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Bret
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# Posted: 8 Oct 2015 02:51pm - Edited by: Bret
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My brain is fried from searching. So here is my simpleton question of the day. I have 24 volt panels and plan for the system to remain 24vdc through out. The price of inverters and lack of complex install keeps me coming back to dc all the way. Some led lights, small pump for water pressure, ceiling fan.
Can I use regular ac light fixtures with the appropriately based led light? Or do I need special rv/marine typed fixtures. Also, where is a good source of dc plugs and switches? Thanks for the kind help. My head is slowly wrapping itself around this dc business.
Bret
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MtnDon
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# Posted: 8 Oct 2015 03:24pm
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Before you decide on using a 24 VDC battery system check the panel output. To properly look after a 24 VDC battery you need to have pretty much a minimum of 36 volts as the panel Vmp rating.
Inspections? DC may raise the inspector eyebrows a lot.
Also, IMO, a DC only system is only suitable for small systems or at least systems with small amperage DC loads. Reason being large amp, low voltage loads require large diameter wire and that is also expensive. So if the loads are mainly low voltage DC LED lights, fine.
If there is no AC at all in the cabin, IMO, it is okay to use AC fixtures if you can find the appropriate DC voltage lamps. I say that because that reduces chance of someone trying a 120 VAC lamp in the socket that is wired to low voltage DC.
AC switches are okay for DC, IF you keep the loads very small; like LED's. Otherwise the AC switches can burn out quickly. Carling Switch makes some very nice DC rated switches. I've seen them on ebay. They are what I have used for our DClow voltage circuits. They don't fit in std AC boxes so that can complicate things.
If you want to use AC type lamps with DC bulbs, that have a plug to be inserted into an outlet you might consider using a NEMA, 250 volt typeof plug and outlet. That virtually eliminates any chance of somebody plugging a 120 AC plug devoce into the DC circuit. Types in chart form here. I havre used the NEMA 6-15 and 6-20 types in DC circuits.
The potential issue with DC on AC switches is burning the contacts. DC creates large arc flames when making and breaking an active circuit. AC does not. AC does not create the large flash over because the AC current stops and reverses 60 times second. DC does not and with a large enough load (amps) can burn the switch and start a fire. DC switches have much heavier metal parts.
Remember you still need fuses or breakers. And again most AC fuses and breakers are not suitable for DC. Use marine or auto or the Square D brand, model QO or QOC breakers can handle DC voltage in a 24 VDC system. Use same amp rating for DC as would be for AC.
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Bret
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# Posted: 8 Oct 2015 04:34pm - Edited by: Bret
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Thanks for the timely input. The panels are the solarpeace 195 watt 24 volt. These are the specs:
Vmp: 37.0 volts
Voc: 45.2 volts
Imp: 5.27 amps
Isc: 5.63 amps
I like the idea of the heavier guage switches and nema 6-15/20 plugs and receptacles. No sense in having some one plug in something they shouldn't.
A nice thing about the cabin is that it is off grid and the powers that be in the rural county only require a building permit with no inspections. Which doesn't mean I want to do anything half-assed.
I plan to run all the wires in metal, surfaced mounted conduit.
I think that 24v requires #12 guage for the amp/watt/length of run, and I have some various #12 colored wire from my garage/shop project. Might as well use it up.
Thank you for taking the time to answer. So, I guess I can find some decent looking ac lighting fixtures and use something like this https://www.altestore.com/store/Lighting-Fans/LED-Lamps-Fixtures/Phocos-3W-LED-Bulb-1 224VDC/p11577/
Again thanks
Bret
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