User manual

Wavecom Instruments Portable Appliance Testers Instruction Manual

Technical Information

Class 1 (Earthed Appliance) Construction

(Single basic insulated and protectively earth equipment)

This type of product design provides two safety barriers between all live conductors at dangerous voltages

and the equipment user.

The provision of basic insulation between exposed metal parts and live parts is the first barrier to provide

basic protection against electric shock.

The second safety barrier is by the connection of exposed (accessible) conductive (metal) parts to the

protective earthing conductor (earth wire) in the fixed wiring of the device/Installation.

The protective earthing terminal of the equipment must be marked with the word "earth" or the symbol "E" or

the symbol for Earth Terminal or Protective.

To perform this test a continuous earth loop must be made between the exposed conductive material (metal)

and the TnT appliance tester. This is done by means of connecting the earth lead with the crocodile

clip/probe attached to a GOOD earth point (paint & coatings will not provide effective connections) and the

DUT (Device Under Test) plugged into the TnT appliance testers‟ DUT socket. The Maximum allowable limit is

less than1.0 (ohm).

Class 2 (Double Insulated) Construction

(Double insulated equipment)

This method of construction employs two safety barriers comprising two layers of insulation between

dangerous voltages and the user of the equipment.

The first layer of insulation is formed around the live conductor and is termed „the Functional Insulation‟.

The second layer of insulation is termed „the Supplementary Insulation‟. In Class II equipment, protection

against electric shock does not rely on basic insulation only, but has additional supplementary insulation such

as double insulation or reinforced insulation provided, there being no reliance on precautions in the fixed

wiring of installation.

Class II equipment is marked with the words "DOUBLE INSULATION" or the symbol

For double insulated under Safety Symbols:

Note 1 – Double Insulation is insulation comprising both basic and supplementary insulation.

Note 2 – Reinforced Insulation is a single insulation system with a degree of protection against electric shock,

which is equivalent to double insulation.