Seaward B255 User Manual

Page 15

Operating Manual

Clare B255 Power Tool & Appliance Test Station

Electrical Insulation
To check the insulation, between the ‘live’ conductors (Line and Neutral) and
all exposed metal surfaces, a high voltage a.c. Flash Test is applied. The
voltage will depend on the construction class of the tool or appliance –

1250V

for standard Class I (Earthed) tools and appliances

3000V

for routine testing of Class II (double insulated) equipment

3750V

for Class II equipment following repair or reconditioning operations

Under normal conditions the leakage current at the appropriate Flash Test
voltage should not exceed 5mA

Some Class I equipment may suffer from the effects of high capacitive
leakages associated with exceptionally long supply leads or certain methods
of suppression filtering, or a combination of the two. Under these conditions
a reduced test voltage of 500V or an increased leakage level of up to 10mA
may be permissible – if in doubt advice must be sought from the equipment
manufacturer.

All safety tests must be carried out with the supply switch of the tool or
appliance in the ON position to ensure that all ‘live’ parts are included when
checking insulation. Multi-function tools and appliances must be FULLY
tested with supply and function switches set for each operating mode.

Earth Leakage Current
For equipment fitted with contactor, relay or low voltage ‘electronic’ start
switching devices (often referred to as ‘dead mans handles’), typically those
that require mains voltage to be applied before all operating circuits are made,
it may be impractical to apply a Flash Test to the complete wiring system of
the product. In such cases it may be more appropriate to measure the Earth
Leakage current when the equipment is powered up and running.

Caution! 230V and 110V test sockets are also used as sources
of flash test voltage of up to 1250V.