dc breaker question

cizzi

For my 12 volt solar system would a

"Midnite Solar 15 amp 150 VDC din rail mounted breaker"

be good? few reasons I ask.. it says "150 VDC".. second of all i never seen one of these close.. how do they go connected? with AC breakers you connect them in the bus bar (snap or screw) and connect the black in the screw..

but im looking to buy a small midnight solar baby dc box ( http://www.theresourcestore.ca/proddetail.php?prod=MN-BB ) without any bus bar as far as I can tell, how do the wires connect to the breakers? is there 2 screws? one for the postive and one for the negative? thanks

Solar Guppy

Re: dc breaker question

For 12VDC, go to home depot and get an AC disconnect box ( like 15 dollars ) and then get some Square-D QO 15 amp breakers which are DC rated to 50VDC

BB.

Re: dc breaker question

Cizzi,

You don't need to open a new thread for each question you have... Since this is all about your one system, there will be less confusion if we keep the discussions (and answers) all on one thread.

Or you end up with the same question asked/answered like this one on breakers in several threads.

-Bill

JESSICA

Re: dc breaker question

Cizzi:

The Square D QOU 15 amp DC circuit breaker can be mounted even without the box or enclosure.

Best price here: http://store.solar-electric.com/squardqou15a.html

cizzi

Re: dc breaker question

My local home depot would have this:

http://www.homedepot.ca/webapp/wcs/stores/servlet/CatalogSearchResultView?D=901398&Ntt=901398&catalogId=10051&langId=-15&storeId=10051&Dx=mode+matchallpartial&Ntx=mode+matchall&recN=0&N=0&Ntk=P_PartNumber

Which is a square D QO 15 amp breaker however in the description and specs it does not mention DC.. is this the same breaker you folks are talking about?

n3qik

Re: dc breaker question

Yes, that is the type you want. I have two of the QO distribution panels with 12 of the QO breakers.

The QO line is UL rated to 48VDC at 5000 AIR.

Here is link to the PDF file:
http://ecatalog.squared.com/techlib/displaydocument.cfm?id=0730CT9801&action=view

Goto page 5

cizzi

Re: dc breaker question

its just that the breaker in that link doesnt look like the one someone else posted here: http://store.solar-electric.com/squardqou15a.html

cizzi

Re: dc breaker question

allright I know how to wire an AC panel, as far as DC.. what are the basic rules? would I only use 1 line with my hot live wire and use the white bus bar for my black (negative) and then clicp in my breaker?

BB.

Re: dc breaker question

Wiring is pretty much common sense... Wire the + through the breaker to your load. The return back to the Neutral bus bar... Don't tie "neutral/negative" bus bar to ground except in one location--typically where the earth ground wire enters near the ground rod.

Also, remember that this is not a center tap transformer (120/240 VAC) system... So that the "neutral" from an "A" and "B" phase of a 120/240 VAC do not cancel in a DC circuit--they add.

Wiring colors--If you will ever wire this for 120 VAC--then follow AC wiring colors/practices... And use a wrap of color tape on each end of the run to identify +/- leads (red=+? black=+? white=-? grn=-? etc.).

If you are using automotive type electronics--typically the car chassis is "GROUND"... In your wiring here, you will find that "-" is not the same as "earth gnd/grn"... So, when wiring a car type radios/cb/ham/etc... You may end up with issues where earth and "-" ground can case a volt or so difference with the chassis/antenna grounds, etc. Think how you want things wired, and make sure you avoid having currents share return paths, or issues where two cases touch and you get a (typically small) arc.

-Bill

cizzi

Re: dc breaker question

thanks bb.. also found this diagram which simplifies things for me as well..

http://www.newmarpower.com/Electrical_Panels/Accessory_Panel_Wiring2.jpg

cizzi

Re: dc breaker question

also since i'm using just 1 line of the bus bar (1 phase) I would only connect my breakers on the rows which use that bus bar right? skipping one.. makes sense?

BB.

Re: dc breaker question

You can also just "bus" the A and B bus bars together... And both will be a "+" connection.

-Bill

Solar Guppy

Re: dc breaker question

That Diagram has the + and - reversed on the load side. If you look closely, it shows the + coming from the common - bond, not the breaker

cizzi

Re: dc breaker question

thanks for pointing that out.. thought it was weird too.. since you dont want to put a + and - on the same bus bar