12V DC wiring for LEDs around the house (for solar use)

[pleppik]

....maintain the decorum and orientation of the forum.

Aha! I see your mistake!

[mapmaker]

I have 2 12v battries in series. I could harvest one of the batteries to get 12v. I could harvest other battery for other section of the house. This way i'll have roughly balanced 12v loads on the batteries.

That will be a big mistake. You batteries will NOT stay balanced. If you want 12 volts from 24 volts get a DC to DC converter.

Also, as I mentioned previously, the voltage of a 12 volt battery varies quite a bit depending on the charge-discharge cycle. With a DC to DC converter you will have an unvarying 12 volt supply.

--mapmaker

[russ]

I AM living there since 25 years.
Please lets not stray from the discussion and maintain the decorum and orientation of the forum.

Merely answering your silly point.

[bhvm]

Pardon? I lived there for 16 plus years - please don't spread that BS.

I AM living there since 25 years.
Please lets not stray from the discussion and maintain the decorum and orientation of the forum.

[russ]

1)

5) Without a doubt India houses some of the Genius people. Here people are co-operative and focus on solving issues rather than mocking down on conditions. Conditions are something we cannot change but we can try to upgrade what we have.

Pardon? I lived there for 16 plus years - please don't spread that BS.

[bhvm]

hi!

So is letting the population starve to death, and sub standard building codes that kill people needlessly. That is why you are still a 3rd World Country.

A 24 AWG pair can only safely carry .5 amps if in free air. 2 pairs in a raceway or bundle .4 amps each pair or total of .8 amps. 25 pairs like the Telco uses only .1 amps per pair or 2.5 amps total. Now what happens if those rats and mice in your house chew through some of those wires forcing the current they were carrying onto what wiring is left and over heating them catching fire leaving you with some roasted rats and mice for dinner and no house? Just tell your family that is normal practice here in India. It would be the truth. .

With a 24 AWG at full capacity of .5 amps on a 12 volt system (6 whopping watts), max distance to 11 volts (9% power loss on wiring) is 15 feet one way. Beyond that is a Brown Out and unusable.

T5 efficiency is 100 l/w. Best efficiency for LED on the market today is made by Cree is 80 l/w and they are not available in India. You got a lot to learn.

To do what you want requires no expensive unreliable solar. All you need is a rectifier > batteries > 240 VAC inverter to carry you through 3rd world power outages every day.

1) Thanks for the Maths, This was what I was looking for. So in your recommendation, using Drivers/transformers on Existing 240v wiring will be more efficient than straight 12v LED?

2) Rat proofing is a normal practice in India. however i will think of the maths in case one conductor snaps off or has a short.

3) we are using Philips T5s and its mentioned in spec as 80 LM/w. We are using CREE XMLs or Cree COB 10W LEDs which offer 150LM/w in lower current. Even at full current (with decent heatsinks) they're close to 120LM/w. lets call them 100Lm/w for driver losses.

Best Cree LED today is about 200 LM/w or more

http://www.cree.com/LED-Components-and-Modules/Products/XLamp/Arrays-Directional/XLamp-MKR

http://www.cree.com/News-and-Events/Cree-News/Press-Releases/2013/February/276-LPW

But it does not offer good Lumen/$ ratio so we are sticking to 10W COBs.

4)I have the inverter already as mentioned. But It cannot survive 8 hour power cuts daily.

5) Without a doubt India houses some of the Genius people. Here people are co-operative and focus on solving issues rather than mocking down on conditions. Conditions are something we cannot change but we can try to upgrade what we have.

P.s- All the inverters sold in india have Built in Battery Charging when connected to Mains. They also offer UPS function and Voltage regulation.

[bhvm]

Anytime you exceed the ampacity of a conductor, you risk a fire. Ampacity is DEFINED as the maximum SAFE current carrying ability of a conductor.

When you double a conductor it is difficult to make the current split up evenly between the two (or more) conductors, therefore one conductor may carry too much of the current. Also, if any corrosion or other poor connection occurs, one conductor may not carry its share. If one conductor is short circuited, it will carry all the current.

It is difficult to design proper overcurrent protection (fuses or circuit breakers) for multiple parallel conductors.

12 volt wiring in a home is a mistake, even if you use larger wires. Get a small inverter and use the existing 120 volt wiring for the house. It will be cheaper and safer than trying to make a 12 volt system work.

btw, where will the 12 volts come from? In your other thread you had a 24 volt system.

--mapmaker

Thanks for the info.
I DO have a 240V inverter. It powers all the ciritical loads. I would like to add solar as not to stress out the inverter and act as a support to it.
I have 2 12v battries in series. I could harvest one of the batteries to get 12v. I could harvest other battery for other section of the house. This way i'll have roughly balanced 12v loads on the batteries.

My house is already adorned with Self made LEDs and lamps.

[Sunking]

Doubling conductors is a common practice in India.

So is letting the population starve to death, and sub standard building codes that kill people needlessly. That is why you are still a 3rd World Country.

A 24 AWG pair can only safely carry .5 amps if in free air. 2 pairs in a raceway or bundle .4 amps each pair or total of .8 amps. 25 pairs like the Telco uses only .1 amps per pair or 2.5 amps total. Now what happens if those rats and mice in your house chew through some of those wires forcing the current they were carrying onto what wiring is left and over heating them catching fire leaving you with some roasted rats and mice for dinner and no house? Just tell your family that is normal practice here in India. It would be the truth. .

With a 24 AWG at full capacity of .5 amps on a 12 volt system (6 whopping watts), max distance to 11 volts (9% power loss on wiring) is 15 feet one way. Beyond that is a Brown Out and unusable.

T5 efficiency is 100 l/w. Best efficiency for LED on the market today is made by Cree is 80 l/w and they are not available in India. You got a lot to learn.

