ECN Forum Forums General Topics of the Trade General Discussion Area CAT ratings on multimeters.

From IEC 1010:

• Cat I: Signal level, special eguipment or parts of equipment used in telecommunications or electronics.
• Cat II: Local level mains, appliances and other portable equipment
• Cat III: Distribution level mains, fixed installation wiring.
• Cat IV: Service drop wiring to building(outside).

Personally, I'd never use a DMM for any thing closer to the Distribution wiring than the Main switchboard and I would most certainly not use one to test the incoming mains on the pole or at the metering.
IEC 1010 also does mention that DMM's used
for Electrical testing, must have the inputs marked with a certified Cat rating on them!.

This might help: http://www.electricsmarts.com/content/testers_multimeter.asp

bigrockk,
Thanks for that link!.
Having said that, I would never use a multi-meter to test anything more than appliances while they are live.
I normally use Duspol solenoid testers above 230V and for 400V work.
Above this I use a Modiewark for Voltage sensing at voltages 3.3kV-66kV on the end of a Hotstick.
I also have a Phasing out set, for use on 3.3- 66kV.
You have to be Verycareful working with High Energy circuits, these things really pack a punch if wrong connections happen!.