Mira Zest 7.5 Installation, Operation And Maintenance Manual page 11

Electrical
1. In a domestic installation, the rating of the electricity supply company fuse and the
consumer unit must be adequate for the additional demand. As these appliances
are high power units, it is essential to contact your electricity supply company to
ensure that the supply is adequate for the appliance. Voltage drop due to local
heavy demand will reduce the shower's performance.
2. The appliance must be earthed by connecting the supply-cable earth conductor to
the earth terminal.
Supplementary bonding: Within the bathroom or shower room, all accessible
conductive parts of electrical equipment and extraneous conductive parts that are
likely to introduce earth potential, must be electrically bonded to earth using a
minimum cable size of 4.0 mm
if mechanically protected).
3. The minimum cable size (cross-sectional area) required is 6 mm
conditions of installation.
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 determine the
cable size which will prevent damage to the cable caused by overheating.
4. To obtain full advantage of the power provided by this unit the shortest possible
cable route from the consumer unit to the shower should be used. The maximum
permissible circuit length is dependent on current demand, voltage drop and cable
size, refer to the IEE Wiring Regulations for further information.
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:
Mira Zest 7.5 kW (240 V AC) at 240 V - 22 Metres
Mira Zest 8.5 kW (240 V AC) at 240 V - 18 Metres
5. A 30 mA residual current device (RCD) should be fitted. This may be part of the
consumer unit or a separate unit.
6. A separate, permanently connected supply must be taken from the consumer unit
to the appliance 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.
7. DO NOT twist the individual cable cores of the live and neutral conductors, as this
will prevent them from entering the terminal block.
8. DO NOT exert strain on the terminal block.
9. DO NOT turn-on the electrical supply until the plumbing has been completed.
2
if the cable is not mechanically protected (2.5 mm
2
2
under normal
2
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