12Volt sockets

[NBMike]

I'm planning to put a couple or three 12v sockets along the boat. Mainly for charging phones and stuff and maybe a net book with Maplins inverter. They're not likely to be in use at the same time ( But may sometimes). Can anyone suggest a size of wire to use for a maximum of 15 meters each way.

Mike

[Tony Brooks]

I'm planning to put a couple or three 12v sockets along the boat. Mainly for charging phones and stuff and maybe a net book with Maplins inverter. They're not likely to be in use at the same time ( But may sometimes). Can anyone suggest a size of wire to use for a maximum of 15 meters each way.

Mike

 

 

In truth NO - not until you tell us exactly the total maximum current they will be expected to supply.

 

VWP list a plug with a 8 amp fuse built in and I am sure the one on my Maplin inverter has a 15 amp use or very close to it, so 3 x 15 (to be sure) = 45 amps. Total run 30 metres so this would imply 40 sq mm cable which is not really practical. If we said that you will use a laptop power supply drawing less current (say 90 watts = 9 amps) and ensure nothing else is in use when that is then 8 sq mm will probably do (8.5 will be better).

 

Whatever sized cable you decide to use fuse the supply end of the cable with a fuse no larger than the cables rated current. However as on the figures above this is likely to be well over 50 amps to ensure acceptable voltdrop fusing at (say) 15 or 20 amps should be fine.

 

If you intend to use an inverter rather than a laptop power supply then my advice would be to put the inverter close to the batteries to minimise the cable run and the run a mains supply up the boat but keep it well away from the 12v stuff and any fuel or gas pipes. In this way the mains cable size is almost irrelevant.

[alan_fincher]

However as on the figures above this is likely to be well over 50 amps to ensure acceptable voltdrop fusing at (say) 15 or 20 amps should be fine.

In my experience if you run a very stout cable that can easily carry (say) 50 amps, and fuse it at 20 amps, you do have to be rather careful about what you plug into the end of it.

 

Whatever that is is unlikely to have cabling on it that will pass 20 amps continuously, (or more, as many 20 amp fuses will happily pass quite a lot more), so there is a good chance of your supply being able to supply enough current to melt wires on your attached device, without the fuse being blown, (if a fault condition has developed).

 

Don't ask me how I know this, though.

[NBMike]

I should have enlarged on the inverter. Its one of those 12v > 19v jobs. Thanks all for input. I think I'll buy a couple of reels of 10mm

[Radio-Ga-Ga]

In my experience if you run a very stout cable that can easily carry (say) 50 amps, and fuse it at 20 amps, you do have to be rather careful about what you plug into the end of it.

 

Whatever that is is unlikely to have cabling on it that will pass 20 amps continuously, (or more, as many 20 amp fuses will happily pass quite a lot more), so there is a good chance of your supply being able to supply enough current to melt wires on your attached device, without the fuse being blown, (if a fault condition has developed).

 

Don't ask me how I know this, though.

Out of interest if you use cigar lighter type sockets, plugs are available that have a glass fuse to protect the cable after the socket.

[bottle]

Alan

 

I am sure you know that cable protection (fuse etc.) should always protect the cable so when reducing the cable size a 'fuse' should always be fitted just before the reduction.

 

 

 

As for 'cigar lighter sockets' I have never liked them, they do not make good connections.

 

I much prefer the Din type. They actually click into place.

[Radio-Ga-Ga]

As for 'cigar lighter sockets' I have never liked them, they do not make good connections.

 

I much prefer the Din type. They actually click into place.

 

Agreed, tho they seem pretty popular so thought the fused type plug worth a mention, I only have one, near the door for plugging a sat nav into.