Low voltage wiring

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  • toscal
    Moderator
    • Oct 2005
    • 2061

    Low voltage wiring

    Since the EU and a lot of other countries will be banning the incandescent bulb by 2012. The main alternatives are mains LED or low voltage halogens and LED lights.
    So this got me thinking if low voltage lighting is the way forward, how are people designing this into their homes. And how are they getting the low voltage to the lights.
    From what I can see there are three real options: transformers installed at the lighting point (so you keep your existing mains wiring) or a very large one at the consumer unit and run from this cable to the various lighting points, or a transformer for each lighting point also in the consumer unit ( would make for a big consumer unit).
    Then the next thing what voltage do you go for 12V ac or dc.
    What are other people's ideas and opinions on this.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
    Renovation Spain Blog
  • jpdw
    Automated Home Guru
    • Oct 2007
    • 169

    #2
    Intersting thread !

    To my mind, the best solution would probably be low-ish voltage for distribution (24? 48?), maybe still a.c. With small final step-down done in the "fitting". The possibilities for efficient lighting & control are huge.

    However, I suspect the requirement to rip-and-replace will mean things will stick with 240vac lighting circuits and larger-than-necessary "bulbs" containing all the necessary electronics, like the current crop of GU10 LEDs 'bulb'
    Last edited by jpdw; 4 August 2009, 09:24 PM.
    Jon

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    • Creagan
      Automated Home Jr Member
      • Jul 2009
      • 28

      #3
      *If* you are going for a completely new build or re-wiring, someone recommended star wiring as a default. In this case I would use a big 12/24/48v DC unit, since LEDs are DC anyway. One big one is always cheaper/more efficient than many small ones.

      The biggest problem is that incandescent lights are so much warmer than LEDs, which have a cold feel to them.

      Unless someone has found the right combination of white and amber LEDs?

      Comment

      • TimH
        Automated Home Legend
        • Feb 2004
        • 509

        #4
        Presumably fluorescent will still be permitted, comapct or otherwise, so I'm not sure it signals the end of 240V just yet...

        If forced to go LV then AC would keep the cable sizes down and either a bridge rectifier built into the lamps, or a separate one local to the fitting to feed that with DC.

        2012 isn't far away is it!

        Cheers,

        Tim.
        My Flickr Photos

        Comment

        • toscal
          Moderator
          • Oct 2005
          • 2061

          #5
          Like most legalese documents the EU directive on banning bulbs is a little hazy when it comes to certain areas. By 2016 basically any light that has a C energy rating or below will be banned. The actual wording is "taken out of circulation".
          And as for fluorescent tube lighting there is normally an LED version.
          Originally posted by Creagan View Post
          The biggest problem is that incandescent lights are so much warmer than LEDs, which have a cold feel to them.

          Unless someone has found the right combination of white and amber LEDs?
          These are available now. We have recently installed some into a classroom.
          IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
          Renovation Spain Blog

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          • Creagan
            Automated Home Jr Member
            • Jul 2009
            • 28

            #6
            Ah, but is the lights something you would install in your own home?

            I purchase a few lights some time ago, and they made us look like we were zombies, cold and very dead.

            I must admit, it was a few years back, maybe things have moved on?

            Definitely something to look into though...

            Comment

            • jpdw
              Automated Home Guru
              • Oct 2007
              • 169

              #7
              Originally posted by TimH View Post
              If forced to go LV then AC would keep the cable sizes down
              ... which would save copper & be slightly cheaper.
              Jon

              Comment

              • toscal
                Moderator
                • Oct 2005
                • 2061

                #8
                Originally posted by Creagan View Post
                Ah, but is the lights something you would install in your own home?

                I purchase a few lights some time ago, and they made us look like we were zombies, cold and very dead.

                I must admit, it was a few years back, maybe things have moved on?

