Wire and Fuse Size Check

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Ikigai

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Hi,

I was wondering if anyone could take a look at my wire and fuse/cb sizes and make sure nothing looks really off?  Depending on which website/chart I used I got wire sizes from 6 to 14 AWG on the same item, so I'm really unsure about this.  Thanks!

Component  --- Wire Length [font=Tahoma, Verdana, Arial, sans-serif]--- [/font]AWG[font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size] Fuse/CB
DC-DC Charger (30A) to CCP (Van Battery) [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]15' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]6 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]50A
DC-DC Charger (30A) to Battery Bus [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]2' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]---[/font][/size][/font][/size] 8 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]50A
MPPT (30 Amps) to Solar Panel (175 W) [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]25' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]8 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]50A
MPPT (30 Amps) to Battery Bus [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]2' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]8 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]50A
Charge Converter (25 Amps) to Battery Bus [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]3' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]Included[font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size] 30A (35A internal)
Battery (100 Ah, 12V) to Battery Bus [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]3' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]2 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]100A
Battery Bus to Fuse Box/CB Panel [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]3' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]2 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]100A
Fuse Box/CB Panel to Auxiliaries [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]<25' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]10 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]<=15 amps

Back to negative same size and length
Battery Monitor attached in line between negative bus bar and negative battery post
 
All looks good to me. On those 8awg wires, I might put in 40a protection instead of 50a.
 
The large disparity in wire size might be the double in length factor. I notice some online charts allow for this and some don't. Did you take that into consideration? In other words with DC circuit you must count the total length both ways. For instance if your radio is 4 feet from your battery the total length is 8 feet not 4. Highdesertranger
 
PlethoraofGuns  -Thanks, good idea on the 50 to 40 amps.  

highdesertranger -The lengths I listed and used are just in one direction, although the DC-DC Charger (30A) to CCP (Van Battery) doesn't have a ground wire between (the charger is grounded).
 
Yeah you need to count both ways for the length even if you are using the chassis for ground. Highdesertranger
 
Ikigai said:
Hi,

I was wondering if anyone could take a look at my wire and fuse/cb sizes and make sure nothing looks really off?  Depending on which website/chart I used I got wire sizes from 6 to 14 AWG on the same item, so I'm really unsure about this.  Thanks!

Component  --- Wire Length [font=Tahoma, Verdana, Arial, sans-serif]--- [/font]AWG[font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size] Fuse/CB
DC-DC Charger (30A) to CCP (Van Battery) [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]15' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]6 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]50A
DC-DC Charger (30A) to Battery Bus [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]2' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]---[/font][/size][/font][/size] 8 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]50A
MPPT (30 Amps) to Solar Panel (175 W) [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]25' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]8 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]50A
MPPT (30 Amps) to Battery Bus [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]2' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]8 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]50A
Charge Converter (25 Amps) to Battery Bus [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]3' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]Included[font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size] 30A (35A internal)
Battery (100 Ah, 12V) to Battery Bus [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]3' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]2 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]100A
Battery Bus to Fuse Box/CB Panel [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]3' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]2 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]100A
Fuse Box/CB Panel to Auxiliaries [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]<25' [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]10 [font=Tahoma, Verdana, Arial, sans-serif][size=small][size=small][font=Tahoma, Verdana, Arial, sans-serif]--- [/font][/size][/font][/size]<=15 amps

Back to negative same size and length
Battery Monitor attached in line between negative bus bar and negative battery post
Click to expand...
This is knowledge I will be needing soon.. electrical has always confused me  :-/ :-/
 
The size of the fuse depends on the class and size of the wire or cable. I use marine grade stranded wire with insulation rated at 105 C. If the wires are not bundled, 6 AWG gets a 100 to 120 amp fuse. 8 AWG gets 70 to 80 amp fuse. There are two criteria for selecting fuse size. The ampacity of the wire and a consideration of voltage drop. As fuses protect wire, I can use the larger fuse appropriate to the wire. The larger fuse has lower voltage drop than a smaller fuse at any given current flow.
 
What happens when you draw 110a through that 6awg with a 120a fuse?
 
^^^I simplify everything by over building and making DC circuits as short as possible. It costs a little more and adds a little weight but I don't have to worry as much about burning stuff up if I add something later or have a problem. Remember fuses protect the wire. My guess is it gets warm and heat cycles cause problems, but what do I know! LOL!!!
 
Would highly suggest you use a Ground wire instead of the chassis. Just my 2 cents worth.

Mike R
 
Mike, 

What do you mean by use a "ground wire instead of the chassis?"

I was planning on routing everything back to the negative bus bar, and then attach that to the negative of the battery and the chassis.  Although I'm not sure how the chassis connection works.  Do you recommend something different?
 
It's common to to attach the negative post wire from the battery right to the body of the vehicle. Then all your 12v electrical component grounds go to the body ASAP, thus making the body part of the circuit. I did that with my van body, but it is all aluminum, which is a good conductor of electricity. Steel is not the best conductor, but will work. You need to make sure your ground connections to your body are super crazy good. Like grinded down and using dielectric grease kinda good. And if circuit flows from body to chassis or vice versa, one will surely need to upgrade that ground wire too as the stock one was never designed to carry the electrical loads you'll be adding to it.

The other way which is the better way is to run individual wires from your electronic components right back to the battery. Yes, have a bus bar for all those wires to attach to, but wires to and from everything, not going through the body.
 
Thanks PlethoraOfGuns, if I run everything back to the battery do I still need to run one wire to the chassis as ground?
 
Looks like I need a ground to chassis regardless because I got the non-isolated B2B.  So complicated!!
 
PlethoraOfGuns said:
What happens when you draw 110a through that 6awg with a 120a fuse?
Click to expand...
If the wire is not in an engine room, it can carry 110 amps all day long. Pf it is in the engine room I fuse it with 100 amp fuse. I would check voltage drop before I chose 6 awg, I may need 4awg or more.
 
Ah yes, the non isolated battery charger might require a chassis-body wire upgrade. Depends, as you need to check how and what size ground wire is at the starter battery.

I'd be careful running 110a through that wire. It is not rated to carry that much power. Fuses protect wire from both shorts and overload situations so you don't melt your insulation.
 
PlethoraOfGuns,

My isolator is only 30 amps, with a 50 amp cb so it should be good in that regard.
 
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