20
221873B
9 Electrical Connections
9.1 Supply Cable Connection
CAUTION: To prevent an induced current from switching the
central heating on, when not required, it is important that the
heating system control cables are separated from the other
mains supply cables.
Open the controls cover door. Remove the two screws securing
the controls facia, see diagram 9.1.
Hinge the control fascia open.
The boiler requires a permanant mains supply through an
external isolator which must also isolate any heating system
controls, see diagram 9.2.
Any heating system controls must not interrupt the permanent
mains supply to the boiler.
Using PVC cable of a suitable length and rating as stated in
Section 1.8 “Electrical Supply”, route the mains supply cable
and connect to the appropriate terminals of the connector block,
restrain with the cable clamp supplied, see diagram 9.2.
Standard colours are, Brown - Live, Blue - Neutral, Green and
Yellow - Earth.
Make the earth cable of a greater length so that if the cable is
strained the earth would be the last to become disconnected.
CAUTION: It is ESSENTIAL to make sure that the polarity is
correct.
9.2 Heating System Controls
All external controls and wiring are required to provide a
minimum of reinforced insulation at 250Vrms between the parts
of those devices operating at mains hazardous voltage and the
user accessible parts af those devices.
Note: For further information, see The Building Regulations
1991 - Conservation of fuel and power, 1995 edition - Appendix
G, table 4b.
If electrical controls are not to be used to regulate the heating
system, do not remove the red link cable.
When any form of external electrical control is being used to
regulate the heating system, remove the red link cable and
connect heating system controls in series.
The mains cable outer insulation must not be cut back external
to the plug.
9.3 Frost Thermostat
If the installation requires protection by a “frost thermostat”,
connect a single pole type, to the appropriate terminals of the
connector.
Keep all cables away from hot surfaces.
9.4 Electrical Test
Carry out preliminary electrical system checks as below:
1. Test insulation resistance to earth of mains cables.
2. Test earth continuity and short circuit of all cables
3. Test the polarity of the mains.
Refit the control fascia.
Diagram 9.1
6964
CONTROLS COVER
SECURING
SCREW (2)
CONTROLS
FASCIA
R2
R1
N
L
Diagram 9.2
7024
CABLE
CLAMP
MAINS
CABLE
SCREW (2)
GROMMET
CONNECTION
BLOCK
RED
LINK
