Volvo Penta 22 Series Instruction Book page 44

Electrical installations
Leakage current from the electrical system can be caused by incorrect installation of electrical equipment.
Leakage current can in turn damage the galvanic protection of components such as the drive, propeller, propeller
shaft, rudder stock and keel and cause damage by electrolytic corrosion.
IMPORTANT! Work on the boat's low tension circuit should only be carried out by qualified or experienced
persons. Installation or work on the shore power equipment must only be carried out by electricians
authorized to work with high-voltage installations.
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The following should always be observed:
1. If shore power is connected, the protector ground
should be ashore, never in the boat. Shore power
should always have a ground fault circuit breaker.
Shore power units (transformer, rectifier, battery
chargers etc.) must be intended for marine usage
and the high tension circuit must be
galvanically separated from the low tension
circuit.
2. Route and clamp electric cables so that they will
not be exposed to rubbing, damp or bilge water in
the keelson.
3. Protective grounds for the radio, navigational
equipment, rudder, bathing steps or other
equipment with separate ground leads must be
connected to a common ground terminal which is
not connected to the engine, drive or reverse gear.
IMPORTANT! Engine, drive or reverse gear
must never be used as a ground point.
4. There must be a main switch connected to the
starter battery positive (+) terminal. The main
switch should cut off power to all power consuming
equipment and should be switched off when the
boat is not in use.
5. If an auxiliary battery is in use, a main switch (1)
should be connected between the battery (+)
terminal and the electrical system fuse block. The
main switch for the auxiliary battery must cut off
all power consuming equipment connected to that
battery and be turned off when power is no longer
needed. All equipment connected to the auxiliary
battery should have separate switches.
To simultaneously charge two independent battery
circuits, fit a Volvo Penta charge distributor
(accessory) to the regular generator.