In order to check when a fuse is hot you will either need a test light or a dmm. I would get the dmm (digital multimeter). In the states you can pick up one that would fit your needs for about 12 dollars. I would imagine they are fairly cheap where you live too. Make sure the conditions of your car are how you want them when the fuse will be powered. Then take your meter and check for a 12v dc signal. When you find it, that will be a suitable spot.

 

OK great, I can do that. Presumably I'm going to have to use the Add-A-Circuit (or something similar) to give me a wire to test?

 

I would add a circuit. Easiest way and way better than splicing wires. Always best to leave factory wiring alone.

 

you can just stick the lead of the meter in the slot. you should be able to see the metal that the fuse touches. all you have to do is touch that. if you cant get the lead in the slot then you could use a wire or a fuse.

 

Thanks again for the tips. Would you both use the Add-A-Circuit (or a cheap knock-off - the real thing just isn't available over here) thing recommended by redbull? Do you have any thoughts on whether there should be a fuse box slot for an extra cigarette lighter already in existence, just without the wiring to a socket, intended for use in other countries?

 

if the add a circuit (or comperable product) is as easy as it seems I would use that. prior to redbull posting that I would have run a new circuit from the battery because I have never seen that before. I am going to do some research however I may be changing how my Isolator is triggered.

 

I'd be interested to hear what your research turns up. I can buy an Add-A-Circuit type product here very cheaply, not least on eBay, but I'm slightly wary about using something so cheap in my car. Is it the case that it's "just a wire" and the quality of the fuse I attach is what will determine how safe it is? I don't think there's any way to know which of the products for sale is well-made and which is just cheap rubbish - they all look identical!

 

add-a-circuit is suitable for low current applications (under 10A). when using it you must be aware that you are increasing load on the bus in the fuse box and also load on the fuse that serves that section of the fuse box. these reasons are why i limit the load I put on them. there is no concern with safey, they are cheap because there isn't much to them. you also want to be aware of what fuse you "tap". i generally tap lower amperage fuses (<7.5A) and not the larger fuses (>10A).

they are usually used, and suitable for, GPS, phone chargers, radar detectors, LED lighting, etc.

when the desire is for a higher current source, I run a dedicated wire to the battery but use a relay to switch it with ignition (assuming I want it to turn off with the car).

in my car, i have a 10awg amp kit (got it for under $7) that I run to behind the dash. I use a relay on the ignition wire to switch it on/off. I can put 30A on that wire without concern as it is isolated from the car. below, the yellow wire with the fuse is the 10 awg wire. the red and yellow to the head unit are smaller wires that come with the head unit or could come with the cigarette lighter.



as always, wires should be fused for the size they are.

if you desire a lot distribution, you can get an additional fuse block.