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BaronDefenders



Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 99

United Kingdom 2004 Defender 90 Td5 CSW Santorini Black
Light Bar Fuse Melting

I’ve been out and about in Yorkshire this weekend and have been making use of the collapsed star fitted to the 90’s roof. However, I was noticing a smell of very hot electrics/plastic. Eventually the light bar cut out. After a quick look in the fuse panel, the 15A fuse had melted. I have limited knowledge on electrickery. It’s not my forte. Does anyone have an idea as to why the fuse would melt? I don’t want to just slap a bigger fuse in if there’s a problem hiding. The light bar is stated to have a current draw of 12A at 24v.

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 2004 Td5 90
2012 TDCi 110
1958 Series 2 88

Instagram: @BaronDefenders

Post #810131 13th Jan 2020 9:17pm
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topless_matt



Member Since: 29 Mar 2015
Location: norfolk
Posts: 42

England 2007 Defender 90 Puma 2.4 HT Tonga Green

Sounds like there is a short somewhere in the circuit. Is there any condensation or moisture in the lightbar? Hold my beer and watch this!

Post #810132 13th Jan 2020 9:21pm
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UtilityTruck



Member Since: 09 Jan 2014
Location: Oxford
Posts: 364

United Kingdom 

Is it definitely 12A at 24V? If so, that’s 24A at 12V.

If it’s 12A at 12V, your fuse could be a little bigger and still be safe.. try 18A. 2014 Keswick Utility 2.2

Post #810134 13th Jan 2020 9:28pm
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BaronDefenders



Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 99

United Kingdom 2004 Defender 90 Td5 CSW Santorini Black

I did wonder if there was a short but it was professionally installed not long ago. No condensation in the bar.

Yes it’s quoted as 12A at 24V. OK then, I’ll try an 18A and see how that goes! 2004 Td5 90
2012 TDCi 110
1958 Series 2 88

Instagram: @BaronDefenders

Post #810136 13th Jan 2020 9:39pm
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UtilityTruck



Member Since: 09 Jan 2014
Location: Oxford
Posts: 364

United Kingdom 

If it’s rated 12A @ 24V then it will draw 24A on a 12V system like the defender, so you’ll need a much bigger fuse plus make sure your wiring and relay are up to the job, I know you said it was professionally installed but if they fitted a 15A fuse I’d be getting a second opinion on the whole install. Smile 2014 Keswick Utility 2.2

Post #810141 13th Jan 2020 10:00pm
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BaronDefenders



Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 99

United Kingdom 2004 Defender 90 Td5 CSW Santorini Black

OK thanks. It seems like the fuse is probably far too small for the light bar. It’s a Mobile Centre harness that I had made up so it should be good quality. I think I’ll start by going up to a 20A fuse and see how that fares. Thumbs Up 2004 Td5 90
2012 TDCi 110
1958 Series 2 88

Instagram: @BaronDefenders

Post #810142 13th Jan 2020 10:22pm
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bankz5152



Member Since: 02 Feb 2017
Location: South London/North Kent
Posts: 1537

2004 Defender 110 Td5 DCPU Epsom Green

30 amp fuse. Instagram @defender_ventures

Post #810154 14th Jan 2020 6:16am
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topless_matt



Member Since: 29 Mar 2015
Location: norfolk
Posts: 42

England 2007 Defender 90 Puma 2.4 HT Tonga Green

topless_matt wrote:
Sounds like there is a short somewhere in the circuit. Is there any condensation or moisture in the lightbar?

Sorry misread the 24v part. As above needs a suitable fuse as the 15 is very under rated. However as above I would check the whole install if it was supplied fitted with a 15 amp fuse. Hold my beer and watch this!

Post #810163 14th Jan 2020 7:01am
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Bluest



Member Since: 23 Apr 2016
Location: Lancashire
Posts: 2112

United Kingdom 2007 Defender 110 Puma 2.4 XS CSW Java Black

What light bar have you got? Must be like staring into the sun. 2007 110 TDCi Station Wagon XS

Post #810167 14th Jan 2020 7:23am
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BaronDefenders



Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 99

United Kingdom 2004 Defender 90 Td5 CSW Santorini Black

OK, seems the general consensus is that the fuse is too small. I’ll have a quick check over all of the wiring.

It’s a GRP 54” light bar. It’s good for illuminating pretty much everything and also for burning out the eyes of oncoming motorists. Whistle 2004 Td5 90
2012 TDCi 110
1958 Series 2 88

Instagram: @BaronDefenders

Post #810174 14th Jan 2020 8:10am
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grafty99



Member Since: 15 Aug 2012
Location: North Devon
Posts: 4308

United Kingdom 2002 Defender 90 Td5 HT Caledonian Blue

If it came fitted with a 15A fuse then the whole loom might not be rated for the current you'll be pulling through it. If you put a big amp fuse in wiring that isn't designed for it then the wiring becomes the fuse.

Things then start getting messy Shocked 2002 90 Td5 Station Wagon
1990 Vogue SE
Triumph Tiger Explorer 1200
Td5 90 Thread http://www.defender2.net/forum/topic50767.html
Tdi 110 Thread https://www.defender2.net/forum/topic69562.html
RRC Thread http://www.defender2.net/forum/topic54492.html
Instagram http://www.instagram.com/george_grafton

Post #810175 14th Jan 2020 8:19am
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BaronDefenders



Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 99

United Kingdom 2004 Defender 90 Td5 CSW Santorini Black

That is a concern . . . I’ve sent Mobile Centre an email asking what the whole harness is rated to. 2004 Td5 90
2012 TDCi 110
1958 Series 2 88

Instagram: @BaronDefenders

Post #810177 14th Jan 2020 8:29am
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DuncanS



Member Since: 06 Dec 2013
Location: Cumbria
Posts: 216

United Kingdom 2008 Defender 110 Puma 2.4 USW Santorini Black

Be aware a blade fuse only blows at DOUBLE the rating on the fuse, so your 15a will only blow completely at 30a, which is why it was starting to go. Always ensure that the cable is rated for more than the face value figure of the fuse, and try and keep that fuse rating as close to the current draw of that circuit. You will find that any good quality automotive cable will handle spike loads of double the normal rating for five seconds or less, and after that point the fuse blows anyway. CU040 - Cumbria 4x4 Response
Electrical Division @ K&S McKenzie, Carlisle

Post #810180 14th Jan 2020 8:59am
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BaronDefenders



Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 99

United Kingdom 2004 Defender 90 Td5 CSW Santorini Black

I think I need to wait and see what Mobile Centre have to say about the harness. Once I’ve had that info I can look to swap the fuse or the whole harness. But it’s clear now that a 15A fuse is too small. 2004 Td5 90
2012 TDCi 110
1958 Series 2 88

Instagram: @BaronDefenders

Post #810183 14th Jan 2020 9:27am
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BaronDefenders



Member Since: 28 Jun 2019
Location: London/Cotswolds
Posts: 99

United Kingdom 2004 Defender 90 Td5 CSW Santorini Black

I’ve just been on the phone with Mobile Centre who are going to make me a new harness. They’ve said that the harness is being overloaded and hence the fuse is melting and not blowing. The harness I currently have is rated to 15A. The GRP 4x4 light bar is probably drawing about 42A. GRP told me it draws 4A in an email whilst they quote 24A on their website but the figures for Wattage make a figure of around 42A. 2004 Td5 90
2012 TDCi 110
1958 Series 2 88

Instagram: @BaronDefenders

Post #810191 14th Jan 2020 11:08am
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