RV Watts Up

What’s a WATT?

Phil May of TechnoRV takes us through the basics of electrical power, and de-mystifies some of the terminology.





First of all, what is electricity?

  • Movement of electrons
  • Measured in terms of Volts, Amps and Watts
  • You can think of electricity like water:
  • Volts is like water pressure, Amps like the rate of flow of water and Watts is like the amount of work you can do with water (e.g. think of a water turbine people would use to grind flour or run a factory)
  • Frequency is the number of cycles per second. Our house outlets are 120V 60Hz which means 60 cycles per second. Are appliances expect that frequency and if they receive something different they can do unpredictable things.

I understand that, but what about the terms Ground and Neutral … are they the same thing?

  • They’re similar, but not the same thing.
  • Electricity is like water in that it flow downhill … i.e. from high voltage to low voltage.
  • Ground is defined as the voltage of the ground = 0 volts
  • Neutral is the return or the wire that is used to complete the circuit. It is tied to ground by the electric company or at your main breaker, BUT it is different. The Neutral carries current, your Ground doesn’t.

I’ve heard people talk about ‘Open Ground’, Open Neutral’ and ‘Reverse Polarity’, why are they a bad thing?

  • Ground can save your life as it will cause the circuit breaker to blow if you have a fault such as a live chassis or case. If there is no connection to ground, the electricity from the case could flow through you if you touch it, giving you a dangerous electrical shock.
  • An Open Neutral is especially dangerous with a 50A connection as it can allow 240v into your rig.
  • Reverse polarity can cause your electronics to fail as they expect the live and the neutral to be the right way around.

So now your RV can connect to 30A or 50A … what’s the difference?

  • 30A has three pins – a Ground, Neutral and a Live. The live will carry a maximum of 30A.
  • 50A has four pins – a Ground, Neutral and two Lives, both of which can carry 50A giving a total of 100A.
  • If your RV is a 50A RV, each one of those 50A lines will go to its own circuit breaker inside and will run one half of the coach.

So that’s why you seem to be able to run so many more appliances when your connected to 50A.

  • You got it. In fact you get a total of 12kW vs 3.6kW.

What happens when things go wrong?

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