Power to cargo area - what guage wire? (1 Viewer)

[CharlieS]

I've tried to search, and it looks like 10ga is a common choice.

I'm putting a six fuse blue sea distribution panel in back with a 125 amp blue sea circuit breaker in the engine compartment off the auxiliary battery.

I don't know what loads I'll be putting on it. I'm definitley rewiring my national Luna led hatch light to it. I might put some usb plugs for device charging and an auxiliary jack (used to call them cigar/cigarette lighters). I may (on rare occasion) plug in an electric refrigerator. I'm tempted to install some switched under vehicle "Rock lights" under the rear bumper like on the Slee heritage edition.

Any guidance?

 

[tincan45]

I've tried to search, and it looks like 10ga is a common choice.

I'm putting a six fuse blue sea distribution panel in back with a 125 amp blue sea circuit breaker in the engine compartment off the auxiliary battery.

I don't know what loads I'll be putting on it. I'm definitley rewiring my national Luna led hatch light to it. I might put some usb plugs for device charging and an auxiliary jack (used to call them cigar/cigarette lighters). I may (on rare occasion) plug in an electric refrigerator. I'm tempted to install some switched under vehicle "Rock lights" under the rear bumper like on the Slee heritage edition.

Any guidance?

Hey @CharlieS - I just got a 6 AWG back there today. See Post:

Non-traditional DC power system build

Hi Folks, With a nice long weekend and no real plans, I was able to start on my DC charging and power system. I'll start with the disclaimer that this is a work in progress, and while it all works "in my head", I'm sure I'll encounter a few surprises along the way. This is a bit of a departure...

forum.ih8mud.com

 

[grinchy]

Part 1: Choosing the Correct Wire Size for a DC Circuit - Blue Sea Systems

Engineering high quality marine electrical components for safety, reliability and performance

www.bluesea.com

i ran 4 gauge to the driver location for an amp replace. Then 8 gauge to the back corner. Maybe should have run 4 gauge back. I think 4 gauge a good bet for almost all uses.

 

[grinchy]

I’ll also recommend Knuconceptz wire. It is very flexible and not expensive in the grand scheme. They also have terminals and distribution blocks.
the last couple stinger products I tried were also good, but the knuconceptz was better.

stick with copper not cca.

 

[Bunga]

My preference is 8 ga for a nominal 10 foot run, uses standard ends, small enough to manage, big enough not to lead to a lot of voltage drop. I use these or their trailer wire. Double Conductor Wire | Polar Wire

 

[RiDE]

I ran 4g up the driver side to a fuse block behind the pop out panel. Makes it easy to access fuses and install other accessories I may need in the future.

 

[96bruizer]

Ive done the same thing. Blue sea box in the rear, powers lights and my fridge, etc... I ran a 6ga wire from the battery With 125amp fuse.

 

[mcgaskins]

There's a lot going on in this post, but I used 6 gauge Ancor Marine duplex wire with a Blue Sea fuse box which worked great:

Builds - mcgaskins' 2016 build thread - Ruby

As some of you may know, I had a 2014 that was built in the past, but I really liked the 2016 refresh and wanted to give the 8 speed a try to see if it worked better off road. Some pics of the 14: I found a decent deal on a 2016 in brandywine/terra in Minnesota and had it shipped to...

forum.ih8mud.com

 

[Ratchey]

I also recommend 4 ga. It's a bit difficult through the B-Pillar but you won't want for power if you add stereo and fridge and other items...

 

[KLF]

I'm putting a six fuse blue sea distribution panel in back with a 125 amp blue sea circuit breaker in the engine compartment off the auxiliary battery.

Big rule when doing any electrical circuits: the protection device (fuse, circuit breaker) needs to be the WEAKEST part of the system. So, if you are feeding this line with a 125A breaker, you need a HUGE wire, like a #2 or larger. Worst case scenario: if you ran a #10 wire back and had a significant fault to ground, the short could be pulling 124.9 Amps and the breaker would not do anything. But, the wire would melt away and could burn your truck to the ground.

I would start with a smaller breaker at the battery. I have a 100A breaker, then I ran #4 to the Blue Sea panel bolted to the back of my ARB drawers.

 

[sdnative]

Are you going to run a positive and negative? That is what I would do but there are (strong) opinions either way. I wouldn't rely on the body as a return conductor due to the way the various body panels are patched together. If you don't run a negative cable, I would use the frame as a return. On my last truck I ran a 4ga positive through the firewall and back to the cargo area in the PS door sill. I ran a 4ga from the cargo area down to the frame, then another 4ga or 6ga from the frame to the battery.

 

[sdnative]

Big rule when doing any electrical circuits: the protection device (fuse, circuit breaker) needs to be the WEAKEST part of the system. So, if you are feeding this line with a 125A breaker, you need a HUGE wire, like a #2 or larger. Worst case scenario: if you ran a #10 wire back and had a significant fault to ground, the short could be pulling 124.9 Amps and the breaker would not do anything. But, the wire would melt away and could burn your truck to the ground.

Yes, very true. The OCPD is to protect the wiring.

