How does 50 amp work?

AllegroD wrote:
A link and pic as sometimes the visual helps.

RV 50amp

More reading



One thing the pic provides is how your RV handles L1 & L2, at the RV distribution panel. You can, therefore, audit what is wired to each leg, such as ACs, inverters/chargers, and 110 plugs, in case you wish to use high load items, such as space heaters.

Well you can access a 30 amp 240 volt circuit in an RV with a 50 amp service with a breaker like in the link. It would replace the 50 amp main. This allows us too have the cheap heat electric add-on heating to our gas furnace.

50/30 amp Quadplex breaker

The word "phase" can have two different meanings depending on the application. If both are known and understood there is nothing to banter about.

dougrainer wrote:

ScottG wrote:

dougrainer wrote:

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

A good explanation. Only thing wrong with it is that the "out of phase" part - a common misconception.
They (the two legs) are in-phase with each other and maybe easier to understand as two halves of the same phase. On an oscilloscope the signal would look like one complete sine wave. That phase is then split into the two, 120VAC legs.
So your 240VAC service is referred to as Split-Phase.

I think my explanation is better on the Phasing. Please explain in your definition, why, when people try CHEATED 50 amp. They use the same "leg" and then attempt to split that leg onto BOTH sides of the 50 amp RV breaker box, you are still on one phase. This is the Electrical definition of this, NOT MINE. "Two 120 V AC lines are supplied to the premises that are out of phase by 180 degrees with each other". Doug

PS, the definitions also state Split Phase as the same, but I feel stating OUT OF PHASE is better to let lay people understand WHY 50 amp is as it is. It helps explain the 240 between the legs.

No Doug, I'm not going to explain it any further to you because of your history here. While you have often given valuable info in other threads, you are not up for learning anything from anyone here because your ego gets in the way. My apologies for being abrupt but I've been here a LOT longer than you and I'm just not interested in that type of conversation anymore because it's fruitless for both of us.
If you're truly interested in learning, you can Google "Split Phase" and find volumes of interesting information. You might even find that what you learn will make it easier to explain 50A service to others.

Good luck,
Scott

enblethen wrote:
MedCad: Some adapters do not tie the two legs of power. You maybe able to run both AC units on a thirty-amp power feed.
I say again that 50-amp system is 120/240-volt four wire!

I've never seen a properly working commercial RV 30/50 adapter that did not supply 120 VAC to both L1 and L2 on the 50 amp feed. If it does not, it's faulty in my opinion.

MedCad: Some adapters do not tie the two legs of power. You maybe able to run both AC units on a thirty-amp power feed.
I say again that 50-amp system is 120/240-volt four wire!

2 legs of 120v...it's not complicated.

My 50 amp RV are two 110v, one 110v feeds the front of the RV and it's AC and the other 110v feeds the rear and rear AC. If I plug into a 30 amp only the front AC will work.

enblethen,

Great clarification. Thank you.

I will refer you to the National Electrical Code Article 551-46 (C)(4) for correct information.
Paragraph (D) gives information on how the rig is required to be labeled.
It is not two legs of 120 volts. If supply is wired in this manner the neutral will be overloaded if wired from same phase.

Technically a 50A service is 220V. It just depends on how the power is pulled from the service panel I some the RV. Most RV systems use 110V appliances.

An RV uses 2 50A legs of 110V.