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CAT ratings belong on the lead, not only the box

Category is about transient energy at the measurement point. A CAT II 1000V lead is not a CAT III panel lead.

Double-insulated silicone test lead
Double-insulated lead — CAT III 1000V / CAT IV 600V, 10A on this SKU.

Procurement often scans for “1000V” and treats CAT as a sticker. Category is about the energy of transients at that point in the installation, not a marketing badge. Voltage on the print is not the same as category.

Double-insulated silicone test lead
Insulation and shrouds are part of the rating, not decoration.

Where each category lives

  • CAT II — plug-in equipment and receptacle circuits
  • CAT III — distribution boards and fixed installation work
  • CAT IV — origin of the installation (service, outdoor supply)

A CAT II 1000V lead is not a substitute for CAT III panel work. The higher number on voltage does not cancel a lower category.

Mark the part

IEC 61010-031 expects the rating on the lead and on replaceable tips. A CAT III carton with an unmarked or CAT II tip is a CAT II assembly. We will not sell a mixed kit and call it CAT III because the wire said so.

CAT-rated test probe
Probe SKU 622 — CE, CAT III 1000V / CAT IV 600V, 10A.
Insulated crocodile clip
Clip SKU 638 — same CAT/current family as the 10A leads.

How THREE-T lists ratings

Most of our 10A silicone leads are specified CAT III 1000V and CAT IV 600V. The strong magnetic connector is CAT IV 1000V at 2A. If a SKU page says “confirm on sample,” the old listing was incomplete — we will not invent a number.

Ask for the IEC PDF that matches the model (YDTL / YDTP / YDTC / AMC). We send the file for that SKU, not a zip of “all certificates.”

RFQ · Test lead kits · Catalog

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