Test Meter Leads Definitions And Specifications

Pollution Degree

Pollution such as moisture or dust on the surface of test accessories can reduce their insulation capability. There are 4 pollution degrees as defined by IEC 664-1:

  1. No pollution or only dry, non-conductive pollution occurs. The pollution has no influence.

  2. Normally only non-conductive pollution occurs. Temporary conductivity caused by condensation is to be expected.

  3. Conductive pollution occurs, or dry non-conductive pollution, which becomes conductive due to condensation, is to be expected.

    To be found in industrial environments or construction sites (Harsh environments).

  4. The pollution generates persistent conductivity caused by conductive dust, rain or snow.


Transients or overvoltages are an increase in voltages over their normal levels, for a short period of time. The three overvoltage categories as defined by IEC 664-1 where most test accessories are likely to be found are:

CAT I Equipment for connection to circuits in which measures are taken to limit the transient overvoltages to an appropriate low level

Example: Inside electronic equipment.

CAT II Energy-consuming equipment to be supplied from the fixed installation.

Example: Inside household appliances and portable tools or simplified. Any apparatus connected to a wall outlet.

CAT III Equipment in fixed installations.

Example: Installation in buildings, from main fuse box to wall outlet.

Current Ratings

(re our TM Lxxx products)

The current ratings shown are for continuous use at either AC RMS or DC or a mixture of both up to the stated figure.

Plastic Materials

(re our TM Lxxx products)

The majority of plastic components are made of Nylon with a temperature range of -30° C to 100° (-22°F to 212°F).

What is IEC 1010?

IEC 1010 is an internationally recognised standard of design, manufacture and test to which all good manufacturers adhere. This gives the end user confidence when buying IEC 1010 compliant products that the product is the best available and complies with the very latest safety standard.