12 VDC Home System

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Can you try and kerb your writing!! Just keep to the point and don't waste so many words each time!!!!!

I'm in a similar situation. 3- 44watt solar panels plus a 24 watt wind generator. Recently hooked up to a 200w (400w start-up) converter via a 240ah marine battery that I can isolate from grid power. It gives me all the illumination I need from CFL's around the house when the power is down.

The alternative is to go to a marine catalogue and buy 12vdc CFL's. 2-3 times the price of 120vac CFL bulbs. I may have to buy one anyway, as bathroom lighting is strictly 12vdc, and I hate to miss the toilet at 2 AM. All my CFL's are less than 20w, and it has shown up in my monthly energy bills. I am typing this with a 9w CFL bulb overhead. Plenty of light.

Use the excess energy to run fans, blowers, pumps, etc..

...I hate to miss the toilet at 2 AM.

Wow, are you aiming from the bathroom door?

The 12 volt 13 watt CFL's hit the shelves locally this year at the home building supply center(Menard's). They are about a $1 more than the 120 Volt ones.

As far as circuit breakers you can use the standard ones in a low voltage application if necessary. I have done it a few times with out any problems. They just don't take the arc from a higher voltage DC very well. At twelve volts they don't have much problems.

Boats have nice electrical panels, with breakers, voltage meters, even amperage meters. Check marine suppliers for a fair price, keep in mind marine supplies are way overpriced, so shop around. You may find the same thing for RV wiring.

Becuase we might not know the specifications on any particular 120v circuit breaker, I would stick with a CB specificaly desinged for 12 volt system. Wether you place protection on each individual circuit (best) or just a main CB based on total circuits wired.

Like the CBC-HB Stud-Mount Circuit Breaker (12 Volt, Type I) you might be able to save some money with an ebay search for these too.

They go from 10 -50 amp with lower amparage at less than $10. I think this http://terminalsupplyco.com/Store/Product.aspx?pc=CH-30062-20 is pretty nice for your 14 ga (20amp) wire.

You can search google and find great deals like this 20Amp Breaker for only $5

Fusing is used to protect the wire from burning. The fuse "burns" instead and saves the wiring from burning your house down. With a 3000 lb battery supply you have the potential to do a lot of frying of wiring.

As with a house wiring system, a main fuse is used to limit the total current to the input wire size (use the amp rating for the wire from the electrical code based on wire diameter).

The smaller wired branch circuits require individual fuses again based on the wire size.

Does this seem excessive?, probaly not considering the consequences (Surprized an animal hasn't discovered the under house wiring yet.)

Marine supply has water resistant fuse blocks with nice heavy clamps etc. perfect for this application.

14 AWG wire is good for 15A; regular circuit breaker will probably work (I see no reason why 110 V AC circuit breaker should not work on 12 V DC). #1 AWG wire is good for 110 A for aluminum or 150 A for coper (for two wire system; you can protect only one wire). It is better to protect 40 years-old wiring!

Now LED (light emmiting diod) lamps are available; they take even less energy than florecent lamps; it is like2-3 wats for the same amount of light from 60 W incandecent bolb. Good luck!

You can use circuit breaker for 110 volt system,but it must be appropriately rated to protect your equipment.

Patrick Whowha

I would use a standard house circuit breaker panel and protect the branches with 15A circuit breakers.

I would choose this standard electrical equipment over marine equipment because:

(1) anything rated for marine is expensive;

(2) if you ever do get connected to a grid, the conversion to AC will be less;

(2) standard house circuit breakers have the right trip curve to protect Romex house wiring and you will not be bothered by nuisance trips.

Current and time determine the trip point of a circuit breaker. The voltage and voltage type (AC or DC) set the opening of the circuit when tripped. 120vac circuit breakers can break 12VDC without fear of the DC voltage arcing across the breakers contacts when they open.

How do you keep the battery bank charged? I presume you have a generator. Is the generator protected from the battery bank?

Does each battery have fuse protection? If not, I would add standard automotive fusible links.

You did a really good job 40 years ago, but you are right, some fusing is called for......

You have enough sources from all the posts and the ideas for using 12 volt LED lighting is also excellent.

May I also suggest that you put a cheap LED with a 1K resitor across each fuse, when it blows the LED will glow.....makes finding the blown fuse a doddle, day or night!!!

"May I also suggest that you put a cheap LED with a 1K resitor across each fuse, when it blows the LED will glow.....makes finding the blown fuse a doddle, day or night!!!"

That is a GREAT idea! While probably useful to 4123 (thus deserving the GA), I am pretty sure I will incorporate (at least some version of) this into several of my future projects. Thanks!

I have actually seen, some years ago, resettable car fuses with a LED across them....

The biggest problem with the LED is that even though the fuse is broken, whatever it supplies must be effectively switched on to light the LED....

Most of the equipment manufacturers make a pre-wired version of a fuseholder with an LED tell-tale built in.

Personally iI would always use a breaker. No temptation to put the wrong size fuse in when you get a trip!

One place where there should be a fuse is the main fuse which should be as close as possible to the battery terminals.

3,000 lbs of battery is between 3,00Ah and 4,000Ah (Dependant on battery type) with a short circuit capability upwards of 70,000A!

You are extremely lucky that you have had no faults in forty years.

Regards

Chas

The battery you describe can create a huge arc for a long time. You must install overcurrent protection. Many circuit breakers are rated for ac and dc. The DC rating is less because it is harder to extinguish a DC arc (it never crosses the zero point like AC). #14 should be fused at 15 amps. Never use automotive fuses. You must use UL listed components to be legal. I would fuse the positive lead from the battery and then set a small panel with 15 amp fuses to connect to each romex. The home and life you save may be your own.