sparky

What they all said.

The spark as you call it is most likely because your AC is in the on position and when you plug in that is where the draw is. NOT good. Always shut shore breaker off first before plugging in and unplugging. I go one step further and always shut my air down before doing either one.

Nuf' Sed!

Spark at Plug conn?
You should have the outlet your plugging into powered off.
Other option is main breaker in MH off.
Some people do both.

next time try and turn the circuit breaker OFF in the house for the circuit where you are hooking up to before hooking up the RV and the spark will go away. This procedure should also be done when hooking up at a RV park. Turn the breaker on the post to OFF. The spark is caused because there is something on in the RV, most likely the Convertor. Also turn the circuit breaker OFF before unhooking for the same reason.