Circuit breakers are convenient because they can be reset. But the rating is not a fixed value when they will trip. Circuit breakers have a trip curve that is a relationship between current and time. It's not unusual for a CB to pass several times the rated current for several seconds. Just something to keep in mind when sizing CB and cables.

 

[LBridges]

What @KLF said.

Below is a table that has maximum fuse sizes for the various gauges of wire. You can always use a lower rated fuse, but not higher (general rule of thumb - to be safe the fuse/circuit breaker should be within 18 inches of the battery/source).

One more point. on average a 10 gauge wire will lose about 1/2 Volt compared to a 4 gauge over say a 15 foot run. These numbers are an approximation. To get real numbers you need real load and do a search for dc voltage drop calculator. If you load is not voltage sensitive then maybe this isn't as important.

Wire Gauge​	Recommended Maximum Fuse Size​
00 awg​	400 amps​
0 awg​	325 amps​
1 awg​	250 amps​
2 awg​	200 amps​
4 awg​	125 amps​
6 awg​	80 amps​
8 awg​	50 amps​
10 awg​	30 amps​
12 awg​	20 amps​
14 awg​	15 amps​
16 awg​	7.5 amps​

 

[TeCKis300]

My go to is 4 gauge for any trunk wire. One could get away with less, but it's incrementally more cost and same effort. Allows for future expansion without duplicating effort.

With any trunk wire that's meant to carry good current, make sure you buy pure copper. Lots of stuff out there is copper clad aluminum. If it's cheaper for a given gauge, that's a giveaway that it's CCA. Nothing wrong with it for smaller gauge stuff, but one will need up upsize the wire for the same power handling. It also is known to contract and expand more with heat, which is why I say not to use it for true current handling as junctions can loosen up and build up resistance over time.

 

[Sandroad]

And for those that want to delve into the minutiae, there is a lot of info to be had from the boating and RV worlds. And one relevant point on wire runs.....in DC circuits it’s the round trip that counts, not one way.

Part 2: Select a Fuse and Fuse Holder For Your DC Product Installation - Blue Sea Systems

Engineering high quality marine electrical components for safety, reliability and performance

www.bluesea.com

Part 1: Choosing the Correct Wire Size for a DC Circuit - Blue Sea Systems

Engineering high quality marine electrical components for safety, reliability and performance

www.bluesea.com

 

[Markuson]

Just sofolks know it can be done...
-I ran TWO massive 1-Guage wires all the way back on driver...to replace the single 4-gauge wire I had...through impossibly small spaces...from engine bay...driver firewall...under both door jams an md to the back...in **addition to other wires I had already added.

This solvedavoltage drop issue I had that will rarely apply to most.
It worked, so was worth it for me. Extreme overkill for most others.

 

[CharlieS]

Big rule when doing any electrical circuits: the protection device (fuse, circuit breaker) needs to be the WEAKEST part of the system. So, if you are feeding this line with a 125A breaker, you need a HUGE wire, like a #2 or larger. Worst case scenario: if you ran a #10 wire back and had a significant fault to ground, the short could be pulling 124.9 Amps and the breaker would not do anything. But, the wire would melt away and could burn your truck to the ground.

I would start with a smaller breaker at the battery. I have a 100A breaker, then I ran #4 to the Blue Sea panel bolted to the back of my ARB drawers.

View attachment 2319140

Thank you! I'll get a smaller circuit breaker.

 

[CharlieS]

Are you going to run a positive and negative? That is what I would do but there are (strong) opinions either way. I wouldn't rely on the body as a return conductor due to the way the various body panels are patched together. If you don't run a negative cable, I would use the frame as a return. On my last truck I ran a 4ga positive through the firewall and back to the cargo area in the PS door sill. I ran a 4ga from the cargo area down to the frame, then another 4ga or 6ga from the frame to the battery.

Yes, I was going to run two wires of the same size.

 

[CharlieS]

Just sofolks know it can be done...
-I ran TWO massive 1-Guage wires all the way back on driver...to replace the single 4-gauge wire I had...through impossibly small spaces...from engine bay...driver firewall...under both door jams an md to the back...in **addition to other wires I had already added.

This solvedavoltage drop issue I had that will rarely apply to most.
It worked, so was worth it for me. Extreme overkill for most others.

How did you get those wires through the firewall? That's my next challenge. I've already used up three of the four (nipples) in the grommets on the large circular firewall plugs. I don't think I can fit two large wires through the one I have free.

 

[grinchy]

How did you get those wires through the firewall? That's my next challenge. I've already used up three of the four (nipples) in the grommets on the large circular firewall plugs. I don't think I can fit two large wires through the one I have free.

The grommets are filled with a foam substance and seal pretty good when used the old fashioned way (poke a hole). I used a lathe chisel to create the hole, then fished with that.

Another option is to run under the car (the pathway behind the heat shielding is pretty easy to follow) and then run up thru the grommet at the left rear or right rear. Those aren't as fancy as the firewall grommets, but are also not as crowded. Simple cut and then reseal if necessary with Sugru.