Potterton PRIMA 30C User Manual page 17

INSTALLATION INSTRUCTIONS - Page 17
Figure 13 PRINCIPAL OF WIRING
WIRING
WARNING: This appliance must be earthed.
The boiler and all external control circuit wiring must be
supplied from the same single isolating switch and should be
fused at 3A.
Care must be taken to ensure that all wiring to the boiler is
kept clear of sharp edges and hot surfaces.
Ensure that the earth conductor is longer than the L, N, and
SWL from the point of anchorage, so that the current
carrying conductors become taut before the earth conductor,
if the cable is pulled out of the cable clamp.
The boiler terminal block which is situated in the control box
is not designed to accept wiring from all the on site controls
and therefore the installer will usually need to incorporate a
suitable junction box or Potterton Electronic Programmer.
The principle of wiring is shown in Fig 13. It should be noted
that the pump must be wired directly to the boiler terminal
block on FULLY PUMPED systems and to the junction box
or programmer on combined GRAVITY HOT
WATER/PUMPED CENTRAL HEATING systems.
Figure 14 ACCESS TO THE BOILER
ELECTRICAL TERMINAL BLOCK
Remove control box securing screw and lower the control
box to gain access to the boiler terminal block.
Figure 15 WIRING THE BOILER
FOR A FULLY PUMPED SYSTEM
Route a four core cable through the plastic bush at the rear
of the control box and the cable clamp as illustrated Fig 15,
and connect it to the boiler input terminals as follows:-
Permanent live to terminal marked MAINS 'L'
Neutral to terminal marked MAINS 'N'
Earth to terminal marked MAINS +
Switched live from external controls to terminal marked
MAINS SwL.
If there are no secondary controls fitted connect the SwL
terminal to permanent live in the external junction box.
Secure the cable within the cable clamp by tightening the
securing screws.
Following the pump manufacturers instructions connect the
pump supply wires to terminals marked PUMP, L, N and 4"
on the boiler terminal block.
Route the cable through the plastic bush in the rear of the
control box and cable clamp as illustrated Fig 15. Secure
cable in cable clamp by tightening the two securing screws.
Close control box and replace securing screw.
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