50 amp RV outlet

DrewE wrote:

Bobbo wrote:

wnjj wrote:
The other thing that can fry stuff in a RV is a standard 4-pin 50A connection with an open neutral. That can cause half of the devices in your RV to see much higher than 120V and why many suggest installing some kind of protection system.

Yes, an open neutral on a 50 amp rig will fry stuff. However, it doesn't fry just half of the stuff, it fries everything. Since there is no NEUTRAL, everything sees the full 240v. Fortunately, an open NEUTRAL is rare.

Everything doesn't see 240V, not at the same time. The 240V is split between the two legs; the one with the higher load and hence lower impedance sees proportionally more of the voltage, and the one with the lower load sees less voltage. In theory, if the legs were perfectly balanced, there would be no change in their voltage and no problems at all; indeed, in that situation, there is no neutral current, so it's effectively an open circuit anyhow. The legs are not perfectly balanced in normal cases, though, and how far out of balance they are can change rather rapidly and spectacularly if devices are damaged and become open circuits (or short circuits, followed by their circuit breaker tripping, making an open circuit).

A broken neutral is indeed very bad news. It does not, however, lead to 240V at all the outlets and loads.

Agreed that all items don't see 240v AT THE SAME TIME. However, when leg 1 sees 240v and blows out its 120v items, they stop pulling power and leg 2 now sees the 240v. So, saying they don't see 240v AT THE SAME TIME is accurate. It is milliseconds between the two.