What kind of wire for 12v house system

[Delos356]

Could anyone share the link to the type of wire they used for their house circuits? I got a 100 ft roll of 16 gauge "speaker wire" and wanted to make sure it was appropriate. I was going to do runs of this from each fuse to each switch. (Meaning each switch has it's own fuse) and then from the switch to the device regular 16 gauge wire, color coded. Then I can label the white jacket of the speaker wire with the appropriate color code? Am I on the right track?

I've done LOTS of house wiring but never worked with 12v so I want to check my plan before I go too wild.

https://www.amazon.com/dp/B001WHY3JO...roduct_details

[TheHubbardBus]

I'm sure when you were wiring houses you took into account the amperage of the circuit you were powering, the temperature rating of the wire your were using, and other applicable factors (running in conduit vs free air, environmental temperature, etc) to determine the appropriate wire gauge and type. DC is much the same. The main difference with 12VDC systems is voltage drop is a much greater concern, where in residential 120/240VAC wiring it's often not even considered, so your run length becomes a significant factor as well.

I'd find it surprising if every DC circuit in your bus was best served with 16 (awg?) gauge wire. And most speaker wire would not be appropriate for in-wall use, though with you mentioning a white jacket this may be the case (is it cl2/3 rated?). I also don't see why you'd have a switch for every circuit. No harm in it, I suppose, but for many circuits I don't see why you'd want one.

Here's a great (android) app that will do a lot of the math for you, so long as the parameters you input are correct. But I truly feel you'd be doing yourself a favor to study up more on the subject so you understand the reasons behind the tool's recommendations. Bear in mind distances are round trip (pos + negative), so if your appliances aren't chassis-grounded you'll generally double your run length for this input. Also bear in mind it assumes pure copper wire, not the CCA crap common with cheap wire off Amazon.

https://play.google.com/store/apps/d...hl=en_US&gl=US


NOTE: Just because it's DC & low-voltage doesn't mean it's not dangerous. If you overheat your wire, the insulation burns, which can start a fire, which can lead to a really crummy day.

[Delos356]

Okay that makes a lot of sense. This wire is copper, not CCA, and has a heat jacket and is rated for in wall use. It's really low resistance.
I'm trying not to chassis ground anything, all of it is going back to the bus bars. My longest run is a total of 30 feet. I'll definitely have a look at what the calculator says, thank you!

[TheHubbardBus]

Good call avoiding chassis grounds where you can.
With the price of wire these days, it helps to be precise. I'm thinking some of your circuits might likely require heavier than 16 (a distant water pump is one potential example), but many probably require less. If you can predetermine all your runs and plan ahead, you might save yourself some coin.

[Delos356]

Originally Posted by TheHubbardBus

I'm sure when you were wiring houses you took into account the amperage of the circuit you were powering, the temperature rating of the wire your were using, and other applicable factors (running in conduit vs free air, environmental temperature, etc) to determine the appropriate wire gauge and type. DC is much the same. The main difference with 12VDC systems is voltage drop is a much greater concern, where in residential 120/240VAC wiring it's often not even considered, so your run length becomes a significant factor as well.

I'd find it surprising if every DC circuit in your bus was best served with 16 (awg?) gauge wire. And most speaker wire would not be appropriate for in-wall use, though with you mentioning a white jacket this may be the case (is it cl2/3 rated?). I also don't see why you'd have a switch for every circuit. No harm in it, I suppose, but for many circuits I don't see why you'd want one.

Here's a great (android) app that will do a lot of the math for you, so long as the parameters you input are correct. But I truly feel you'd be doing yourself a favor to study up more on the subject so you understand the reasons behind the tool's recommendations. Bear in mind distances are round trip (pos + negative), so if your appliances aren't chassis-grounded you'll generally double your run length for this input. Also bear in mind it assumes pure copper wire, not the CCA crap common with cheap wire off Amazon.

https://play.google.com/store/apps/d...hl=en_US&gl=US


NOTE: Just because it's DC & low-voltage doesn't mean it's not dangerous. If you overheat your wire, the insulation burns, which can start a fire, which can lead to a really crummy day.

OKAY THAT APP IS AWESOME!!! Thank you so much! I ran through a few of my circuits and looks like either 16 or 18 would be okay. I think because they are all really low draw. Except my roof fan, it's recommending 12g for that run, unless I am calculating something wrong. 12g does seem like overkill...

