18
Fault Finding
Preliminary Electrical Systems Check
A. EARTH CONTINUITY CHECK -
Appliance must be electrically
disconnected - meter set on
Ω
(Ohms) x 1
scale and adjust zero if necessary.
a) Test leads from any appliance earth point
to earth pin on plug. Resistance should
be less than 0.1
Ω
(Ohm), check all earth
wires for continuity and all contacts clean
and tight.
B. INSULATION CHECK - Appliance
electrically disconnected, all switches ON.
a) meter set on
Ω
(Ohms) x 1 scale.
Test leads from L to N in appliance
terminal block. If meter reads «0» then
there is a short circuit.
b) meter set on
Ω
(Ohm) x 100 scale.
Repeat test with leads from L to E. If meter
reads less than
∞
(infinity) there is a fault.
NOTE - Should it be found that the fuse
has failed but no fault is indicated - a
detailed continuity check (i.e. by
disconnecting and checking each
component) is required to trace the faulty
component.
It is possible that a fault could occur as a
result of local burning/arcing but no fault
could be found under test. However a
detailed visual inspection should reveal
evidence of burning around the fault.
START
Isolate appliance
and carry out:
A: Earth Continuity
check.
Has inlet fuse blown?
Carry out:
C: Polarity check.
Electricity supply
should now be
satisfactory.
Carry out:
D: Resistance to
Earth check.
Inlet wiring
faulty.
Rectify any
fault.
Isolate appliance and
carry out:
B: Insulation check.
Rectify any fault
including replacing
fuses as necessary.
SOCKET
(face view)
PLUG (with cover removed)
Earth Wire
Green/Yellow
Neutral Wire
Blue
Brown
Blue
Green
Yellow
Green
Yellow
Brown
Blue
( )
FUSE
( )
E
N
L
NO
YES
NO
YES
