Fluke Scopemeter 123 and 3 Phase.

[MBaker]

Hi,
Just getting to grips with my newly acquired Scopemeter 123 and while reading the manual it says "Do not connect the ground wire to voltages higher than 42v peak from earth ground".
 Does this mean that I can't connect 'Input A' to one 240v phase and the 'COM' to another 240v phase to measure the average across two phases as I would do with a standard multimeter?

Don't want to damage my meter.

Thanks in advance.

Mike.

[johansen]

that's why they make x10, x20 and x100 probes.

[MBaker]

Many thanks Johansen. I won't ask any further questions. I'll go and educate myself on x10 probes etc to find out why.
I think that 2 hour video on here of scopes for dopes would be a good place for me to start so I'll go and watch that.
 Thanks for the reply.

Mike.

[fubar.gr]

The COM lead is supposed to be connected to mains earth only.

Does this scope have a MATH subtraction function (A-B)? Then you can do a differential measurement using both channels.

Else, you'll need a differential probe like this: http://en-us.fluke.com/products/all-accessories/fluke-dp120.html#overview

[johansen]

that scope meter is designed for floating operation at up to 600 volts at 400hz, you'll see in one of the videos on the website he clips the black lead to L1 and the probe to L2 of a vfd and he shows you the output.

That said, it appears fluke is too righteous to ship you a x10 probe with the fluke 123 by default, its an optional accessory 
(yes, be very careful that you don't connect the ground lead of a second probe and make a current loop, blowing both leads up..) (though it might have double fused inputs, idk)

[MBaker]

Thanks all.

Yes it does have a Phase setting where it will measure the differential and deg between input A and B. Found it last night while playing around with settings.
 So looks like the correct way is to ground the Com lead, then connect probe A and B to a phase each with their ground leads removed and use Phase mode.

Yes it does seem like everything is an optional extra with Fluke. It is great kit and I'm always pleased with the quality and available settings.
 I guess you get what you pay for, then if you pay extra and then some more you get what you need.

I looked at buying an optical interface lead to do firmware upgrades but the price is just ridiculous for what it is. Think I'll stick with the firmware I've got.