[TheHubbardBus]

Isn't it? Yeah, I was familiar with their web chart but found it to be very limited / lacking in inputs. But that app is da bomb! Glad you found is as useful as we have!

If your inputs are all correct, I'd trust the 12awg recommendation. It does seem high on the surface, but I don't know anything about your specifics. Probably not ideal, but if was literally the only thing keeping you from using one size of wire (which might be the most cost-efficient option), you could replace each 12g wire with 2x16.

[john61ct]

Blue Sea Circuit Wizard for gauge sizing, round up.

Standardize on 3-4 sizes at most

UL1426 105c tinned "boat cable" type 3 fine stranded

proper crimping no solder

[Delos356]

Originally Posted by TheHubbardBus

Isn't it? Yeah, I was familiar with their web chart but found it to be very limited / lacking in inputs. But that app is da bomb! Glad you found is as useful as we have!

If your inputs are all correct, I'd trust the 12awg recommendation. It does seem high on the surface, but I don't know anything about your specifics. Probably not ideal, but if was literally the only thing keeping you from using one size of wire (which might be the most cost-efficient option), you could replace each 12g wire with 2x16.

I figured out what I was doing wrong with my input, and when I fixed it, the suggestion changed to 18. I had the allowable voltage drop set to 3% as if everything was a critical load.

Regarding keeping cost down, i have an almost infinity supply of 16 and 18g stranded copper wire so anything that falls in that realm under 10 feet long is free to me.

[TheHubbardBus]

Too cool. Glad that all worked out.
I wished I lived in your world of free copper
Best part is you came into this thread asking questions, and ended up answering them all yourself

[Delos356]

Originally Posted by TheHubbardBus

Too cool. Glad that all worked out.
I wished I lived in your world of free copper
Best part is you came into this thread asking questions, and ended up answering them all yourself

You guys are all just super good at educating people do they actually learn. Really appreciate all the help and guidance!

[HamSkoolie]

Originally Posted by TheHubbardBus

Good call avoiding chassis grounds where you can.
With the price of wire these days, it helps to be precise. I'm thinking some of your circuits might likely require heavier than 16 (a distant water pump is one potential example), but many probably require less. If you can predetermine all your runs and plan ahead, you might save yourself some coin.

I'm considering running two strands of the heavy copper wire they use with Sat dishes from the mains and down each side of my rig so that all grounds go to those wires (both of them) are used to secure the ground side of my circuits. Avoids chassis grounds and the price is right (lots of it hanging in my rafters, a gift from an installer who gave me a bunch).

I'm also considering running a VERY large positive circuit down one side of the bus and installing 3 or 4 separate fuse boxes for areas of the build to reduce the size of all the other wires needed for things.
And I may run a 110vac circuit to the HAM station area to run a 36 amp power supply at the 13.8 volts DC that HAM radios want. That will depend on where the HAM station ends up compared to the batteries. If it's a long run it will be AC if its short I'll just put a dedicated converter to 13.8vdc..

Decisions decisions......I've known what stuff I want in the rig for over a year but am just now starting to try to draw up the schematics and the actual location wiring diagrams.

[HamSkoolie]

Oh the circuit wizard app from Blue Sky is also on the Apple Store

[TheHubbardBus]

Originally Posted by HamSkoolie

I'm also considering running a VERY large positive circuit down one side of the bus and installing 3 or 4 separate fuse boxes for areas of the build to reduce the size of all the other wires needed for things.

That's pretty much what we're doing, just a smaller scale for a smaller bus. From the bulk of the electric system up front, we're running 6awg cabling to two separate DC panels, one on each side of the bus. That makes wiring for everything we need now, and may want later but don't yet know it, quick & easy.

[john61ct]

Originally Posted by HamSkoolie

Oh the circuit wizard app from Blue Sky is also on the Apple Store

Hopefully Blue Sea Systems BSS

[HamSkoolie]

Yep BLUE SEA
I'm a manned and unmanned pilot. Sky must have just automatically come out of my fingers.

[Polarweasel]

Book recommendation: Managing 12 Volts, by Harold Barre, has been helpful to me many times across several vehicles. You'll find the wire-sizing charts aren't super useful for very short wire runs, but overall it's a good (and short!) book.

Now I'm off to download the Blue Sea app.