Clamp sensor voltage to earth
QThe specifications for the Clamp On Leak HiTester 3283 indicate a maximum rated voltage to earth of 300 V rms AC (insulated conductor) (CAT III, 300 V). Can the 3283 be used to measure a 3-phase 400 V circuit?
A
The voltage indicated with the CAT II to CAT IV measurement category is the voltage to ground. For example, with a 3-phase/3-wire or 3-phase/4-wire 400 V circuit, the line voltage is 415 V, but the voltage to ground is 240 V. Consequently, a CAT III (300 V) measuring instrument can be used to safely measure a 400 V line in a location that falls under CAT III. All current testers, DMMs, and clamp-on ammeters that bear the CE mark are designed for use in CAT III measurement of 300 V or higher.
*CAT III: A circuit from the primary side of a device (fixed equipment) drawing electricity directly from a distribution panel or from a distribution panel to an outlet