Should I install a fuse block for accessories?

[apsilon]

OK, electrical is an area where I think I understand the basics but there's a lot of room for things to go wrong.

I'm looking at adding driving lights, UHF and possibly an inverter in the near future. Rather than tapping/butchering the OEM wiring I'm thinking of running wire directly from the battery to a new fuse block holder thing. Each device can then be wired to this. Does that sound like a good idea?

How do I work out the wiring size to run from the batter to the fuse block? Wiring it this way will obviously also make anything conencted via it always "on". Is there a simple way to avoid that?

Sorry for the noob questions but I'm sure someone here will have done something similar in the past and can offer advice and tips.

[marcthelegend]

yep run it to a distribution block, run the cables from the to your device and put a relay in place, wire the relay to power / lights etc. and they will come on when you want and turn off when you want. Its alot neater this way! as for cable size, 4 - 2 gauge off the battery is more than enough using the method of amps = watts / volts (eg for 200w driving lights 200/12 = 16.667 amps) the get the appropriate cable thickness, jaycar says what current the cable will carry, 8 gauge does 56 amps, or 650watts.. Good luck!

Marc

[dolphin]

if your considering mounting this fuse block unit under the bonnet, go and have a look at the marine types available [ boat supply shops ] this way you also get something abit more water proof . a friend has one of these set up in the rear tray of his toyota ute as he runs heaps of lights / fridge / etc.

[apsilon]

Thanks guys.

I was thinking of mounting inside, under the dash somewhere. One of the main reasons is to avoid having to constantly run power for the different devices through the firewall. Run it once to the block and then go from there.

Any tips on the gauge of wire to select?

[marcthelegend]

Thanks guys.

I was thinking of mounting inside, under the dash somewhere. One of the main reasons is to avoid having to constantly run power for the different devices through the firewall. Run it once to the block and then go from there.

Any tips on the gauge of wire to select?

inverter i'd say 8 gauge, more if you have a big inverter, UHF doesnt need anything big, i'd say 12 - 16 gauge (thin but not speaker cable thin), driving lights, i use 8 gauge to run 4 x 100 watts and the cable handles it really well, u'd be able to use this without any problems for up to 2 100watt driving lights.

Depending on whether you want to keep your options open for the future, or just leave it at that decides what cable size goes from the battery to the fuse block, for all that you'd best use 8 gauge for 2 driving lights + small / medium inverter and UHF, or 4 gauge for something like 4 driving lights, a large inverter and UHF(this option would leave room for further upgrades like stereo etc). 8 gauge supprts 56amps while 4 does 110amps.

I find its always best to overestimate and get the bigger cable as it give you future options without the need to rip out the old cables and put down bigger ones, if you undersize your cables you run the risk of melting the cables and causing a car fire, which is very very bad lol

Regards

Marc

[apsilon]

Cheers, that helps a lot.

[apsilon]

Encouraged by the fact I got my driving lights installed and working without any smoke last weekend, I'm going to pick up the parts to do this over this weekend.

I'm looking to run a line into the back for a future fridge. Is there any reason not to run this as constant "hot"? Seems correct to me but just want to make sure I'm not missing something obvious.

[linou]

As long as you have a the line fused, so if something does happen, it does not allow current to continuously run from battery to body. The fridge line to the back of my Paj is always on - runs of the second battery - but I have a large fuse in the engine bay very close to the battery...just in case!

Good luck with the project, always very satisfying when all installed and working.

[apsilon]

Yes, it'll be fused twice. One near the battery on the run to the fuse block for the whole fuse block circuit and then again at the fuse block itself for each individual circuit.

I was very happy nothing went wrong and caught fire last weekend Hopefully I can repeat that experience.

Evetually I do plan on installing a second battery and will then just switch this fuse block I'm installing over to that. In the mean time it'll really only be running the UHF I'll be installing next and the other circuits will be spare awaiting uses.

I've just been searching around and have decided to take the easy route and am going to grab a Painless Wiring 7 circuit fuse block. It gives me 3 constant hot circuits and 4 ignition circuits. Probably overkill in terms of the number of circuits but better to have too many in the long run than have to do it again if I find I need more.

Thanks.

[arrow]

probably overkill in terms of the number of circuits

No, initially spread your services around evenly rather than potentially having a couple of services on the one circuit. Makes it a whole lot easier to trouble shoot is you blow a fuse.
We installed an 8-place fuse block recently for a dual battery set-up. Not sorry we did that at all.

[apsilon]

I plan to have each device on it's on circuit, I just can't think of 7 devices I'll want or need.

[arrow]

Spotties, floods, CB, winch, rear mounted camp/work light, on board compressor, air horns, frig = all circuits used!!!!!!!!!!

[apsilon]

I admit I haven't looked into how winches and compressors are wired but I'm thinking this fuse block is just for in cabin devices, so UHF and fridge yes, winch and compressor probbaly not. I'll run a seperate fuse block under the bonnet later on. This is just a way of running power into the cabin once and distriuting from there.

Good points though, it porbbaly isn't overkill afterall.

[apsilon]

OK I'm about 98% of the way through having this done but have noticed something that I think is a problem.

I've used a prewired kit that has 3 constant hot and 4 ignition hot circuits and also has an integrated relay. I've wired the relay to a power source that is only hot when the ignition is on and the ground pin to a ground point as per included instructions. The only thing left to do is connect the main relay power feed to the battery positive terminal.

This is where I think things come unstuck. With the ignition on if I put a meter between the wire that's supposed to (but not yet) connect to the battery and the negative battery termainal I can see 12v.

Is this right? I was expecting to see no voltage? I'm worried that if this is already live and I connect it to the battery it's going to create a short. Or am I causing the relay to ground out via what should be the in cable because I'm connecting it to the negative battery terminal and everything will be fine if conencted to the positive terminal?

Help!!

[marcthelegend]

relays can be a little tricky, but if you look at whats printed on the top of the relay, its pretty straight forward and tells you what goes to what .. if memory serves correct, you have to connect pin 85 and 86 to ignition and minus (follow the diagram on the relay) and 30 to battery positive and 87 to the fuse block.

Good luck

Marc