I have an outlet in the kitchen that powers the microwave and the under counter lights. The wires register 120V and the plug registers 120V when installed on the wires. The only problem is that nothing runs on the plug. Whenever I tested hot to ground, it was off the scale. Any ideas?

What do you mean by "off the scale". Can't be over 120VAC. Are you sure you don't have the black and neutral switched and a GF is tripping?

There can be high voltage readings if the circuit uses a shared neutral with another circuit, and if that neutral is broken or otherwise opened.

A shared neutral is in a three wire cable with black, red, and white, with two circuits one on each the black and red.

An open neutral is dangerous as it can allow higher than normal voltage to be delivered to a 120 volt circuit.

Best you have this condition checked out and repaired as soon as possible.

First to Mr. Russell: This has a black, white and ground. I am assuming the black is hot. It does not meet the description you described of three wires.

Second to Mr. 641: Off the scale means well over 120acv and completely to the opposite end of the scale from 0. There is no GF on this circuit; it was originally wired as a dedicated circuit for the microwave. When I added under counter lighting I plugged them into the other plug. This is not the first time that we have had a problem, but the first time everything has quit working. Before installing the lights at Christmas, the microwave has had brown out tendencies and has gone off briefly (1 to 2 seconds) on occasion. We currently have everything plugged in by extension cord and they are working fine.

Any other suggestions?

Lets try again. Between black wire and white wire should be 120VAC. Between black and ground should be 120VAC. Between white and ground should be 0VAC. Black to brass on outlet, white to silver, ground to green. What do you measure at the outlet holes? I'd go back to the distribution panel and see if something has crossed. You can only get >120VAC by having another circuited 120VAC somehow get into the same circuit. Let us know what you find. Brian