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othorton

Member Since: 22 Jul 2019
Location: London
Posts: 104

Electrical Novice - Wiring thickness for extending LED Bar

Hi Chaps,

Hoping for a bit of advice as a wiring newbie. I'll be getting round to wiring up my LED light bar at the weekend. At present, the relay set up doesn't have quite enough wire to get from the bar on the roof to the battery, as I plan to run it up the b-pillar trim and through the headlining. (please note I really do not want to take the dash off to hunt around for an ignition live so think the above plan is the neatest option).

The question is about wire thickness. The light bar draws 12A @ 24V and is 510W. I think I should need probably an extra 6-8ft of wire but am not sure how wire thickness works, much beyond wire which is too thin has the danger of setting on fire (obviously not the plan).

For reference, the loom has its own fuse between battery and relay. I've also bought a trim removal kit and some surplus fir tree studs in order to get the headlining out with minimal damage.

Would really appreciate any advice, in addition to recommendations of where to get the wire from. I already have a soldering iron/wire connectors.

Thanks in advance,

Oliver

29th Oct 2019 7:05am

DuncanS

Member Since: 06 Dec 2013
Location: Cumbria
Posts: 299

2008 Defender 110 Puma 2.4 USW Santorini Black

Hi Oliver.

Something doesn't add up there. it can't be 510W and draw 12A at 24v. That would only give you 288W based on 12A at 24v.

Normally for a lightbar you will use between 3mm and 6mm CSA (cross sectional area) depending on your spec.

We sell cable at K&S McKenzies but its readily available at most decent auto factors. 12 Volt Planet, Vehicle Wiring Products and PoleVolt are probably my three recommended go-tos for online purchases.

cheers North Cumbria Search and Rescue - Team Leader

29th Oct 2019 9:04am

othorton

Member Since: 22 Jul 2019
Location: London
Posts: 104

Thanks very much for getting back to me Duncans. I agree; doing the math, it looks like a 510W bar would be working around 22A rather than 12A. I'll get in touch with GRP 4x4 as perhaps they got their figures mixed up as it does seem there's some confusion here.

Out of interest - is there any issue with using thicker than 6mm gauge wire other than its higher cost?

Thanks,

Oliver

29th Oct 2019 9:40am

rallysteve

Member Since: 10 Feb 2014
Location: Cumbria
Posts: 2238

2002 Defender 110 Td5 DCPU Keswick Green

Nope, use the largest diameter cable you can (within reason) as it will also minimise the voltage drop.

Personally though, 6mm is too thick for your application. . You will find 6mm too big for most crimp terminals and hard to crimp without proper equipment.

Steve 02' 110 TD5 Double Cab Rebuild Thread

29th Oct 2019 10:38am

othorton

Member Since: 22 Jul 2019
Location: London
Posts: 104

Thanks Steve. I'll stick with 4mm then. That's rated to 40A which should be more than enough.

Really appreciate the advice.

Thanks,

Oliver

29th Oct 2019 10:50am

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