12V Help from resident leccy pro's?

[juc33_prado Advanced Member Find all posts View Profile Close juc33_prado]

Hello any resident eletrical pro's,

Just about to run cabling to a few spots from second battery;

I have attached a diagram of it, i have 2 questions if anyone cares to answer them. The q's are on on the diagram too...



Thanks in advance.

SAMUEL

[maulbeagle Senior Member Find all posts View Profile Close maulbeagle]

normal auto wire you get from supercheap or repco will be fine for the front socket, I think it's 4mm roughly ? Also, two connections to the fuse is fine, but remember if one of those circuits trips the fuse the other circuit will be off as well.

[Chillihilli Lurker Find all posts View Profile Close Chillihilli]

It's not the way I would do it.

Your fuse is a good size for 8 AWG. That's fine.
The problem is if you have a device fault or short in the device or cable, you can put up to 30 amps across a cigarette socket and device designed for less than 10 amps. That is not good.

The reason you put the fused block in the back is to "branch" off your larger cable to smaller cables and lower power circuits. Your cigarette light is another branch.
I would rather run a separate wire from your fused block in the back. I would run a length of 4mm TYCAB twin core (rated to 22 amp) and run it off a 15 amp fuse for that circuit. It also means if you have a problem on that circuit you can isolate and diagnose the fault a lot easier, rather than knocking out your entire system.

Cheers Chilli.

[Guest Close Guest]

A fuse is meant to protect the wire and should be as close as possible to the power source.

So the fuse should ideally be less or equal to the "ampacity" of the wire. Here is a chart
http://www.cerrowire.com/ampacity-charts

Assuming that your 8G in your diagram is 8awg, then use the 60deg column to determine ampacity, which in your case = 40A.

Technically, if you are using 8awg all the way, then a single 40A fuse right near the battery will suffice. However, this is not the case as you most likely may not have 8awg wire connecting the cig sockets and anderson plugs to your devices. So you would want to fuse each junction according to the maximum ampacity of the wiring. eg. a typical cig lighter cable is rated to 10 or 15A. If there is no fuse within the plug, then your cabling needs to have a 10/15A fuse.

[juc33_prado Advanced Member Find all posts View Profile Close juc33_prado]

thanks all, will separate the ciggy points with a different fuse direct from battery. ta.

SAMUEL

[LNGRNGR Junior Member Find all posts View Profile Close LNGRNGR]

What these guys said is what i would have said. Put a fuse block in the front and back for all your smaller accessories, if you only have one in the fornt now you'll have room for future expansion and its all neat and tidy when trying to find faults.