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Electrical / Radios Discussion of electrical systems and accessories.

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  #1  
Old 16-10-17
BeanCounter BeanCounter is offline
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Join Date: Mar 2012
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Default Trailer wire for worklights

Ok, so planning to put some lights up on my roof rack. Be 18w led bars, two at the rear and possibly one pointed to each side of the car. So 4 in total. Looking at how to run the wiring I am thinking I could use a 5 core trailer wire, treat 4 wires as a positive, and the 5th as a common earth coming back to the battery.

So if my calculations are correct (I am an accountant so *of course they are correct*) 18w will pull 1.5 amps.

Supercrap have 5 core they say is 15amp, yet the narva is only rated at 5amp. Either way would there be an issue using trailer wire? I'm thinking it allows me only to have to run one small cable to the roof, which I can split off against each light. At the battery end I will wire in individual switches then wire to the second battery (fused of course, possibly 5amp fuse each depending on which wire I get)

Thoughts? Possible? Issues? Alternative options?
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  #2  
Old 16-10-17
chrisall chrisall is offline
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Sounds reasonable, the 5 core cable can carry 5A per circuit and as you say 18w @ 12v is 1.5A each.

Only difference I would do is omit the common earth back to the battery, and earth through the body instead. Perhaps leave the 5th core as a spare in case you want to add anything else at a later date.
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  #3  
Old 17-10-17
erad erad is offline
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You are looking to have 4 x 18 W lights. That is a total of 6 amps. Having one wire going to each lamp is fine (1.5 amps each), but the current still has to return down the earth wire, so you will have 6 amps going back to the plug. That is a bit heavy for trailer wiring and you will get a lot more voltage drop. The lights will still work, but not quite as bright. You probably won't notice the difference. Check the earth wire to see that it doesn't get too hot.
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  #4  
Old 17-10-17
zoiks zoiks is offline
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Quote:
Originally Posted by BeanCounter View Post
Ok, so planning to put some lights up on my roof rack. Be 18w led bars, two at the rear and possibly one pointed to each side of the car. So 4 in total. Looking at how to run the wiring I am thinking I could use a 5 core trailer wire, treat 4 wires as a positive, and the 5th as a common earth coming back to the battery.

So if my calculations are correct (I am an accountant so *of course they are correct*) 18w will pull 1.5 amps.

Supercrap have 5 core they say is 15amp, yet the narva is only rated at 5amp. Either way would there be an issue using trailer wire? I'm thinking it allows me only to have to run one small cable to the roof, which I can split off against each light. At the battery end I will wire in individual switches then wire to the second battery (fused of course, possibly 5amp fuse each depending on which wire I get)

Thoughts? Possible? Issues? Alternative options?
Depending on the lights that you have, you "may" run into voltage drop issues. Unlikely though as a lot are rated for like 9-36V.

Note: These are my own calcs using formulae from my own research. I suggest your double check it all

Assumptions:
  • 4x devices @ 18w each
  • 1x common ground
  • 6m total wire length (from battery to devices and back to battery)
  • Non critical device so allow for 10% voltage drop over wire
  • Your wire looks like it is AWG20ish

Doing some quick calcs using your 18w power usage.
18w @ 12V = 1.5A; Common ground will be 4x1.5A = 6A so lets focus on that.
12V @6A allowing for 10% is ok for 6.5M loop

Temp rating wise, 20AWG in a 4-6 conductor bundle travelling through your engine bay allows for 7amps.

So voltage drop and temperature should should both be ok.

Personally I would see if you can jump up a size if you are thinking of running all lights for extended periods of time.
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  #5  
Old 17-10-17
Morville Morville is offline
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Why not buy 7 core trailer wire and run 2 as earth or with 1 earth wire for 2 lights, still with one spare wire.
Peter
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  #6  
Old 17-10-17
BeanCounter BeanCounter is offline
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Join Date: Mar 2012
Location: Tasmania
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Quote:
Originally Posted by zoiks View Post
Depending on the lights that you have, you "may" run into voltage drop issues. Unlikely though as a lot are rated for like 9-36V.

Note: These are my own calcs using formulae from my own research. I suggest your double check it all

Assumptions:
  • 4x devices @ 18w each
  • 1x common ground
  • 6m total wire length (from battery to devices and back to battery)
  • Non critical device so allow for 10% voltage drop over wire
  • Your wire looks like it is AWG20ish

Doing some quick calcs using your 18w power usage.
18w @ 12V = 1.5A; Common ground will be 4x1.5A = 6A so lets focus on that.
12V @6A allowing for 10% is ok for 6.5M loop

Temp rating wise, 20AWG in a 4-6 conductor bundle travelling through your engine bay allows for 7amps.

So voltage drop and temperature should should both be ok.

Personally I would see if you can jump up a size if you are thinking of running all lights for extended periods of time.
That is now what I am thinking. Supercheap have 15amp trailer wire, however last time I used their trailer wire it was basically 5 wires dipped in liquid rubber and set - made splicing individual wires or stripping very hard, whereas in comparison something like the Narva seems to have a plastic wrap around the core wires before the outer, hence very easy to work with.

I might hunt around for better quality 15amp trailer wire. Narva website say they make it, just need to find it (ah the perks of living in Tasmania, buying retail is so easy, they only stock one of anything - no decisions to be made).
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  #7  
Old 18-10-17
erad erad is offline
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Join Date: Mar 2015
Location: Cooma NSW
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Further to my posting above, if you are only using 1 worklight at a time, voltage drop on the earth return wire should be minimal. In any event, the LED light will work over a wide range of voltages, so this should not be an issue.
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  #8  
Old 18-10-17
Apollo Apollo is offline
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Join Date: Dec 2016
Location: Cooloola Coast QLD
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Quote:
Originally Posted by BeanCounter View Post
...... (ah the perks of living in Tasmania, buying retail is so easy, they only stock one of anything - no decisions to be made).
The ALDI of Australian states?
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  #9  
Old 18-10-17
craka craka is offline
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Join Date: Jun 2009
Location: Newcastle (Newie)
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Quote:
Originally Posted by BeanCounter View Post
(ah the perks of living in Tasmania, buying retail is so easy, they only stock one of anything - no decisions to be made).
Quote:
Originally Posted by Apollo View Post
The ALDI of Australian states?

Ah love it!

I am yet to visit Tassie, but those kind of statements make me think is a pretty relaxed place to live.
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  #10  
Old 4 Weeks Ago
Racer17 Racer17 is offline
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https://www.autobarn.com.au/narva-ca...a-100m-el08766
https://www.autobarn.com.au/narva-ca...p-30-5853-30tc
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