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Topic # 138311 29-Dec-2013 19:31 Send private message

Hey guys,
A friend recently asked about light fittings for his new house purchase which needs to be done up.

I started thinking about the costs etc. and that recessed LED DC could be a viable option due to the low power consumption and life. Having a quick look at ali express, there are some options for this (and some cool RGB effects):

http://www.aliexpress.com/item/9W-LED-RGB-downlight-Square-Size-140-140mm-3X3W-RGB-tri-chip-12VDC-controllable-dimmable/1025959711.html

That got me thinking, he would then need a DC converter for the lights. To do the whole house he would needs lots of converters so why not just have a singluar DC supply near the switch board with one larger adapter? You could then use DC for other devices which in the future could use it as an input e.g. electronics like tv, computer etc.

For things like lighting, you could use much lighter cable which would probably be much cheaper, you could do work yourself since its low voltage and it would be easier to hook your own wind turbines, batteries, solar photo voltaic into the mix.

Is DC distribution within a home/business viable or a good move?





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  Reply # 958781 29-Dec-2013 20:11 One person supports this post Send private message

Actually, because it's low voltage you need a heavier gauge cable for the wattage used.

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  Reply # 958788 29-Dec-2013 21:02 Send private message

Consider regulations, standards, and insurance. A professional won't install things that are unlicensed, and if the house burns down because of them would it still be insured?




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  Reply # 958790 29-Dec-2013 21:07 Send private message

There are a few emerging LED lighting over CAT5 options: http://www.lumencache.com




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  Reply # 958830 29-Dec-2013 22:07 Send private message

DarthKermit: Actually, because it's low voltage you need a heavier gauge cable for the wattage used.


Yes, but the wattage of the LED lamps is MUCH lower.

My next build will have 2 switchboards a 12/24v one for low voltage lighting , the other for 230v with an option of linking the 2 together.

i.e. initially use 230v LED lamps based on ES lamp holders, then as low voltages ones become available swap over to them , unlink the boards
put in solar panels/batteries.

During summer use the panels to power up the heat pump to keep the house cool, during winter use them to power the lights





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  Reply # 959088 30-Dec-2013 15:34 Send private message

What about PoE? Pretty sure that doesn't invalidate our insurance and we already run it... With the new idea about PoE standard going to 25 watt with PoE and that's only on 2 pairs 24AWG. on 23AWG (cat6) and using all 4 pairs that could easily be going near 60w. That could power heaps of stuff - all lighting easily even a big screen tv!

I like the idea of PoE also since everything is negotiated reducing the chances of electrocution etc.





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  Reply # 959108 30-Dec-2013 16:21 Send private message

I've been thinking about this for some time. Would be fine if you place a power supply just after each switch where you have a cluster of lights. Even in our bedrooms we have 2-3 lights per room, living space is grouped in 4. Typically you are looking at about 300mA per LED fitting. Due to the voltage difference, that is about the same as a 70W incandescent. The real issue with cable size is that a 1V drop at 240V is minimal, but a 1V drop at 35V is more significant. The cable is fine, the power delivered to the light is not so good.

Reason for placing the transformer after the switch is because the switch is designed for AC which has different contact plating requirements than AC.

In the end I've decided to go for dedicated LED fittings with an external power supply at the fitting, so when the power supply dies then I can replace it without replacing the fittings. LEDs will last in NZ's cool climate, it is the power supplies that will fail first.

I can recommend fittings from http://www.qualityledlighting.co.nz/




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  Reply # 959145 30-Dec-2013 16:57 Send private message

Zeon: What about PoE? Pretty sure that doesn't invalidate our insurance and we already run it...


All that equipment is probably approved for use in NZ though. Importing from cheap Chinese websites is a risk, both in terms of quality, performance, what arrives, and insurance.




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  Reply # 959168 30-Dec-2013 17:37 Send private message

PoE is very low wattage, you'd struggle to start a fire even if you set out to do it.

Yes, LED's are far lower wattage than incandescent lamps, they have very similar wattage-lumens to CFL's. You need to consider light output too, a 9W lamp would not give you a lot of light, a medium to large lounge may require 9 or more that size, a kitchen would probably need more.


