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With an inverter, 300w - 600w peak, can you wire it directly into a 12v power point on the boat? Say an existing 12v plug socket or has it got to be wired direct to the battery?

Asked by: Jason Hulme  | 7.02pm, Thursday 22 October

WW says:

A 12V socket is really for a maximum of 120W- the cabling will only be able to support this. If you try and use an inverter on this cable, you should blow the fuse- if not you may end up melting the wire! Most 12V sockets on boats will only have a 4mm2 cross sectional area wire and struggle even with 10A loads for long periods of time.
The inverter needs to be wired ideally to the battery master switch output, with a suitable master fuse inline, as close to the master switch as possible. You will also need to use suitably thick cables, both to prevent them overheating, but also to reduce voltage drop- which would make the inverter shut down prematurely. For a 600W peak inverter (which can draw up to around 60 amps) you will need cables that are at least 15mm2 in cross sectional area, if the inverter is fairly close to the batteries (within a metre or so)- thicker would be better- say 25mm2- for best performance. Thinner wires risk overheating.
Most supply cables for the general cabin systems will not be able to cope with even a small inverter wired in directly, without the potential for overheating cables and poor performance of the inverter. If you are in any doubt how to fit the inverter properly, then ensure that you consult a marine electrician. While 12V systems cannot kill by electrocution easily, they can cause fires if they overheat- while the 230V output can kill.

Mark Langley  | 9.11PM, Thursday 22 October

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