Laws re 12v DC in homes

New to renewable energy? Have questions? Here's a great place to ask them and view information about wind and solar power basics.

Laws re 12v DC in homes

Postby Roundsole » Sun Jul 05, 2015 2:56 pm

Unlike 240v AC laws, what laws exist re running 12V DC and 12V DC lights thru a home?
Roundsole
Solar Supporter
Solar Supporter
 
Posts: 15
Joined: Sun Jun 14, 2015 2:21 pm

Re: Laws re 12v DC in homes

Postby davidg » Mon Jul 06, 2015 1:00 pm

Roundsole wrote:Unlike 240v AC laws, what laws exist re running 12V DC and 12V DC lights thru a home?


Great question, wiring should at the very least be done by a competent person. making fixed wiring safe regardless of voltage should always be done to a proper standard.

By the way for what it worth wiring to at at least LV and using LV cabling will mean in the future it could be used for LV .

Wired a few sites for LV, then installed all 12V lighting, works out nicely, offers future flexibility if wanted or needed.
SPS Standalone Power System/Hybrid specialist - Store the Sun!
SELECTRONIC SPMC482-AU, 8.2kW's of Arrays
Selectronic Certified AC-Coupled Fronius 8.2kW Inverter
1900Ah 48V Bank

An OTT Genset for a house.
PVOutput Stats

Sparkys light up your life :)
User avatar
davidg
Solar Crusader
Solar Crusader
 
Posts: 2102
Joined: Sat May 05, 2012 7:38 pm
Location: Dandenong VIC- *Really don't like Power Retailers at all.

Re: Laws re 12v DC in homes

Postby BeeMee » Wed Jul 08, 2015 9:33 am

My former home had 240V but for 5 years there was no electricity backbone, so we set up 12V. We kept it installed after the grid power turned up, and glad we did. When there was power failures due to lightning and storms, we could still operate with lighting. Never looked back, and would love to set it up here as well but this home may be a bit more difficult as it is already established. Our former home was built by us, including installing septic, electrical wiring, water, etc. So having everything opened with no walls and ceiling made the job easier.

We used 12V wiring and perhaps over clamped into position, but we secured it every 12 inches. All areas were name planted as 12V wiring. So future owners would know what it was. There really are some dimwits out there who don't know the difference between 240V 10/15amp cable to a standard 12V 4/8mm cable. One born everyday I guess.
I would also choose specific colours totally unrelated to the 240V system to assist in clarification.

But I say go for it mate, just make sure everything is secured well so it doesn't move. If using a 12V battery as we did initially, we had a battery charger added to it once the grid was connected, prior to that, we had a generator to recharge the battery. But the battery on full charge used to last almost a week.
Now with solar, you could make that the charging point for your battery recharging.
Good luck.
BeeMee
Solar Fanatic
Solar Fanatic
 
Posts: 29
Joined: Fri Aug 17, 2012 3:21 pm

Re: Laws re 12v DC in homes

Postby Roundsole » Wed Jul 08, 2015 11:31 pm

Thanks guys, appreciated.
Roundsole
Solar Supporter
Solar Supporter
 
Posts: 15
Joined: Sun Jun 14, 2015 2:21 pm

Re: Laws re 12v DC in homes

Postby swampdweller » Thu Jul 09, 2015 3:09 pm

The 12V wiring must be installed in accordance with AS/NZS 3000 - Australian/New Zealand Wiring Rules.

The 12V wiring itself is classified as Extra Low Voltage (ELV) wiring and from memory (and I am absolutely no expert on the Wiring Rules) there are few if any restrictions on how to wire up ELV cables and equipment as such, but the clauses on separation of ELV, Telecommunications and data wiring from higher voltage wiring are very important. For example, they must not run in the same enclosure or in close proximity and there are clauses regarding insulation levels and cable types. The cables should be in polarized DC pairs self evidently for DC wiring. Using 240V type cables is asking for catastrophe, because further down the track someone might assume it's 240V wiring and put 240 V onto it.