                Definitely something to look into though...
                Yes I have installed them in my house. They have replaced all the outside lights. And we have a couple inside. The inside ones have replaced normal 40w incandescent bulbs. And when we redo the kitchen in a couple of months time they will be in there as well. (will post photos) At the moment at home we only replace with LED when the original bulb has blown.
                IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
                Renovation Spain Blog

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                • Nad
                  Automated Home Guru
                  • Jul 2008
                  • 145

                  #9
                  Toscal, have you found a suitable LED replacement for a 50W halogen bulb? I've been looking for a while now and haven't found anything yet.

                  Thanks.

                  Comment

                  • Martin James
                    Automated Home Lurker
                    • Aug 2009
                    • 1

                    #10
                    Mornin' all!

                    Hello everyone - new here. I found this site while googling for cable for my lighting project & it seems like it could be useful.

                    I am renovating a house in Stoke-on-Trent which, due to the dire state of the housing market at the moment, I'm going to rent out to students, (it's close to the colleges).

                    For economy and low maintenance, I'm going with all LED lighting except for outdoor PIR floods. I've ordered some samples of LED MR10 lamps and intend to lash them up in the various rooms to see how many lamps I'll need in each.

                    As this is a 'new build', I'm going with a centralized system to keep costs down. A switch-mode PS and a couple of sealed lead-acid batts in the equipment room, (used to be the pantry, will supply 24V DC to a couple of 'ring-mains', one one on each floor. I will need some odd gubbins in there - shottky diodes, trickle-charge, boost-charge etc, but that's for later. At the moment, I have to get the wiring put in because my builder is forging ahead at an amazing rate, (yes - it surprised me as well).

                    All the 12V lamps will need to be in pairs which is not a problem since at least 2 lamps will be needed anyway to deliver sufficient light and room coverage. The lamps are 'passive, (ie. contain only series strings of LEDs with only small resistors to balance out the currrent amongst the strings), and so I see no problem with wiring a couple of lamps in series.

                    I am going to install a 5A 'ring-main' on each floor. To build this, I need DC cable - red and black inner insulation. I was searching for such cable when I found this site.

                    Anyone know where I can get cable like this? The Focus/B&Q/Homebase/Wickes set only seem to want to supply mains cable

                    I'm also searching for a switching dimmer chip for a couple of the rooms. Most of those I've found want a PWM input whereas I just want a pot on the switch plate

                    Any other advice/experience/hints/snags/criticisms/beer would be gratefully received.

                    Rgds,
                    Martin

                    Comment

                    • toscal
                      Moderator
                      • Oct 2005
                      • 2061

                      #11
                      welcome to the forum Martin, have also sent you a PM.
                      We are at the moment testing some LED dimmer systems. These will either have a rotary wheel at the face plate or a special sensor which is a glowing white LED which you touch. These then control the actual dimmer. Which has a 0 to 10v input so many HA systems can control the dimmers as well.
                      Be careful with some LED modules as many are unsuitable for dimming. This is due to the internal circuitry.
                      IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
                      Renovation Spain Blog

                      Comment

                      • nickgale
                        Automated Home Jr Member
                        • Jun 2005
                        • 38

                        #12
                        I'd stick with good old mains! The new Philips Master LED GU10 7W is very impressive and part of a whole range of LED lamps, mains in and dimmable with normal leading edge dimmers. That said they aren't available at the moment due to problems with the first batch but they produce a good quality of light - around 2700K which is similar to tungsten and although the colour rendition is not quite there it's better than anything I've seen so far. They compete very well with a 35W TH MR16 lamp

                        The problem with running low voltage is that any LED with any usable light output will probably be based on 1w or 3w luxeons running at 350mA or 700mA and need to be wired in series, most power supplies for these can only run up to 10W. Lumidrives make a power supply that can dim these using a 1-10v input so a 10K pot will do this but it will not dim them fully so you still need a switch.

                        For LED's to become a credible alternative then they need to be able to be mains in and dimmable with leading edge dimmers, as that is how all houses and buildings are wired at the moment. This is starting to happen.

