Electric Wiring, 3rd Edition

inspection and tests to be carried out 177

Testers

Testers suitable

for

carrying

out the

foregoing tests

are

available from

a number

of

manufacturers

and

some

of

these

are

briefly described

below.

Fig. 11.11 shows two types

of

tester suitable

for

insulation and continuity

tests.

The

'Wee

megger' shown

in (a) is a

compact, self-contained, hand-

operated type with a 500

V

output, and

is

quite adequate for testing domestic

installations. The test voltage

is

obtained from

a

hand-cranked, brushless

a.c. generator,

the

output being rectified

to

give

a d.c.

voltage which

is

constant within a given range

of

cranking speeds.

(a) hand operated

(b) batter ...