Greeting, I am building an off grid cabins in the Colorado mountains. We are planning on wiring 24v for our lighting and have a large inverter to handle our needs AC well pump and 115/120 appliance needs. The concept here is we don't need to have the inverter turned on much of the time. My questions deals with low voltage wiring. I've done the normal AC wiring plenty of times but I am new to the DC wiring and I realize they are different beasts. 1. I notice that in the campers that have DC systems that many of the circuits are NOT wired in parallel. Can you not have 4 or 5 low draw amp led light appliances wired in parallel on a single circuit(So long as you don't exceeds the circuit capacity (breaker)? 2. I also noticed that there isn't a ground wire for these DC circuits. In wiring a home for 24v are you not required to have a ground wire on your circuit that leads back to your DC distribution panel? 3. In wiring DC circuits for a home are you required to place your wires in conduit? I ask this because I came across low voltage 14g bonded wire (much like romex but with twisted strains that) would make life simple. 4. Any good resources for wiring low voltage circuits? Thank you everyone in advance!!! Cheers Pete

A inverter might have 15 watts of loss and much less when it can go into standby mode. Probably not worth bothering with DC. Or consider a second small inverter just for lighting.

Yep, the newer good quality inverters have virtually no loss. On the other hand, the loss along that DC wiring is sure to disappoint. There's a good reason why DC lost the electricity war.

14 gauge wire is good for about 10 amps of 24V - depends on what % loss you can tolerate and how often a light will be used. So ~240 watts of 24V LEDs per wire.

When it comes to very long haul transmission, DC is winning.

I would also stick with AC wiring and lighting/appliances. The new inverters are pretty impressive with very low standby loads, yet still available for flip the light switch/instant lighting gratification Got an inverter or battery problem, a small generator will then be able to power all the circuits until you get the DC issue sorted. A good off-grid plan must be flexible...

IIRC the cutoff is 48V, anything below that is not considered to be dangerous, and there are really no standards for wiring it, hence the no ground or conduit required. That being said the problem is we use power, not voltage, and if the voltage is lower you end up using more current for a given amount of power, which requires a larger wire size to keep the line losses acceptable. You are also likely to need more runs (parallel) to keep the losses down. The problem with that is copper is expensive. The other issue is that low voltage loads (lights, appliances) are in much lower manufacturing volume, which means expensive. So your best bet from a cost standpoint is standard 120V wiring and loads, and just add an inverter between the battery and house. Solar power has driven the volume of the inverters up, and hence cost down. The inverters are also much more reliable then they once were. And since you are in Colorado you can do any work you want on your own property, and the permit is not very expensive, you just have to pass inspection. The only unknown is who does the inspection, some counties have their own inspectors, some have the state do it.

I suggest that < 48V is just as likely to start a fire as a higher voltage. But I'll agree that it's less of a shock hazard.

Perhaps more likely to start a fire with code having us put arc-sense breakers on most everything in living areas now, and the lack of uniform wiring standards for low voltage. Yes, my comment was for shock hazard.

Suggest change the design a little to allow your distribution system to use a DC water pump for submersible well pump. Use of DC for a pump reduces the overload capacity sizing and cost of the inverter. and allows use of your biggest - short term (less than a second) load at a higher efficiency. DC pumps naturally do a little better, and batteries easily. Most circuit breakers / switches are rated for AC, and low voltage DC currents. But can't have AC & DC in same panel. Good resource link: http://www.backwoodssolar.com/products/water-pumps/submersible-well-pumps/aquatec-swp-4000-submersible-pump

Just be aware that it might pump only 1 GPM @ 24V. And it has brushes that need relatively frequent maintenance. Using a Grundfos SQ pump (AC or DC) is common.

Higher cost / power / flow pumps are available.
anothr good link...
http://www.homepower.com/articles/solar-electricity/equipment-products/ask-experts-water-pumping
This link shows a brushless DC submersible. http://www.solar-store.com/cat%2012%20PUMPS.pdf
Gett what you pay for - little of this is high volume production, almost all special.