How does 50 amp work?

[David0725]

Can someone explain how the 50 approach system works? Normally 50 amp is 220 but the rv is not 220 its 110 riright? So how does this work?

[time2roll]

Wired same as your home and works the same. 240v between the hots and 120v from each hot to neutral.
Generally this is called split phase service. Yes virtually no RVs utilize the available 240v.
12,000 watts of electric power available.

[enblethen]

The correct designation for a fifty-amp supply to an RV is 120/240 four wire.

[dougrainer]

RCMAN46 wrote:
The 50 amp 220 volt is the same as the 30 amp 220 volts at your home.
Most RV's loads are 110 volts thus only use one side of the 220 volts as do most of the loads at your home. Most homes only the water heater, electric range and electric furnace use 220 volts and most are 30 amps or less with the exception of some heat pumps. A heat pump in a RV may be wired for 220 volts.

NO HP in a RV is wired for 220 volts. No such HP for an RV has 220 volts. ALL are 110 volts.

220/240 volts in an RV is supplied by 2 separate 120 wires OUT OF PHASE. EACH side is on a 50 amp breaker for 100 amps total supply. The RV does NOT separate the supply. The supply is already separated at the POLE. If the Supply is in phase, the RV will not function correctly all the time. For instance, you have a built in EMS (energy management system) . IT sees if the supply is out of phase. IF IT IS, then you have full 100 amp capacity. IF same phase at supply the EMS will only allow 30 amps total operation. It assumes you have connected a 50 to 30 amp reducer dogbone. IF you think you are connected to a 50 amp service and your EMS shows 30 amp, you have what I call CHEATED 50 amp service. The RV park did not upgrade their supply and wiring for true 50 amp total 100 amp service. This is theft by the RV park. You are paying for 50 amp service and they are NOT giving you what you pay for. The simple test ALL RV'ers need to do is have a multitester and at the Park Pole test the voltage between the 3 and 9 o clock spade slots. 50 amp will show 240. ANY OTHER reading, the pole is NOT 50 amp. Doug

[pianotuna]

It is possible to feed both legs with 110 which are not out of phase, but on two different breakers. However, in that case, 220 is not available.

As the wise souls above have said--it is just like a sticks and bricks home.

[wolfe10]

Yup, no different than in your sticks and bricks home.

240 VAC between the two hots.

Most loads use only one hot, a neutral and ground. So 120 VAC.

Yes, larger loads in a sticks and bricks (electric water heater, central A/C, stoves, etc) are often on two hots, so 240 VAC. A few high end RV's have some 240 VAC appliances as well.

[RCMAN46]

The 50 amp 220 volt is the same as the 30 amp 220 volts at your home.
Most RV's loads are 110 volts thus only use one side of the 220 volts as do most of the loads at your home. Most homes only the water heater, electric range and electric furnace use 220 volts and most are 30 amps or less with the exception of some heat pumps. A heat pump in a RV may be wired for 220 volts.

[valhalla360]

The key part above is the two HOT wires operate exactly 180 degrees out of sync.

AC power is sinusoidal in nature, so it goes from max voltage in one direction of flow to max voltage in the opposite direction (60 times a second for US power grid...aka 60hz). Since they peak in opposite directions, the voltage difference between peaks is +110v & -110v for a total of 220v (nominal voltage...actual voltage will vary). AC powered devices generally don't care about the direction as they expect it to keep reversing.
- If you are powering a 220v device, you draw a circuit off both HOT wires to get 220v.
- If you are powering a 110v device, you draw off one HOT wire and feed it back to the neutral (which connects to ground), giving you 110v.

As most 50amp RVs don't include any 220v powered devices, the circuit box typically breaks the incoming power out into two banks, so half the circuit breakers will feed off one of the HOTs and the other will feed off of the 2nd HOT. You can't combine them to get more 110v than 50amps on each side.

[phil-t]

Decent explainations - additionally, this 50A service of 2 110V, 50A legs only works if the two legs are on different phases of the circuit from the supply.

[William_B]

50 amp is actually 2 legs of 50 amp usually split by the motorhome, a few do use 220. So actually on 50 amp service you have up to 100 amps. On 30 amp service you have only 30 amps.

[craig7h]

I am far from a electrician so I may not get the total picture correct.

50 amp has 2 hot wires, and either 1 or 2 ground. Each 50amp wire carries 110v (actually 120) so adding the two together gives you 220. If you look at your breaker box you will see that the 50amp breaker has two switches, that are tied together is some mannor. Most RVs at the breaker box take and split the 50amp to verious other breakers. Your house does the same thing. It brings in either 100 or 200 amp and at breaker box breaks it down to the various other breakers in the house.

I hope a good electrician joins and can explain better.