I can think of many reasons this isn't a good idea

1) All lights will be on the same power supply and therefore circuit. If the breaker trips, or the power supply fails you're totally in the dark.

2) Cable would probably have to be significantly larger to compensate for the load and therefore would cost a LOT more.

3) Voltage drop is a significant factor with long runs of low voltage wiring.

4) Low voltages are more likely to be affected by high resistance switches. Mains voltage typically burns off any dust, moisture or gunk, 12v doesn't.

5) You'd need at least some additional short circuit and over current protection for the low voltage circuits to protect your transformer and prevent fire.

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  Reply # 959534 31-Dec-2013 12:15 Send private message

No reason you can't series connect heaps of 3w or similar emitters off a single driver, it's how they are made to work since leds need the current limited not the voltage.

thing you have to watch is that get over 32v which is 10 leds and it's not extra low voltage anymore.





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  Reply # 959716 31-Dec-2013 20:28 Send private message

Below 50VAC or 110VDC is extra low voltage

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  Reply # 959834 1-Jan-2014 11:45 Send private message

We have DC lighting in our house - heaps of little LED's poking through the plaster ceiling with an occasional light sensor. When the ambient light goes dark, the LEDS in the area will come on. Its about as bright as a moonlit street or paddock.

Anyhow, we have a bunch of 12v 5 amp transformers in the attic so the idea is whenever we want to install something that uses 12v, we can just wire it to the nearest 12v transformer.

Also you can now get wall sockets with usb power plugs built in

POE limitations
There are many different forms of power over ethernet
- Negotiated
- 12-24v on +BLUE -BROWN
- 12-24v on -BLUE +BROWN
- assorted others up to 48v

Anywho, an LED Tv uses 50 watts for a 32" according to CNET and if you are sending that down a two-pair POE, the cable distance before the voltage drops off wouldnt be very far. You would need to send 48v down the cable to make it worth while, which means any 12 or 24v poe devices in the house need converters - or you would have to use a negotiated system which not all devices are capable of.

Personally i think USB plugs everywhere is probably the thing to do - though i do wish they would raise the USB voltage to 12v instead of 5v




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  Reply # 959969 1-Jan-2014 16:26 Send private message

Prior to starting an upgrade of the lighting at home, I spent some time reviewing the options. I decided that traditional wiring with 230 V was costly, inflexible and inefficient from an energy point of view.

LED lighting was observed to be the way of the future. the lumen output of the fittings was improving rapidly, costs are also coming down.

LED lights generally fall into two categories - Constant Voltage & Constant Current. In most applications this is taken care of by the driver that is supplied with the fitting and the 230V mains cabling is hooked up to this driver.

I realised that I did not necessarily need to use these drivers and could achieve some good results from other items that are readily available.

I decided to install a central control cabinet for the lighting. This cabinet has 3 switch mode power supplies, 12 VDC, 24 VDC & 48 VDC.

MR16 LED's are typically 12 VDC Constant Voltage (Typically used to replace 50W Halogens Down Lights).

The LED strip that I am about to install is 24 VDC Constant Voltage. The 24VDc is also the control voltage of the system & is also wired to the light switch's etc.

The 48 VDC is used to supply the drivers for the 13W down lights in the Lounge, Kitchen, Dining & Conservatory. There are 350mA LED drivers installed in the control cabinet for these fittings.

Each light is individually wired back to the control cabinet. The MR16 Fittings are fused in groups (IE outside lights at the front of the house), and the rest are individually fused.

A lot of the equipment that I have used in the control cabinet is industrial in nature, and is readily available through most electrical wholesalers.

I have opted for a centralised control philosophy. I also looked at the likes of the CBUS system, but felt that these systems were also over priced and lacked the flexibility that I was looking for.

I am fortunate that I have the electrical skills to do this and acknowledge that for most, following the more traditional route is probably still the easiest.

I do however feel some of the emerging technologies for LED lighting will continue to challenge the appropriateness of 230V traditional wiring for lighting - particularly in the domestic environment.










