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Pls explain 30amp vs 50amp wiring and breaker

luberhill
Explorer
Explorer
Ok so is this correct;
say my RV has a 30amp service and I want to wire an outlet in my pole barn. I just use a STANDARD 30amp single pole 110 breaker and run 10 gage romex to the outlet ?

Now lets say I have a 50amp service, I assume I can run that on the 30 amp service but only one side of the line on the RV will be hot ?

Now lets say I want to run a 50amp outlet ....I assume I have to use a 220 50 amp double pole breaker so that it feeds power to both sides ?

And would I need 8gage wire ?
2013 Winnebago Sunstar 26HE
21 REPLIES 21

CA_Traveler
Explorer III
Explorer III
ivbinconned wrote:
This thread has certainly helped me understand my present project better. Just started a thread above about installing a transfer switch so I can switch from shore power to 2000 gen that I can secure down in front storage compartment.

In looking at connections in transfer switch it is not clear to me what connects where?
All grounds are bonded. Neutral and hot (2 for 50A) are switched, hence inputs for gen and shore and outputs. Wire per the manual.

Portable gens may have other restrictions like floating neutral that need to be considered.
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Bob

Bumpyroad
Explorer
Explorer
ivbinconned wrote:
This thread has certainly helped me understand my present project better. Just started a thread above about installing a transfer switch so I can switch from shore power to 2000 gen that I can secure down in front storage compartment.

In looking at connections in transfer switch it is not clear to me what connects where?


just be sure that front storage compartment is properly ventilated.
bumpy

ivbinconned
Explorer II
Explorer II
This thread has certainly helped me understand my present project better. Just started a thread above about installing a transfer switch so I can switch from shore power to 2000 gen that I can secure down in front storage compartment.

In looking at connections in transfer switch it is not clear to me what connects where?
Ram and 34 ft Cedar Creek

wa8yxm
Explorer III
Explorer III
You are close
50 amp service (Many threads here show how the outlets are wired) 4 wires. L-1 (hot) L-2 (hot) neutral and safety ground 240 volts divided into two 120 volt legs. double ganged breaker

30 amps.. one hot, neutral and safety ground (3 wires) SINGLE 30 amp breaker.

IF you have 30 installed Make sure it is a single breaker and mEASURE teh voltage BEFORE you plug in.

50 amp optional. Wire as you would 50 amp regular but use 30 amp breakers.. Most 50 Amp RV's will work fine this way.

Now. plugging a 50 amp rig into 30 amps. Use a proper adapter and it will feed BOTH legs on the RV. but you can not use everythign at one time..

If you remember the old Green Acers TV show where Oliver had put numbers on all the appliances and you could not plug in more than I think it was 10.. Well numbers and you can not plug in more than 30

Fridge is a 4.. Coffee pot a 7 (most electric kitchen stuff is 7-10) MIcrowave 11 A/C's 14 water heater 12 that kind of thing. if the total is over 30 CLICK and darkness.
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valhalla360
Nomad
Nomad
Wire sizing depends a lot on the length of the run.

Big difference if it's a 20' run from the main house panel to the pole barn vs 200'.

Search voltage drop. There are tables that will tell you what size cables to use.
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Larryect
Explorer
Explorer
A 3 wire romex (3 + ground) may not cost much more than the 2 wire romex. So I ran 10 awg 3 wire to my RV plug on a 30 amp double pole breaker with a 50 amp RV plug. My current RV is 30 amp so I use an adapter to plug in. But if I ever up size the RV I have two 30 amp lines feeding it instead of one. And, that should really be plenty for home storage/usage. 8 awg may not be much more and would provide 40 amps.

Old-Biscuit
Explorer
Explorer
50A Service uses 2 50A Circuit Breakers ---1 for each Hot

30A service has only 1 30A circuit breaker for the 1 Hot

30A RV plugged into 50A service can only draw 30A on the one HOT
Draw more then the 30A and the 30A circuit breaker inside RV Main Panel will trip

50A RV plugged into 30A service can draw 30A Total..either on 1 Hot or combination of the 2 Hots. Draw more then 30A and the 30A Service circuit breaker will trip.
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ScottG
Nomad
Nomad
luberhill wrote:
Ahh ok so. 59 amp IS a 220 double pole breaker ??
And if you have a 50 amp supply but only a 30 amp MH isn’t that pumping too many amps into the MH ??


Good question but think of it this way; Your RV draws or pulls the current it needs. If it only needs 12A for a space heater then that is all it will draw from the 50 or 30A even though much more is avail.

Ex. your faucet in the house can provide perhaps 5 gallons a minute but you only ask for enough to fill a glass.

time2roll
Explorer II
Explorer II
luberhill wrote:
Ahh ok so. 59 amp IS a 220 double pole breaker ??
And if you have a 50 amp supply but only a 30 amp MH isn’t that pumping too many amps into the MH ??


Yes.

No. The 30 amp RV only pulls what is needed to the limit of the main breaker in the RV.... 30 amps. Consider what happens when you plug a lamp that takes 1 amp into a 15 amp outlet. (normal operation)

luberhill
Explorer
Explorer
Ahh ok so. 59 amp IS a 220 double pole breaker ??
And if you have a 50 amp supply but only a 30 amp MH isn’t that pumping too many amps into the MH ??
2013 Winnebago Sunstar 26HE

Old-Biscuit
Explorer
Explorer
30A to 50A Dogbone adapter
30A Hot feeds BOTH 50A HOTS



30A Outlet 120V-----8ga wire
1 Hot, 1 Neutral, 1 Ground
3600W Total available

50A Outlet 120V/240V----6ga wire
2 Hots (L1/L2), 1 Neutral, 1 Ground
6000W per leg/12000W Total available
Is it time for your medication or mine?


2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31

time2roll
Explorer II
Explorer II
westernrvparkowner wrote:
CA Traveler wrote:
When you use the 30/50A adapter then all 3 hot legs are connected so that you have 120V everywhere in the 50A RV. But you will be limited to 30A total draw.

Yes dual 50A CB. 50A is 120/240V 50A 4 wire single phase just like a home stove. Use 6 gauge wire. 50A effectively gives you 2x 120V 50A circuits or 100A total as it's a rare RV that has 240V appliances.
There arr only two hot legs, not three, in a 50 amp service.

Two hots from the RV and One from the source is Three tied together.

BB_TX
Nomad
Nomad
rv electric

Everything you need to know in the link above. Except the question about a 50 amp rig running on a 30 amp outlet. And as noted above, the 50/30 adapter connects both hot legs in the RV to the one hot leg in the 30 amp service so that everything works in the RV.

westernrvparkow
Explorer
Explorer
CA Traveler wrote:
When you use the 30/50A adapter then all 3 hot legs are connected so that you have 120V everywhere in the 50A RV. But you will be limited to 30A total draw.

Yes dual 50A CB. 50A is 120/240V 50A 4 wire single phase just like a home stove. Use 6 gauge wire. 50A effectively gives you 2x 120V 50A circuits or 100A total as it's a rare RV that has 240V appliances.
There arr only two hot legs, not three, in a 50 amp service.