Low voltage only requirements in small cabin.

[fastline]

Doing work on a tiny cabin in which it will only be served with low voltage DC. The actual voltage has not yet been determined but the question is being asked how it should be wired? Most low voltage stuff has no listing so? Do we need NM wire? What about the lights?

The basic layout here is a single solar panel, to a charge controller, to a battery bank, and that bank supports the very basics like lights and a small electric water heater. I am still trying to find out if the AGM batteries will be required to be vented or be outside?

Also not sure of requirements for the charge controller? Being low voltage, does it still need UL? Our inspectors usually speak of their opinion rather than code requirement so I like to be sure.

 

[tthh]

Don't know. But, the AGM battery in my BMW is in the trunk and it has a vent tube to outside the trunk.

 

[tom baker]

Art 720 was for DC wiring on farms, but it was deleted in the recent code. I would wire with 14 awg, standard boxes etc, and find a unique dc receptacle. Then can be converted to AC 120. There are a lot of off grid cabins powered by solar, inverters and lithium batteries.

 

[hillbilly1]

A lot of people make the mistake of thinking small wire when talking low voltage, but remember, the lower the voltage, the higher the amperage for the same load. With the advent of LED lights, lighting is usually not an issue, but loads like refrigeration, if not gas, have a pretty heavy draw. Fans too.

 

[fastline]

I am mostly trying to figure out which codes that would apply whether that is NEC or back to IRC/IBC type stuff. I mean, build it clean and right, it will fly?

There is also the issue of components. 1 gang switches? Load center? Does seem like more AC gear is getting some sort of DC rating these days.

 

[retirede]

Many years ago, I helped a friend wire a cabin that was on an island in the middle of the Mississippi. We used automotive hardware. A fuse block that accepted AGC fuses and automotive wiring. He would charge a couple deep cycle batteries at home and take them to the island in his boat.
Of course, neither of us knew anything about codes back then.

 

[tthh]

A lot of people make the mistake of thinking small wire when talking low voltage, but remember, the lower the voltage, the higher the amperage for the same load. With the advent of LED lights, lighting is usually not an issue, but loads like refrigeration, if not gas, have a pretty heavy draw. Fans too.

Just do this.

You can't go wrong, the parts are easily available, it is mostly future proof and you know the rules that will make it work and safe.

As an example, I spent some time on a Hatteras motor yacht once...the thing has 120V/240V AC from a generator or shore power, but it also had 32V DC. All the 32V DC was run just like the the AC stuff on the boat.

 

[Joethemechanic]

Art 720 was for DC wiring on farms, but it was deleted in the recent code. I would wire with 14 awg, standard boxes etc, and find a unique dc receptacle. Then can be converted to AC 120. There are a lot of off grid cabins powered by solar, inverters and lithium batteries.

I've seen a lot of those 32 volt light plants at engine shows. A few old 32 volt wind generators too. What was the last code cycle that addressed them?

 

[tom baker]

That was Art 720, deleted in 20 or 23 NEC