with the microwave oven not turned on I got a slight buzz off the microwave casing mounting screw so checked with tester and it was energized. checked a neighbours and found the same thing. Anyone else found this?

Quite normal, 99% of microwaves are Class-1 and require a ground in order to be safe. The buzz you feel is caused by leakage through the mains inlet filter (the same thing as causes the buzz some feel from ungrounded computers).

Ground the casework and the problem will go away.

Quite normal, 99% of microwaves are Class-1 and require a ground in order to be safe. The buzz you feel is caused by leakage through the mains inlet filter (the same thing as causes the buzz some feel from ungrounded computers).

Ground the casework and the problem will go away.

thanks crossy. I immediately put in a good copper ground rod and grounded the case to it. no problems since. was wondering if it was a faulty machine. another question: am I correct in assuming one side of a two wire extension bar could still be hot even tho the switch was in the off position depending on the orientation of the wall plug?

Yes, I've never seen a Thai extension lead with a two pole switch, so if the plug is the 'right' way round you could have live outlets even with the switch off