Volvo Penta TAMD74A, Operator'S Manual

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Maintenance: Electrical system
Electrical installations
Defective electrical insallations can generate stray
current from the electrical system. Stray current can
impair the galvanic protection for the propeller, pro-
peller shaft, rudder, keel, etc. and cause damage
due to electrochemical corrosion.
IMPORTANT! Service on the boat’s low-cur-
rent circuit should be carried out by a person
with electrical training and experience. Installa-
tions or work with shore power equipment
must only be performed by an electrician
qualified for high-current installations.
The following points must always be taken into
account:
1. If the shore power line is connected, it must have
a protective earth on land, never in the boat. The
shore power equipment must also be equipped
with an earth fault breaker.
The shore power equipment (transformer, con-
verter, battery charger, etc.) must be intended for
marine use where the high-voltage section is gal-
vanically isolated from the low-voltage section.
2. Electric cables must be run and clamped so
there is no risk of it being exposed to chafing,
moisture or bilge water in the keelson.
3. Protective earth for e.g. radio, navigation equip-
ment, rudder, bathing ladder or other equipment
in which there are separate cables for protective
earth must be collected on an earth connection
that is not connected to the engine, gear wheels
or reverse gear.
IMPORTANT! The engine or reverse gear
must never be used as an earth connection.
4. The battery must have a main switch connected
on the positive (+) side of the battery. The main
switch isolates all consumers and is turned off
when the boat is not in use.
5. If an extra consumer battery is used, there must
be a main switch (1) between the (+) terminal of
the consumer battery and the fuse strip for the
boat’s electric equipment. The main switch iso-
lates all consumers connected to the consumer
battery and is turned off when no longer needed.
Equipment connected to the consumer battery
must have separate switches.
For simultaneous charging of two independent
battery circuits, there should be a separate
charge distributor (accessory) fitted to the stan-
dard alternator.
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