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9

Select the right test tool:

• Choose a test tool rated to the highest

category and voltage for which it could

possibly be used (most often 600 or 1000

volt CAT III and/or 600 volt CAT IV).

• Look for the category and voltage marking

near the recessed input connectors of your

test tool and a “double insulated” symbol

on the back.

• Verify your test tool has been tested and

certified by two or more independent

testing laboratories, such as UL in the

United States and VDE or TüV in Europe by

looking for the symbols of these agencies

on (the back of) your test tool.

• Make sure that the test tool is made of

a high-quality, durable non-conductive

material.

• Check the manual to verify that the

ohms, continuity and capacitance circuits

are protected to the same level as the

voltage test circuit, to reduce hazards

when the test tool is used incorrectly in

ohms, continuity or capacitance mode (if

applicable).

• Verify that the test tool has internal

protection to prevent instrument damage

when voltage is incorrectly applied to

an amperage measurement function (if

applicable).

• Make sure that the amperage and

voltage of your test tool’s fuses meets

specifications. Fuse voltage must be as high

or higher than the test tool’s voltage rating.

• Be sure to use test leads that have:

- Shrouded connectors

- Finger guards and a non-slip surface

- Category ratings that equal or exceed

those of the test tool

- Double insulation (look for the symbol)

- A minimum of exposed metal on the

probe tips

Safety is everyone’s responsibility but

ultimately it is in your hands.

No tool by itself can guarantee your safety

when working with electricity. It’s the

combination of the right tools and safe

work practices that gives you maximum

protection. Here are a few tips to help you

in your work:

Make sure you always comply with (local)

regulations.

Work on de-energized circuits whenever

possible.

Use proper lock-out/tag-out procedures. If these

procedures are not in place or enforced, assume

that the circuit is live.

Use protective gear when working on live

circuits:

• Use insulated tools

• Wear safety glasses or a face shield

• Wear insulated gloves, remove watches or

jewelry

• Stand on an insulated mat

• Wear flame resistant clothing, not ordinary

work clothes

Inspect and test your test tool:

• Check for a broken case, worn test leads or

a faded display.

• Make sure the batteries still deliver

sufficient power to get reliable readings.

Many test tools have a low battery indicator

on the display.

• Check the test leads resistance for internal

breaks while moving the leads around

(good leads measure 0.1-0.3 Ohm).

• Use the meter’s own test capability to

ensure that the fuses are in place and

working right (see manual for details).

Apply the appropriate working

practices when measuring on live

circuits:

• Hook on the ground clip first, then make

contact with the hot lead. Remove the hot

lead first, the ground lead last.

• Use the three-point test method, especially

when checking to see if a circuit is dead.

First test a known live circuit. Second,

test the target circuit. Third, test the live

circuit again. This verifies that your test

tool worked properly before and after the

measurement.

• Hang or rest the test tool if possible.

Try to avoid holding it in your hands, to

minimize personal exposure to the effects

of transients.

• Use the old electrician’s trick of keeping

one hand in your pocket. This lessens the

change of a closed circuit across your chest

and through your heart.

Fluke: Where safety is built in

Overvoltage

Installation

Category

Working Voltage

(DC or AC RMS

to ground)

Peak Impulse

Transient

(20 repetitions)

Test Source

(Ω = V/A)

CAT I

600 V

2500 V

30 Ohm source

CAT I

1000 V

4000 V

30 Ohm source

CAT II

600 V

4000 V

12 Ohm source

CAT II

1000 V

6000 V

12 Ohm source

CAT III

600 V

6000 V

2 Ohm source

CAT III

1000 V

8000 V

2 Ohm source

CAT IV

600 V

8000 V

2 Ohm source

Table 2

Use meters with these markings:

1000 V CAT III or 600 V CAT IV

Transient test values for overvoltage installation categories.

(50 V/150 V/300 V values not included)

Use protective equipment such as safety glasses and

insulated gloves