Plugging 30A 5th wheel into 50A service

klassic wrote:

Me Again wrote:
The way a four wire 240V circuit works you have a ground, neutral, and two 120 hot phases. 240V appliances just use the two hots and ground. A 120V appliance uses one or the other hot and neutral. If neutrals path to the reference source is broken, then a 120V finds the path to the other 120V phase and you have 240 across the appliances, smoke and smell.

Ecample.

Refer on phase one and neutral =120V
Microwave on phase two and same neutral = 120V

Neutral burns up in at power pole(common occurrence). Phase one comes in on hot lead to refer and goes out neutral, then finds no route to source. It does however find a route via the microwave's neutral and on out to the other phase 120V. 120+120=240 volts across the two devices. Repeats across other devices on the two source phases. Low resistance devices burn up one after another working towards higher resistant devices.

Chris

Sorry about the hijack
I understand your example.... But wouldn't the main ground wire have to burn up too for this to happen?
If I yank the neutral wire out of my home's service panel... All the circuit's neutrals still tie into ground.
Or are RV panels wired differently?

http://en.wikipedia.org/wiki/Ground_and_neutral

For Coach Man from this link, this is how RV parks work:

Split phase
Main article: Split-phase electric power
In split-phase wiring, for example, a duplex receptacle in a North American kitchen, devices may be connected with a cable that has three conductors, in addition to ground. The three conductors are usually coloured red, black, and white. The white serves as a common neutral, while the red and black each feed, separately, the top and bottom hot sides of the receptacle. Typically such receptacles are supplied from two circuit breakers in which the handles of two poles are tied together for a common trip. If two large appliances are used at once, current passes through both and the neutral only carries the difference in current. The advantage is that only three wires are required to serve these loads, instead of four. If one kitchen appliance overloads the circuit, the other side of the duplex receptacle will be shut off as well. This is called a multiwire branch circuit. Common trip is required when the connected load uses more than one phase simultaneously. The common trip prevents overloading of the shared neutral if one device draws more than rated current.