I’m fitting a couple of additional 12v sockets to my van (well – actually 2 pairs). They will be used for charging phones but also something like a Dirtworker and a decent floodlight. I was planning on a cable run and relay for each pair.

(a) what gauge of wire will I need – something like the 17A stuff from Halfords?

(b) do I need to run a live and an earth or can I just run one wire and earth to the chassis

TIA.

Why are you using a relay?

Just wire them direct from the battery, with appropriate fuses i.e. 17 amp cable, you would use a 15amp fuse max. Most sockets themselves are rated at 10 – 20amps.

Don’t buy your cable from Halfords, its like buying popcorn at the cinema…expensive! You can run your earth to the body work with a bit of wire brushing to remove the paint and a self tapper, although I think its best to find one of the built in earth points in and around the dashboard, or run back to the battery if its not a long run.

Try http://www.vehicle-wiring-products.eu , they will do everything from the sockets (about a fiver for a 12 socket and cover compared to £9 for a halfords socket with cigar lighter plug, they also do the cable, fuse holders, crimps, the works.

What kind of van? Reason I ask is that some (eg Transits and Connects, possibly more) have the wiring loom in place for a rear socket- but no actual socket unless it was paid extra for (also no fuse in the fuse box).

I bought the wire from ebay: here’s a guide to amps, cores sizes, lengths etc. http://www.engineeringtoolbox.com/amps-wire-gauge-d_730.html

The relay was to make sure the sockets were disabled when the ignition is switched off.

Van is a Trafic/Vivaro. The minibus version does, indeed, have an additional 12v socket in the rear, but even if I found the connector, it wouldn’t do both points.

I’ll have a look at those sites though – ta!

Fair enough, in that case a relay is a good idea 🙂 I like my sockets to work with the ignition off so hadn’t really thought about it.

Good idea about the relay – or perhaps have 2 sockets on always, 2 switched so you have to think about it when plugging something in. Mine are always on – so am always cautious.

What are you going to use for switched live for the relay? Stereo, lights…? How far is that to where you want the relay?

Me – I’d still use any existing loom rather than running cable through the bulkhead and into the engine bay.

Lastly for earth / negative – try and use an existing earth point nearby (possibly rear light cluster?) rather than drill. You dont need to run all the way back to the positive source (actually you shouldnt really do it I afaik).

Battery is under the drivers seat, so my plan is to use a switched live (not decided which yet), put the relays behind/under the dash, then run cables from there. I can get into the areas I want the sockets easy enough. The rearmost sockets will be just behind the tail-lights, so I’ll look around there for a good earth point. There’ll be nothing near the others through, so a little drilling required.

Thanks for the help – that’s saved me a whole length of cable!

I would steer clear of any existing loom, a 12v socket is a relatively high drain item compared to everything else in the car and would risk blowing fuses or damaging the computer. All of the rear lights for example would drain approx 9 amps if they were all on together, less than a electric tyre inflator would draw.