trailer by a 30 amp main and your house by a 200 amp main.

Within reason, it doesn't matter what the potential ampacity of the source is, the trailer can only draw "up to 30 amps" at which time, the 31st amp will open the main breaker and shut down power.

The "within reason" comes in when you have an electrical source so powerful that you can't get close enough to plug the trailer into it without it arcing to you, electrocuting you.... Systems that powerful can't be "used in a casual manner, but you won't find one in a campground.....

MarkEHansen · 03-16-2021, 12:04 PM

Note also that when you have a 30amp trailer plugged into a 30a service, your trailer is protected by both the trailer's 30A breaker and the pedestal's 30A breaker. If you instead plug into the 50A pedestal, you lose (mostly) that second line of defense. If your trailer attempts to pull more than 30A and your trailer's 30A breaker doesn't open (for some reason), the 50A service will quite happily supply you more current than your trailer wiring is able to support.

**JRTJH** · 03-16-2021, 12:45 PM

Quote:

Originally Posted by MarkEHansen

Note also that when you have a 30amp trailer plugged into a 30a service, your trailer is protected by both the trailer's 30A breaker and the pedestal's 30A breaker. If you instead plug into the 50A pedestal, you lose (mostly) that second line of defense. If your trailer attempts to pull more than 30A and your trailer's 30A breaker doesn't open (for some reason), the 50A service will quite happily supply you more current than your trailer wiring is able to support.

Yep, but that's exactly how your house is wired. You have a 200 amp "main breaker at the top of your house distribution panel". That is "hot wired to the "upright pipe on your roof" and that is hot wired to the 2000+ amp wiring that runs either from pole to pole or underground to the nearest utility company transformer that is protected by 750 amp (estimated) fuses. There's no "second line of defense" in your home and AFAIK, none required by any code.

If there's "no concern" for a $300K house full of memories and family members, why would there be more concern for a trailer's electrical system that's rated to carry 1/6th as much electrical load ???

MarkEHansen · 03-16-2021, 12:58 PM

I didn't say it was required, only that it's going away when opting to connect to the 50A service. Each consumer can decide how important (or not) that is for themselves.

dutchmensport · 03-16-2021, 02:20 PM

Very simple video about RV 30 amp vs 50 amp that will answer the OP's questions.

YouTube Video, click here.

**flybouy** · 03-16-2021, 02:59 PM

I use a 50 amp dogbone whenever possible. Typically the 30 amp recep. in the pedestal is worn out and the 50 is good and tight. As far as tripping, it's typicall the pedestal 30 amp breaker that trips because it's loose and causes heat. I've had them trip many times and the trailer breaker trip one time.

That's been my experience ovger many years.

Bill-2020 · 03-16-2021, 05:38 PM

Quote:

Originally Posted by flybouy

I use a 50 amp dogbone whenever possible. Typically the 30 amp recep. in the pedestal is worn out and the 50 is good and tight. As far as tripping, it's typicall the pedestal 30 amp breaker that trips because it's loose and causes heat. I've had them trip many times and the trailer breaker trip one time.

That's been my experience ovger many years.

Clydaho - This is who I got the idea from some time ago and made my own very short dogbone adapter. ^^^

Mark - Just this past weekend the girls took a weekend to themselves with the grandkids (all three of them!

). I took the camper to the CG on Thursday afternoon, hooked it all up, kissed the girls goodbye and went home for a quiet weekend with the pup. When I returned on Sunday to pick/them up, I learned that the 30 breaker on the pedestal had tripped on them mid-day on Saturday (hot day, all sites running A/C). The nice camper next to them helped DW reset that breaker. All good from then on. I didn't use the dogbone this time because the 30 amp outlet was in good condition and had a tight fit. Breakers are not made to be used like a switch, but they are at CGs and they get weak from it. (and it's times like that when I'm glad I use an EMS too!)

SummitPond · 03-17-2021, 12:35 PM

Quote:

Originally Posted by JRTJH

Actually, it's 240 VAC (not 220 VAC)....
<snip>

Back in the day we used to call it 110V/220V and in the intervening years it "became" 120V/240V.

I suspect it always was 120V per leg, so why the former reference to calling it 110V? Any ideas?

MarkEHansen · 03-17-2021, 12:40 PM

It used to be 110V, but was changed to 120V in 1984.

**JRTJH** · 03-17-2021, 01:14 PM

Quote:

Originally Posted by SummitPond

Back in the day we used to call it 110V/220V and in the intervening years it "became" 120V/240V.

I suspect it always was 120V per leg, so why the former reference to calling it 110V? Any ideas?

The exact quote to which I was responding is: "A 50A is two 120V legs (if true 220V then out of phase)"

If it's two legs of 120V then it's 240 total, not 220.

It becomes "significant" when you start determining wattage. 110 VAC@30 amps is 3300 watts. 120 VAC@30 amps is 3600 watts. That's a 300 watt difference.

In a 50 amp circuit, it's even more significant: 110VAC@50 amps is 5500 watts, 120VAC@50 amps is 6000 watts. In an RV 50 amp system, that's 1000 watts difference.

**flybouy** · 03-17-2021, 01:27 PM

https://www.google.com/url?sa=t&sour...g41K9Hgywf9JIY

BigBobIa · 03-17-2021, 02:19 PM

Quote:

Originally Posted by MarkEHansen

It used to be 110V, but was changed to 120V in 1984.

Proves I am officially old!

cavie · 03-17-2021, 04:18 PM

Quote:

Originally Posted by BigBobIa

Question for the electricians.

A 30A is a single 120V leg with a 30A single breaker.

A 50A is two 120V legs (if true 220V then out of phase) on two breakers which are hooked together so if one overload trips, it kills the other. So my question is are the legs 25A x 2= 50A or 50A x 2= 100A?

If total 50A then using a 50 to 30 dog-bone would only give you 25A. If 100A total then you really have 50A going to your 30A house wiring.

It is 2 legs 50 amps ea. 50 amps total.

Does this make sense?

Nope, makes no sense at all. RV 50 amp is 120/240 volts. two legs at 50 amps each. 180 degrees out of phase. It is called split phase. There is nothing 25 amps about it. if one leg goes over 50 amps both legs go dead. No Electrician in his life ever said 100 amps available.

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