I would suggest you get hold of a copy of AS/NZS 3000 and seek advice from an A Class Electrician.
swampdweller
Solar Supporter
Solar Supporter
 
Posts: 21
Joined: Wed Jun 19, 2013 10:19 am
Location: Cape Jervis, SA

Re: Laws re 12v DC in homes

Postby Roundsole » Thu Jul 09, 2015 9:34 pm

What do you mean by "cables should be in polarized DC pairs"?
Roundsole
Solar Supporter
Solar Supporter
 
Posts: 15
Joined: Sun Jun 14, 2015 2:21 pm

Re: Laws re 12v DC in homes

Postby swampdweller » Fri Jul 10, 2015 12:13 pm

For example, if you buy 4mm2 double insulated flexible cable which is commonly used to wire up PV panels, it's a 2 core cable with one red and one blue core, so anyone who looks at the cable can see it's intended for DC use and you can easily tell positive from negative. It's usually also marked as such at intervals along the sheath. A good cable for light fittings, especially LEDs, is 2 core 0.75mm2 "figure 8" cable which is available with a (usually) black trace along the insulation of one core, in DC wiring the usual convention is the core with the trace is positive.
swampdweller
Solar Supporter
Solar Supporter
 
Posts: 21
Joined: Wed Jun 19, 2013 10:19 am
Location: Cape Jervis, SA

Re: Laws re 12v DC in homes

Postby davidg » Fri Jul 10, 2015 7:23 pm

swampdweller wrote:A good cable for light fittings, especially LEDs, is 2 core 0.75mm2 "figure 8" cable which is available with a (usually) black trace along the insulation of one core

Terrible cable for fixed wiring it's only single insulated. Quite light on in terms of copper area mm2. Not even allowed anymore for table lamps etc all that is now double insulated.

For fixed wiring you should should use a double insulated cable even regular TPS from an electrical wholesaler in 2.5mm2 then using a permanent marker write at distances of say no more than 2 metres and at each bend just to be sure something like this "WARNING 12VDC" secure it roughly every 600mm, make it so it can not be "walked on", ie clip it or cable tie to the side of timber etc not to the top and you should get a good result. You can get away with using regular "Clipsal" or similar switch mechs for 12VDC label the wire again "12VDC" in the wall where the cables and the switches are, remember the current rating ie they are designed for a max of 10A for instance just because it's ELV lighting does not mean you should ignore current ratings.

The end result should look like any other household electrical lighting switch system when finished.

If you stick to not more than a total of 10A for 12VDC (120W max) as long as the cable runs are not too long you should not have any issues.

8-) 8-)
SPS Standalone Power System/Hybrid specialist - Store the Sun!
SELECTRONIC SPMC482-AU, 8.2kW's of Arrays
Selectronic Certified AC-Coupled Fronius 8.2kW Inverter
1900Ah 48V Bank

An OTT Genset for a house.
PVOutput Stats

Sparkys light up your life :)
User avatar
davidg
Solar Crusader
Solar Crusader
 
Posts: 2102
Joined: Sat May 05, 2012 7:38 pm
Location: Dandenong VIC- *Really don't like Power Retailers at all.

Re: Laws re 12v DC in homes

Postby Privatteer » Sat Jul 11, 2015 10:02 pm

If you are going to use TPS at least use the black or yellow sheathed version. Same price, just might have to wait a few days for supplier to get it in.
Stage 1:
Fronius Primo 5 + 6.6kW Canadian Solar
Privatteer
Solar Crusader
Solar Crusader
 
Posts: 476
Joined: Sat Nov 19, 2011 12:00 am
Location: South West WA

Re: Laws re 12v DC in homes

Postby Tracker » Mon Jul 13, 2015 1:13 pm

..
+1 to pre-wiring with 240V cables.... and
+1 to ordering a special color outer sheath, to make it stand out and be different - "Caution Will' Robinson"

and in tune with the concept.. remember that 12V is the least desirable voltage..
Low Voltage = High Current = Higher voltage drop

Given that many LED lamps work over extended voltage ranges, it would be good to look at a complete PLAN using a higher voltage and suitable fittings..

You can buy oh so many different voltage LED drivers on Alibaba..

and - if 12V is where your MUST start,
there are very efficient UP-Converters that might be worth the try, bucking 12V to say 36V for transmission..
..
.
Retired Engineer and keen PV experimenter - Always ready to learn and share.
2 x CMS2000 (fan cooled) GCI and SE 170W panels
1.7kW First Solar/Outback Island circuit - Peak Replacement Power
Governments won't save the world :-) They will just TAX it :-(
Tracker
Solar Crusader
Solar Crusader
 
Posts: 5113
Joined: Wed Sep 23, 2009 5:54 am
Location: SYDNEY --- EA - Network, Retailer - EA

Next

Return to Q&A - wind and solar power basics

Who is online

Users browsing this forum: No registered users and 1 guest

new solar power specials