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Looking for Electrical Advise

2K views 12 replies 4 participants last post by  C.J. Roberts 
#1 ·
Hello Everyone,

Attached if a schematic of wiring which I am planning for a 017 Willys Unlimited. I was wanting to ask for a few opinions on my plan,.... more specifically,

1. Do I really need a in-fuse between relay and power distribution block. In the distribution block there will be a fuse for each circuit.

2. 16 ga should be ok between switches and Relays??

3. I'm thinking I could also use 16 ga between relay and lights?

Thanks,
 

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#2 ·
Looks good to me. I would suggest one more fuse between the battery and fused distribution block to protect that particular wire run and a fuse on the power line feeding the switches. 16 gauge wire (stranded) can carry 10 amps. Saying that you can use a lighter gauge from your switches
to the relays. And with the listed amp draw from your lights it should be ok for the loads. Might want to do 14 gauge on the three light circuit. I assume most runs are fairly short- less than 10 feet. Be sure to select an automotive rated wire jacket that can handle moisture, oils, and temperature. Good luck
 
#4 ·
Shorter the better on the main power. With 12 volt systems, voltage drop is another issue you have to consider in addition to current carrying capacity. I worked in the automation field and with 120 and 24 volt circuits voltage drop wasn't as much of an issue. I would fuse that main line. Can't quite read your print, but I think you're planning on 8 gauge. I would fuse it at 40 amps. And I didn't realize you were pulling the switch power from another existing circuit. It would be safer directly from the battery with a fuse. Your jeep factory warranty would be protected that way
 
#6 ·
Sure. You can always go with a larger gauge (smaller AWG number). Only issue might be that it is more difficult to manipulate. Because you have it and it's such a short run it's crazy to spend money for new. Go for it. One thing you might check. Take a small sample and heat it up maybe with a hair dryer. Make sure the jackets doesn't get brittle. It will be warm under the hood.
 
#8 ·
Honestly, I think that you are going a little overboard here. The circuitry itself looks fine, but, IMHO, you're going larger than needed on wire size.
With exception to the main power and that 10 amp spare, you could easily get away with 18 gauge wire. Relays only use MAYBE a couple amps to power them, and your heaviest single circuit is only drawing 6 amps.
A 12 gauge wire would be more than adequate for your main, and that 10 amp spare could do with 16 gauge.
As a couple other posters have said, you can power everything directly from the battery.
 
#9 ·
C J
I can't argue your point except to say the automotive world seems to upsize wiring everywhere. Maybe because of temperature, moisture, abrasives ; I'm not sure but I'm constantly amazed at the wire size I see on purchased accessories. During my career we always figured 16 gauge could carry 10 amps and relay coil control current could easily be handled with 18, sometimes 20 gauge. I was only being cautious with my comments
 
#10 ·
No problem. If you want to use larger wiring, have at it. It certainly won't hurt anything.

I want pics when you get done. though.
 
#12 ·
https://www.wirebarn.com/Wire-Calculator-_ep_41.html

This is a handy tool for finding out what wire to use. Being a bit OCD about things, I like to use the thinnest wire possible for the job while still maintaining a decent factor of safety. I generally use a factor of safety of 2 for basic items. I bump it up to 5 if it is safety related.

Relay coils are very, very low wattage. They use such low current, like in the range of Milli-amps, that I have used cat-5 wire to run a series of them without any issue. Generally I pull the power for them from the fused power supply of whatever it is that they are switching. I also tend to ground-switch all my relays, so basically the switches in my cab just ground out the relay coil ground to activate. It makes it easier to only have to run one wire to the switch and reduces the risk of shorts. But that's just me.
 
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