[Boatanchors] Fluke 80K high voltage probes... why "energy limited circuits" only?

[Rick Poole WA1RKT]

Fluke makes a popular family of high-voltage probes for DMMs, the 80K series (6, 15, and 40 KV).  They're intended for Fluke's DMMs but are theoretically useable with any DMM with a 10-Mohm input impedance.

For each of these probes, the instruction sheet emphasizes that "the probe can only be used to make measurements on energy limited circuits within equipment... DO NOT use this probe to measure high voltages on power distribution systems.".

These probes are for measuring voltage, not current.  So, why the restriction on power distribution systems?  5 KV is 5 KV for measurement purposes no matter if it is capable of supplying 1000 amps or 1 milliamp.  So why should the voltage-measuring probe or DMM care if the voltage source is a power distribution system or not?

Hard to tell if the plate voltage on a KW linear would be considered an "energy limited circuit" or a "power distribution system" within the context of that warning.

Rick WA1RKT 
Londonderry, NH 
Catch me on 14.300 MHz Intercon / MMSN most days