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  Reply # 960474 2-Jan-2014 23:44 Send private message

We have recently started to replace our ceiling lights with recessed down lights which are a standard GU10 240v halogen housing (e.g. http://www.orbitlighting.co.nz/product-catalogue/indoor-lighting/recessed-down-lights/gu10-round-satin-nickel-ca135-downlight which are approx $20 or so from Bunnings/Mitre 10) and then fitting GU10 240v LED bulbs which fit directly into the same housing without any issues.

The reason why we went with 240v is in the past we haven't had much luck with the transformers blowing in the 12v or similar light setups and instead kept with 240v and no need to worry about any transformers blowing, just bulbs.

The second reason is that you can always replace with a standard halogen bulb if you want, otherwise you can simply put in an LED bulb. I purchased a whole bunch from Aliexpress here (http://www.aliexpress.com/item/2pcs-100-Best-Dimmable-9W-4x3W-12W-Super-bright-GU10-LED-Light-Bulb-Lamp-Downlight-Cool/888136857.html) and for the price they are you can't go wrong considering LED GU10 equivalents in NZ are around $15+ each when you can get them from China for about $3-4 USD each.

Third reason is that there are some options in hardware stores for an all-in-one LED down light but I would definitely stay away from those options as once the bulb blows you've got to replace the entire thing including the housing which requires pulling out the unit and re-wiring it each time.

Hope this helps.


~Jonathan

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  Reply # 961618 5-Jan-2014 20:21 Send private message

KGM: Prior to starting an upgrade of the lighting at home, I spent some time reviewing the options. I decided that traditional wiring with 230 V was costly, inflexible and inefficient from an energy point of view.

LED lighting was observed to be the way of the future. the lumen output of the fittings was improving rapidly, costs are also coming down.

LED lights generally fall into two categories - Constant Voltage & Constant Current. In most applications this is taken care of by the driver that is supplied with the fitting and the 230V mains cabling is hooked up to this driver.

I realised that I did not necessarily need to use these drivers and could achieve some good results from other items that are readily available.

I decided to install a central control cabinet for the lighting. This cabinet has 3 switch mode power supplies, 12 VDC, 24 VDC & 48 VDC.

MR16 LED's are typically 12 VDC Constant Voltage (Typically used to replace 50W Halogens Down Lights).

The LED strip that I am about to install is 24 VDC Constant Voltage. The 24VDc is also the control voltage of the system & is also wired to the light switch's etc.

The 48 VDC is used to supply the drivers for the 13W down lights in the Lounge, Kitchen, Dining & Conservatory. There are 350mA LED drivers installed in the control cabinet for these fittings.

Each light is individually wired back to the control cabinet. The MR16 Fittings are fused in groups (IE outside lights at the front of the house), and the rest are individually fused.

A lot of the equipment that I have used in the control cabinet is industrial in nature, and is readily available through most electrical wholesalers.

I have opted for a centralised control philosophy. I also looked at the likes of the CBUS system, but felt that these systems were also over priced and lacked the flexibility that I was looking for.

I am fortunate that I have the electrical skills to do this and acknowledge that for most, following the more traditional route is probably still the easiest.

I do however feel some of the emerging technologies for LED lighting will continue to challenge the appropriateness of 230V traditional wiring for lighting - particularly in the domestic environment.












I actually think that running 240V to each fitting (or small group of fittings) is the most energy efficient way of doing things. Reason being that there is only 1 voltage / current regulator the electricity has to go through. In your system the electricity has to go through 2 conversion stages. And you have 3 power supplies and control circuitry that will be drawing power even when no lights are on.

Although if this system is part of a home automation system then I can understand why you have done it this way. Or do you just have simple light switches in each room?


If you had an "off grid" power system then a DC lighting system is a great idea since it means you are not turning DC from your battery bank into AC. Then back into DC again at the light fittings.

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  Reply # 961629 5-Jan-2014 21:09 Send private message

Also a higher voltage supply means less lossage in the same wiring compared with lower voltage, for the same amount of power supplied.  It is part of the reason households run on 240VAC and not some lower voltage.

I would suggest the most efficient way to do things is to run 240VAC to each transformer running a small cluster of lights (ie for one room/area).  Have this controlled via a standard lightswitch.

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