Mira Sprint 7.5 Installation, Operation, Maintenance Manual page 13

Important! The shower circuit should be separated from other circuits by at least
twice the diameter of the cable or conduit and it should not be run through thermally
insulating material or in locations where the ambient temperature is likely to
exceed 30 °C. If any of these conditions are unavoidable it is necessary to perform
the full calculations detailed in BS7671 to determine the cable size. This will
prevent damage to the cable caused by overheating.
2.4. To obtain full advantage of the power provided by this unit, use the shortest
possible cable route from the consumer unit to the shower. It is also necessary
to satisfy the disconnection time and thermal constraints which mean that, for any
given combination of current demand, voltage drop and cable size, there is a
maximum permissible length of circuit.
As a guide only, the following maximum permissible lengths are given for 6 mm
cable protected by a 40A MCB type B and allowing for a 5 Volt drop:
Sprint 7.5 kW (240 V AC) at 240 V -
Sprint 8.5 kW (240 V AC) at 240 V -
Sprint 9.5 kW (240 V AC) at 240 V -
2.5. A 30 mA residual current device (RCD) should be fitted. This may be part of the
consumer unit or a separate unit.
2.6. A separate, permanently connected supply must be taken from the consumer unit
to the Mira Sprint through a double-pole switch, which has at least
3 mm contact separation. The switch can be a ceiling mounted pull-cord type within
the shower room or a wall mounted switch in an adjacent room.
2.7. DO NOT twist the individual cable cores of the live and neutral conductors, as this
will prevent them from entering the terminal block.
2.8. DO NOT exert strain on the terminal block.
2.9. DO NOT turn-on the electrical supply until the plumbing has been completed.
Plumbing and Electrical Schematic Diagram
22 Metres
19 Metres
18 Metres
Power
Low Flow
Temperature
Stop Start
2
13