How does 50 amp work?

David0725 wrote:
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?

Ok think of your house for a moment.. Most everything in it is 120 VAC but the "Drop" is 3 wires. 240 volt "Divided" as a cook would say (and that is the best term for it.) If you want the technical description Well.. I can do that. Most folks get it wrong by the way.

The divided means you have to "Hot" legs and a "neutral" which is bonded to Ground.. Your devices. Computers. Cloths washer, Fridge, TV/Radio. lights.. Draw off one of the hot legs with respect to neutral. Now some things.. Like a cloths dryer or a Centeral AC use the full 240 volts.. (This is not so in an RV but it is in a house)

So why 240 volts divided?

Imagine that between your electric coffee maker and the power company transformer there are 2 volts of drop. due to the resistance of the wire EACH WAY.. This means you only have not 120 volt but 116 so it takes a but longer before the Elixer of the Gods is ready to drink.

On 30 amp service this is how it works

Now on 50 amp.. let's say that coffee maker is working opposite your Water heater.. IT also has 2 volts drop each way.. but it's on the OTHER LEG. Since the current is nearly balanced the power say comes in Leg 1. losing 2 volts. passes to leg two where it again looses two volts. but now each appliance has not 116 but 118 volts (The voltage drop. like the voltage, is split is.. "Divided")

This means they can use less copper and get better performance.

But due to the neutral wire (the divider) everything gets close to 120 volt.


Think of a water system.. You have two water pups pushign 120 gallons per minute.. both pushign to the right.. in the middle is a "T" and that T is hooked to a tank holding 50 gallons.

So long as both pumps are pumping the fill flow. the 50 gallon tank water level is static.

But what happens if you are only using power on one leg?
Well then the neutral carries that back to the transformer and of course you get voltage drop both ways.

And the level in the tank change in the water example (The rate of change is affected by the size of the pipe by the way.. and the length)

On a good system it takes a very good Digital meter to see the voltage chagnes properly.