Accurately measuring current draw

[Faris Raouf]

Following on from the discussions on the Kill-A-Watt in another thread, has
anyone used a proper clamp meter for measuring current?

I'm thinking about buying a cheap-ish one ($80/£40), along with a plug-in
device similar to the Kill-A-Watt in order to compare these two options
(which I consider "slightly-pro" and "consumer" - the clamp meter is only
slightly-pro because it isn't an expensive one - no calibration certificate
etc.

But I'd appreciate any feedback on how accurate the Kill-A-Watt type
products might be before I bother doing so.

What I mean by accurate in this sense is given, say, an 8A power feed in a
data centre, I want to be 100% sure that if my test figures say each server
takes less than 1A under extreme load and I have no more than 8 of them I'm
not going to trip the breaker.

If there's more to this than meets the eye (e.g. all that RMS stuff and god
knows what else that I've forgotten about since I did my Physics) please can
someone pipe up and let me know?


Faris.