Electrical Industry Canada: Test & Measurement Issue - 7

IMPROVE TEST & MEASUREMENT SAFETY AND EFFICIENCY BY MATCHING THERMAL
IMAGING-ENABLED DEVICES WITH THE APPROPRIATE CAT RATING CNT'D.
The CAT rating method of classification, divided into four parts, known individually as category (CAT) ratings: CAT I, CAT II, CAT III and CAT IV,
provide a quick and simple guide to match the right tools for the job. Understanding what each of these categories means is vital to avoid exposure
to unnecessary risk, including significant injury or death.
In the CAT ratings system, the roman numerals, (i.e., I through IV) refer to the location of a circuit in relation to the power source, defined in terms
of the total potential transient voltage danger.
* CAT I describes secondary circuits not intended to be
connected to the mains electricity supply, such as personal
electronics, and circuits powered by regulated low voltage
sources.
* CAT II is defined as local-level electrical distribution, such as
a standard mains socket and plug-in loads. This category
includes household appliances, such as washing machines,
and portable plug-in power tools.
* CAT III references a building's electrical installations,
including circuit-breakers, wiring, switches and industrial
equipment.
* CAT IV involves the source of the low-voltage power
installation, essentially the power grid infrastructure, such as
underground utility vaults or outdoor power lines.
The CAT rating method of classification, divided into four parts, known individually as category (CAT) ratings: CAT I, CAT II, CAT III and CAT IV,
provide a quick and simple guide to match the right tools for the job. Understanding what each of these categories means is vital to avoid exposure
to unnecessary risk, including significant injury or death.
In the CAT ratings system, the roman numerals, (i.e., I through IV) refer to the location of a circuit in relation to the power source, defined in terms
of the total potential transient voltage danger.
However, determining the appropriate voltage category is only half the story. Simply matching the presumed voltage to the test and
measurement device will not provide adequate safety assurance. Failed electrical units can experience impulse or transient voltages on the order
of many times a particular electrical tool's rating. For example, a line may normally have a voltage of 120 or 240, but the transient voltage from a
lightning strike can generate several thousand volts, causing a short circuit and arcing that may severely injure personnel working with inadequate
equipment.

ELECTRICAL INDUSTRY CANADA

VOLUME 1, ISSUE 1

Electrical Industry Canada: Test & Measurement Issue

Table of Contents for the Digital Edition of Electrical Industry Canada: Test & Measurement Issue