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Littlecooner
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# Posted: 20 Jun 2016 07:44pm - Edited by: Littlecooner
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I have been blown away by the knowledge that exist on this forum. Therefore, I need help. A great do it yourself er, I wander thru a lot of stuff and design and just do, but the electricity is a bummer.
The crazy redneck cabin in the mountains is 12x20. I am fortunate that it is a 15 minute run by ATV or 4 wheel drive vehicle from the primary residence, so it will be the weekend place, the hunting shack, the few days away place, etc. It is now time to move inside and finish this project.
One item that is a definite item is the 12, 24, 48 volt ceiling fan. I have a "wet weather spring" for winter time water and hope to install a micro hydro generator in the end for electricity. Cabin is "in the woods" so solar is not an option.
Now for the question, way to much information on the internet, dang Al Gore for inventing this technology. HELP - I have decided to wire the north wall (20') for 110, put in a breaker box, etc and wire to run a gas powdered generator for lights, winter heat, etc. Then I am going to wire the south wall for 12 volt, to run the 12 volt RV LED lights in the sleeping part of the cabin, the ceiling fan and some lights and recharging stations in the kitchen part of the cabin. This one roll of 250' of 14 Gage romex will handle it all. Some of you experts, and I now understand you are here and really understand this stuff, tell me if it is ok to use the 110/220 romex to wire ( solid copper wire) in for the lights and the ceiling fan or do I need to go purchase some stranded 10 or 12 gauge wire for this wiring. lights will be 30 feet max round trip to battery supply, fan will be 20 feet and the kitchen "stuff" will be 5-10 feet.
Thanks for the information.
Here is the specs for the fan. Lucky to live less that an hour of travel to one of the guys who sell this product.
3-Blade Vari-Cyclone Specifications
Blade swing: 60 inches (1.52 m) diameter
Weight of fan: 14 pounds (6.35 kg)
Shipping weight: 17 pounds (7.7 kg)
Amps: 0.5 @ 12 VDC
0.78 @ 24 VDC
Watts: 2 @ 9 VDC
4 @ 12 VDC
13 @ 24 VDC
RPM: 75 @ 9 VDC
102 @ 12 VDC
138 @ 24 VDC
CFM: 852 @ 9 VDC
1,476 @12 VDC
3,925 @ 24 VDC
Really like the looks of that new 24 volt battery in the other new thread. Technology moves on and it could be an option for the new system I hope to install next year.
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bldginsp
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# Posted: 20 Jun 2016 09:37pm - Edited by: bldginsp
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Wire size is entirely a function of amperage, regardless of voltage. 14 gauge wire should not be asked to handle more than 15 amps, and should always have a 15 amp breaker ahead of it. Put the fan on a separate circuit and breaker with nothing else. With the low amperage rating of the fan this is not absolutely necessary, but if you switch the fan you need a separate switch wire.
The distances you are talking about are very short and will cause no problems with voltage drop.
Your #14 wire won't handle much in the way of electric heating, though. Do you have specs on your elec heater?
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Asher
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# Posted: 21 Jun 2016 08:09am
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WARNING: The following response is from someone that is not a professional or a electrical engineer.. Just someone that has done a lot of electrical work on high drain 12v systems and burnt up a lot of wires along the way learning... 
Don't use solid wire for 12v systems, electrical current is carried along the surface of the wire not the inside, that's why heavy amp draw wiring use multi-strand wiring, the more strands the better the current carrying surfaces without heating up.
If I was wiring up a 12v system, I would use a auto/marine fuse panel located close to the batteries, then run some multi strand wire to your outlets. If you need switches then run the wire to the switch box and place a high cap relay inside the box, the relay will keep the amps from burning up the switch. Also remember that small gauge wire, long runs, and heat create lost energy so if you have long runs, step your wire size.
I am guessing your looking a single strand because of cost, if that's the case and your amp draw and runs are low/short, then look at trailer wiring kits... around here you can get a 12g 4 wire 25' ish trailer kit for cheap..
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razmichael
Member
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# Posted: 21 Jun 2016 10:06am
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Skin effect is an AC thing only with only minimal impact at lower frequencies. Stranded wiring is used in marine, RV applications primarily as it has more flexibility and easier to terminate for heavier gauge. IMO also, the use of standard AC toggle switches for DC is fine for small loads - couple of LED lights. The risk of arcing and fuzing the switch is minimal. I used standard 20 amp toggle switches and have seen no sign of arcing. Even if it did ruin the switch in 5 or ten years - cheap to replace.
By the way, I have the Vari-Cyclone fan - running at 12V with the speed control. It works really well.
The only place I was worried about voltage drop was for the three way switches to the lofts so I used low power draw relays in the light boxes for these (not automobile relays as they draw a lot of power).
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MtnDon
Member
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# Posted: 21 Jun 2016 10:32am
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Quoting: Asher Don't use solid wire for 12v systems, electrical current is carried along the surface of the wire not the inside, that's why heavy amp draw wiring use multi-strand wiring,
Partial truth. There are valid reasons for using stranded wire. The most obvious is that stranded wire is easier to bend and handles vibration better. The surface effect mainly only comes into effect on high frequency AC circuits. DC has no frequency so no advantage there. But there are exceptions to everything... starter motor / battery cables that handle large amperage currents (inverter cables included) use finer strands to keep the cable temperature down. That involves current of 200 amps or more. Different situation compared to running LED lights or a small DC fan motor or pump.
On a low voltage DC system with typical lights and small appliance uses either solid or stranded will do the job, That said, not all wires carry approval for use in a residence. The wire you buy at the car parts store will not pass a home electrical inspection.
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bldginsp
Member
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# Posted: 21 Jun 2016 11:20am
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Whether stranded or solid, a given conductor is manufactured to handle a certain amperage rating. A solid wire rated for 15 amps is no better or worse than a stranded wire rated at 15 amps, in terms of ability to handle the current. Frequency issues is another animal, I doubt it will come into play in most residential situations.
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MtnDon
Member
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# Posted: 21 Jun 2016 03:36pm - Edited by: MtnDon
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Quoting: bldginsp Frequency issues is another animal, I doubt it will come into play in most residential situations.
It does not. Mostly that comes into play when working with radio. The necessity to have flexibility, or not, is the main reason to choose between a stranded or a solid wire.
Watch the length of run and amps carried to prevent large voltage drop. Much more important to factor this in a low voltage system than 120 volts and higher.
Asher, as to why you have burned up wires that has to be either way too many amps for the ampacity rating of the wire. Or maybe cheap wire with insulation having too low a temperature rating. Ampacity values on rated wires are set a temperatures that the insulation does not melt.
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