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DuncanS



Member Since: 07 Dec 2013
Location: Cumbria
Posts: 245

United Kingdom 2008 Defender 110 Puma 2.4 USW Santorini Black

Always assume the figures for wattage and current draw are garbage. Only very few manufacturers (Rigid, Laser etc) quote somewhat realistic figures rather than theoretical ones. I tend to use one of these for unknown circuit draws.LINK HERE although cheaper ones are available.

24A would seem realistic for a 50" Bar. I tend to use (depending on cable run) 4.5mm2 (42a) by default for lightbar wiring as it covers every base I've come across so far and I usually fuse at 25ish amps.

As you have discovered, the wiring is too thin for the bar, but the fuse is blowing due to the high current, not because the wiring can't handle it, the two are mutually exclusive. Also when sizing cable we need to take into account distance to account for voltage drop.

A really helpful guide has been written by 12 volt planet and is available here and is well worth a read:

https://www.12voltplanet.co.uk/cable-sizing-selection.html
https://www.12voltplanet.co.uk/fuses-guide-uses.html

There is also a voltage drop calculator on there for those wanting to learn more and have a play around. North Cumbria Rescue & Response - Team Leader

Electrical Division @ K&S McKenzie Ltd, Carlisle

Post #810193 14th Jan 2020 12:29pm
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BaronDefenders



Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 171

United Kingdom 2004 Defender 90 Td5 CSW Santorini Black

Thanks for all of that info, Duncans! Really useful!

Well, if nothing else, I’ve learnt a bit about electrickery. 2004 Td5 90
2012 TDCi 110
1958 Series 2 88

Instagram: @BaronDefenders

Post #810202 14th Jan 2020 2:13pm
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Supacat



Member Since: 16 Oct 2012
Location: West Yorkshire
Posts: 8180

United Kingdom 2013 Defender 110 Puma 2.2 XS DCPU Keswick Green

Why not put a meter into the circuit and see what the actual current draw is, instead of going off 2nd hand info?

Out of interest why didn't you use the wiring kit the light is supposed to come with?

Post #810230 14th Jan 2020 8:04pm
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90 Dreamer



Member Since: 13 Jul 2019
Location: Oop North
Posts: 1120

United Kingdom 2016 Defender 90 Puma 2.2 HT Corris Grey

Slightly OT but where are people routing wiring for the roof lights??

Post #810245 14th Jan 2020 8:53pm
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topless_matt



Member Since: 29 Mar 2015
Location: norfolk
Posts: 65

England 2007 Defender 90 Puma 2.4 HT Tonga Green

Through the roof behind passenger side bulkhead. Down into the seat box where the relay is housed. Hold my beer and watch this!

Post #810253 14th Jan 2020 9:30pm
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90 Dreamer



Member Since: 13 Jul 2019
Location: Oop North
Posts: 1120

United Kingdom 2016 Defender 90 Puma 2.2 HT Corris Grey

As in physically drilling the roof or is there an alternative??

Post #810254 14th Jan 2020 9:31pm
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DSC-off



Member Since: 16 Oct 2014
Location: North East
Posts: 765

United Kingdom 2015 Defender 110 Puma 2.2 XS CSW Aintree Green

If there is a raised air intake fitted, the wires can exit the engine bay under the bonnet gap. Then run up the side of the snorkle. Some intake kits have facility to neatly run wires or breather pipes inside the snorkle.

Mud stuff have some shrouded cable glands that look an acceptable solution if the cable has to go through the roof.

Post #810278 14th Jan 2020 11:32pm
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donmacn



Member Since: 07 Nov 2017
Location: Nth Scotland
Posts: 1130

Mine are wired through the roof. If you do opt for that, rather than go to look at a 'car' accessory provider, I'd suggest having a good look at marine cable glands. I think the one I've got is "blue sea" but there will be others.

While a Defender roof will get wet, and deal routinely with 50-60mph 'winds', a marine fitting will be expected to deal with big lumps of water arriving with some force.

(Apologies to the OP - I hadn't appreciated that I was continuing the 'off topic' thing - though I hope it was useful!) Donald

1994 Defender 300Tdi 110 SW - owned since 2002 - 230k miles and going strong
(The 'rolling restoration' or tinkering thread: http://www.defender2.net/forum/topic58538.html)
2000 Range Rover P38 4.0L V8

in the past..
RR classic - fitted with 200Tdi
1984 RR classic - V8 with ZF auto box
1993 Discovery 300Tdi

not to mention the minis and the Type 2 VW camper...

Post #810281 14th Jan 2020 11:53pm
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Supacat



Member Since: 16 Oct 2012
Location: West Yorkshire
Posts: 8180

United Kingdom 2013 Defender 110 Puma 2.2 XS DCPU Keswick Green

DuncanS wrote:
Always assume the figures for wattage and current draw are garbage. Only very few manufacturers (Rigid, Laser etc) quote somewhat realistic figures rather than theoretical ones. I tend to use one of these for unknown circuit draws.LINK HERE although cheaper ones are available.


Missed your link first time of reading - that's a nice bit of kit:

Click image to enlarge


and rated to 80A according to the spec sheet.

I use a lowly TA123, only rated to 20A:

Post #810324 15th Jan 2020 11:02am
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BaronDefenders



Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 171

United Kingdom 2004 Defender 90 Td5 CSW Santorini Black

I shall see if I can get my hands on one of those!

And for the route question, my wiring goes between the windscreen frame and the door seal. 2004 Td5 90
2012 TDCi 110
1958 Series 2 88

Instagram: @BaronDefenders

Post #810334 15th Jan 2020 12:03pm
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hank



Member Since: 12 Sep 2016
Location: South Wales
Posts: 1210

Wales 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey

https://www.amazon.co.uk/Gunson-77068-Auto...B002WMYBS6 > 110 XS Double Cab
> Instagram @simonlanemind

Post #810335 15th Jan 2020 12:08pm
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Supacat



Member Since: 16 Oct 2012
Location: West Yorkshire
Posts: 8180

United Kingdom 2013 Defender 110 Puma 2.2 XS DCPU Keswick Green

BaronDefenders wrote:
And for the route question, my wiring goes between the windscreen frame and the door seal.


You could look to improve that with something like this:
https://www.12voltplanet.co.uk/scanstrut-h...ables.html


Click image to enlarge



But you could also say the way you have done it is the "official" way:

Click image to enlarge

Post #810352 15th Jan 2020 2:27pm
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DuncanS



Member Since: 07 Dec 2013
Location: Cumbria
Posts: 245

United Kingdom 2008 Defender 110 Puma 2.4 USW Santorini Black

Yep I have a scanstrut multiseal for the rear lightbar and rear roof accessories when I finally get round to fitting it. The front lightbar is going internally to the snorkel with some compression glands. North Cumbria Rescue & Response - Team Leader

Electrical Division @ K&S McKenzie Ltd, Carlisle

Post #810458 15th Jan 2020 9:48pm
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