                        Personally I would never consider anything other than mains wiring as you could find yourself left with something obsolete very quickly

                        HTH

                        Nick

                        Comment

                        • toscal
                          Moderator
                          • Oct 2005
                          • 2061

                          #13
                          I think what LED lighting will do is make us rethink how we illuminate things. Bit like structured wiring systems made us rethink how we wire up our homes.
                          I can see in the future we won't have the need for GU10 or MR16 or MR11 type bulbs, it will be something else. And to some extent they are already here, the flexible and solid strips, the all in one units.
                          Also I think we may see a structured wiring system for power connections. That will certainly open a whole new can of worms and possibly another topic.
                          Last edited by toscal; 13 August 2009, 11:07 PM.
                          IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
                          Renovation Spain Blog

                          Comment

                          • TimH
                            Automated Home Legend
                            • Feb 2004
                            • 509

                            #14
                            I meant to reply earlier to this so sorry for the dela...

                            I don’t think I’m going to be very popular, and there are lots of issues here, but here goes…

                            “economy and low maintenance” is not a term I would readily associate with LEDs in a student let… Standard mains or LV lighting, I’d have thought, would be more the ticket. The light output from most LED lamps is (currently) realtively poor compared with their mains/LV equivalents so expect to have a lot more lamps. Those that do have higher outputs have increasing current draws (and requirement for heat dissipation) so the running cost argument is less strong.

                            What’s the ultimate plan for the property – for you to move in or sell on? There’s a thread going on the mailing list a the moment re: the “value” of automation in a house when selling and the general consensus is rather than attracting a premium, the trick is to make sure it doesn’t *detract* from its value…

                            LED lamps are usually supplied from dedicated LED driver units, rather than a run-of-the-mill SMPS so choose your power supply very carefully. What are the batteries & chargers required for?

                            I’m not an electrician, but I thought cable was cable. Where does the requirement for red & black cores come from? And how does DC cable differ from AC? Since red & black T&E is no longer acceptable in new mains wiring (even in renovations to existing properties) I think you’ll struggle to find some at a reasonable price.

                            I’d be cautious of committing to a rating for the “ring main” without calculating how many lamps you’ll need per room. If you go ahead with LEDs, you also need to ensure you identify these circuits adequately and provide proper over-current protection. A qualified electrician at this point will save you a lot of hassle later. Who’s signing off on the electrics for the house, i.e. the Part P requirement?
                            What happens if the LED fittings are replaced with a pair of standard 12V LV lights in series – instead of 5W you could have 100W. If you multiply that up for all the fittings in a room and you’ll quickly exceed the design current for the circuit.

                            I think you might be better off taking a room by room approach and if you have your heart set on LEDs, I would go with a complete system from one manufacturer. That way you know all of the bits work correctly together, and that you have a system that can be supported by someone else in the future. Color Kinetics seem to have been bought-out by Philips, but try here for some inspiration: http://www.colorkinetics.com/ls/

                            I’ve just re-read this and it all sounds a bit negative. It wasn’t supposed to be, just an identification of some of the issues.

                            Good luck with your project

                            Tim.
                            My Flickr Photos

                            Comment

                            • toscal
                              Moderator
                              • Oct 2005
                              • 2061

                              #15
                              Originally posted by TimH View Post
                              The light output from most LED lamps is (currently) realtively poor compared with their mains/LV equivalents so expect to have a lot more lamps.
                              Tim.
                              This is not true these days. Just given a demo of our 3W led GU10 bulb and the bar owner said I want 4 now and maybe another ten in a couple of months. These are easily the same output as a 25 to 35W halogen, and they really do consume 3W ( connected one up to a power meter) some manufacturers state the LED rating and not the complete power consumption of the unit. The only real down side is the smaller beam angle.
                              I hope to post some tests we are currently doing showing side by side comparisons of say a 35W Halogen and our 3W led bulbs. These will be in the form of Lux at 0.1m, at 0.5m and 1m etc type tests. This I think is better than using the Lumens that many are often quoted in as each manufacturer may use slightly different tests and equipment to get the Lumen result.
                              Last edited by toscal; 27 August 2009, 08:01 PM.
                              IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
                              Renovation Spain Blog

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