Which measurement location calls for the HIGHEST measurement category (CAT) rating?

C. The utility meter base / service entrance

B. A lighting branch circuit in a panel

D. A battery-powered circuit board

A meter marked CAT III 1000 V and one marked CAT IV 600 V. Which is the right tool at a 600 V service entrance?

B. The CAT IV 600 V — the category matches the location

A. The CAT III 1000 V — its voltage is higher

D. Neither can ever be used on 600 V

What is the correct order of a “test before touch” (live-dead-live) check?

B. Prove the meter on a known live source, test the circuit, prove the meter on the known source again

A. Test the circuit, then put the meter away

D. Prove the meter after the job is finished

Your meter’s current fuse blew. What goes back in?

B. A fuse of the exact type, voltage and interrupting rating the meter maker specifies

A. Any fuse with the same amp rating

C. A piece of wire until you get a fuse

D. A slightly larger fuse so it does not blow again

You try to read voltage but the leads are still plugged into the amps jack. What is the danger?

B. The amps jack is a near short; across a voltage source it can blow the fuse or cause an arc flash

A. None — the meter will just read zero

Which of these is a reason to take a meter or its leads out of service?

B. Cracked lead insulation, exposed metal beyond the probe tip, or a missing probe guard

C. A low-battery warning that you have just fixed

Rappel pour compagnons Refresher 6 of 10 · about 8 min

Meter safety re-cert refresher

What you’ll learn

Which measurement category belongs where, and why the category beats the voltage number.
Live-dead-live, and why a zero reading means nothing on its own.
What to inspect on the meter, the leads and the fuses before you use them.
The amps-jack trap and the other habits that keep a meter from becoming the fault.

Measurement categories follow the supply from the source inward. Pick the meter for the most severe place you will put the probes today.

The quick rules

Vérifier	What you are looking for
Category and voltage	Category right for the location first; voltage at or above the system you are on.
Case and display	No cracks, no missing screws, battery good, rating marks readable.
Leads	Insulation intact, finger guards on, shrouded plugs, rating at least the meter’s. No exposed metal beyond the tip.
Fuses	Correct maker-specified type and interrupting rating. Test them with the meter’s own fuse check if it has one.
Jacks	Leads in the voltage jack before you touch anything live — not the amps jack.
Proof	Live-dead-live on a known source, every time you test for absence of voltage.

Worked: proving a 600 V motor feeder dead

Location is the load side of a disconnect in the plant distribution: CAT III at least, rated for 600 V or more.
Lock out the disconnect. Prove the meter on a known live 600 V source (or a proving unit): it reads about 600 V.
Test the feeder at the point of work: L1–L2, L2–L3, L1–L3, and each line to ground — six readings, all zero.
Prove the meter on the known source again: it still reads about 600 V. Only now is the zero trusted.

Sur le chantier

Tips

Carry a proving unit so live-dead-live does not depend on finding a live circuit nearby.
Clip one lead on and probe with the other when you can — one hand stays out of the circuit.
Keep the meter’s category and your leads’ category the same or better; the lower one sets your real rating.

Common mistakes

Using a CAT II meter in a CAT III or IV location because it “reads 1000 V”.
Replacing a meter fuse with whatever fits.
Testing for dead without testing the meter.
Leaving the leads in the amps jack after a current reading.

Check yourself

0 right of 0 answered 6 questions · pick one answer each

1.Which measurement location calls for the HIGHEST measurement category (CAT) rating?
2.A meter marked CAT III 1000 V and one marked CAT IV 600 V. Which is the right tool at a 600 V service entrance?
3.What is the correct order of a “test before touch” (live-dead-live) check?
4.Your meter’s current fuse blew. What goes back in?
5.You try to read voltage but the leads are still plugged into the amps jack. What is the danger?
6.Which of these is a reason to take a meter or its leads out of service?

Answers

C. The utility meter base / service entrance — CAT ratings step up as you move toward the source, because the available energy in a transient grows: CAT II at receptacle-connected loads, CAT III in the building’s distribution, CAT IV at the origin of the installation — the service and the utility connection.
B. The CAT IV 600 V — the category matches the location — Category first, then voltage. The category says what transient energy the meter is built to survive at that location; a higher voltage number in a lower category does not make up for it.
B. Prove the meter on a known live source, test the circuit, prove the meter on the known source again — Proving the meter before and after shows it was working the whole time, so its zero reading on the circuit means dead — not a blown fuse or a broken lead.
B. A fuse of the exact type, voltage and interrupting rating the meter maker specifies — Meter fuses are high-interrupting-rating parts matched to the meter. A cheap glass fuse of the same amps can explode on a high-energy fault — which is exactly the moment it is meant to protect you.
B. The amps jack is a near short; across a voltage source it can blow the fuse or cause an arc flash — The current input is a very low resistance on purpose. Across a supply it is a short circuit through your meter, inches from your hands. Check the jacks every time you pick the meter up.
B. Cracked lead insulation, exposed metal beyond the probe tip, or a missing probe guard — Leads are the part closest to your hand. Cracked insulation or exposed metal defeats the meter’s rating entirely. Replace them with leads rated for the same category and voltage or better.

Questions fréquentes

Is a meter re-cert a legal requirement?

That depends on your province or state, your employer and your site. Many employers run periodic meter-safety training as part of their electrical safety program under CSA Z462 in Canada or NFPA 70E in the US. This page is a refresher on the ideas those courses cover, not a substitute for the course your employer requires.

Do I still need PPE with a good CAT IV meter?

Yes. The meter’s rating protects against the meter failing; it does nothing about an arc started by a slipped probe, a dropped tool or a failing piece of equipment. The PPE for energized work comes from your employer’s risk assessment.

Is a non-contact voltage tester enough to prove dead?

No. A non-contact tester is a quick warning, not proof. It can miss shielded cable, DC and a circuit with a weak battery in the tester. Prove dead with a contact meter, live-dead-live.

Voir aussi

Vous voyez une erreur sur cette page? Signalez-la

Merci — votre signalement a été envoyé.

L’envoi n’a pas fonctionné. Veuillez réessayer plus tard.