To do what you want requires no expensive unreliable solar. All you need is a rectifier > batteries > 240 VAC inverter to carry you through 3rd world power outages every day.

[mapmaker]

May I understand why it's illegal and causes fire?

Anytime you exceed the ampacity of a conductor, you risk a fire. Ampacity is DEFINED as the maximum SAFE current carrying ability of a conductor.

When you double a conductor it is difficult to make the current split up evenly between the two (or more) conductors, therefore one conductor may carry too much of the current. Also, if any corrosion or other poor connection occurs, one conductor may not carry its share. If one conductor is short circuited, it will carry all the current.

It is difficult to design proper overcurrent protection (fuses or circuit breakers) for multiple parallel conductors.

12 volt wiring in a home is a mistake, even if you use larger wires. Get a small inverter and use the existing 120 volt wiring for the house. It will be cheaper and safer than trying to make a 12 volt system work.

btw, where will the 12 volts come from? In your other thread you had a 24 volt system.

--mapmaker

[bhvm]

The ampacity (safe current carrying capacity) of 24 gauge wire is 0.577 amps.

Doubling them is very dangerous (illegal in this country) and may cause a fire.

--mapmaker

May I understand why it's illegal and causes fire?

Doubling conductors is a common practice in India. If a conductor of sufficient diameter not available, it is permitted to be Doubled or even Tripled to help carry current. Also Routing multiple paired conductors through concrete/walls is easier than a single thick and stiff wire. It is usually done for heavy equipment like Air cooling, heaters and Industrial appliances.

[mapmaker]

1)I am aware that 12v wiring needs more amps, hence i was trying to find out what is current carrying capacity of 24AWG wires? what if I double them?

The ampacity (safe current carrying capacity) of 24 gauge wire is 0.577 amps.

Doubling them is very dangerous (illegal in this country) and may cause a fire.

--mapmaker

[bhvm]

Very flawed logic, as 12 volt systems are very inefficient. You had an extreme problem with your panel wire being too small at 30 volts. At 12 volts the losses will increase 400% for a given power level. To overcome those losses means much larger more expensive wire must be used. Just for a very small 10 amp circuit at 12 volts in a house means looking at 10 mm2 or larger wiring only to carry a maximum of 120 watts. At 240 volts AC you can use a 10 amp circuit using 1 mm2 carrying up to 2400 watts.

Another flaw in your logic is a T5 light source is more efficient than LED. Your real issue is your design logic is flawed, and not knowing what it really takes to do what you want. If you have commercial power available you do not need any solar to do what you want to do. All you need is a rectifier to charge batteries when you do have commercial power. Would be a lot less expensive and way more reliable.

1)I am aware that 12v wiring needs more amps, hence i was trying to find out what is current carrying capacity of 24AWG wires? what if I double them?

2)I do not undestand how T5 can be more efficient than LEDs. They're about 80Lm/w. Good leds are approaching 120 Lm/w. Plus DC means i could save transformer losses.

3)The thing is making best out of what we've got. Its not a new house so it will be better if we could utilize something existing.

4) Commercial power in India is Crap with a C. I've already lost a many gadgets due to poor regulation and voltage fluctuations. My target is to shift all critical and light loads on Solar. There are 8 hour long power cuts anyways.

It does make sense to have a small inverter which powers only your LED or fluorescent lights, and if necessary a larger inverter for higher power loads.
A small (low power) inverter will use less power from the batteries when it is not producing output and can use smaller wiring to the batteries.

One thing that you have correct about your plan is to convert all of your incandescent lighting to either LED, conventional fluorescent (T8 or T5 tubes), or compact fluorescent (CFL). That will save you a large amount of power even if you still distribute the energy at 120 or 240V AC.
You will have a much wider selection of lamps and fixtures.

1) The inverter currently only powers critical loads like laptops, Mobile charger , CFLs, Path lights and few small fans. Rest everything is on mains.

2) Incandescents? I was born and brought up under Florescent. That's how old they're and I absolutely HATE incandescents. Since 5 years I have already converted my Most of Lighting to LEDs. problem is they use drivers/Adapters/Transformers . I was planning to remove those conversion with direct 12v Wiring.

3) Incandescents are practically Banned in india. Huge power cuts means they're also impractical to run.

My concern is the 24 awg wire size. A 12 volt DC system will work for small loads that are close to your battery. Running 12 volt wiring across your home using very small wire size will increase the voltage drop considerably and probably result in a voltage too low to turn on those LED lights.

It is also not good to run parallel runs of wire. It is better to increase the wire size enough to not have any or very little of a voltage drop at the load.

24 AWG telephon eis not going to work. You are going top need 10 mm2 or larger. That is only a difference of magnitude of about 1000. You will go broke buying copper to operate at 12 volts.

thanks, looks like i'll have to make a trial run by powering a spool of LEDs across the house.
Its not easy to Rip out 10 rooms worth of wiring

[Sunking]

24 AWG telephon eis not going to work. You are going top need 10 mm2 or larger. That is only a difference of magnitude of about 1000. You will go broke buying copper to operate at 12 volts.

[SunEagle]

My concern is the 24 awg wire size. A 12 volt DC system will work for small loads that are close to your battery. Running 12 volt wiring across your home using very small wire size will increase the voltage drop considerably and probably result in a voltage too low to turn on those LED lights.

It is also not good to run parallel runs of wire. It is better to increase the wire size enough to not have any or very little of a voltage drop at the load.

[mapmaker]

One more consideration in favor of a small inverter is voltage stability. A 12 volt system may vary its voltage from 11 to 15.5 volts during the charge-discharge cycle. This does not agree with many 12 volt lights and appliances.

Where would you get the 12 volts? in your other thread you have a 24 volt system.

--mapmaker