Wiring

Additions to 12 volt wiring on boats are often done without much thought and without sufficient care. It normally works for a time but may become unreliable.

Inspect your wiring and if the wire is old and corroded (evidence of blue powdery corrosion) replace with new wire using properly crimped connections that are heat shrink sealed and possibly of heavier gauge. If your wire is still clean uncorroded copper it should be ok especially if you clean it with emery before crimping.

Inspect contacts/connectors and terminals to make sure they are clean and not corroded.

Check for security of crimps by giving them a tug. Any that come loose must be renewed.

Any exterior or in mast wiring should use tinned wire. Inside tha cabin untinned wire will suffice.

When fault finding bypass possibly faulty wiring with a temporary twin wire, ideally fused,running direct from the battery to the load.

Original fit switches become unreliable and replacement panels with circuit braekers can be fitted to replace them.

Take time to understand you boats wiring. You may well be able to rewire it in a more logical fashion.

Fuseholders strung in the wiring are a common cause of intermittent contacts and should be replaced with securely fixed fuseholders.

Select your wire based on the table in The RCD directive referenced below.

For low current circuits the allowable voltage drop is normally the determining factor. You can calculate this based on the length of run (formula given includes there and back allowance) and the mm^2 conductor area.

For higher currents such as winches and thrusters the heating effect of the current is also detemining factor and the ampacity of the cable must be taken into account.

Resources

Sources of tinned wire and crimps are ?

Sources of switch panels are ?

References

Information on metric wire sizes based on the Recreational Craft Directive here RCD Wiring Standards

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