HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-grid

SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
Hi all,
I have just joined this site after I found tons of useful information just readig archived posts/threads.
First, I would like to ask the questions I haveand then below outline my intentions and items I already have in order to give you as clear a picture as possible.

Questions I would like to ask;

Is 4 mm2 twin, fire rated and shielded cable sufficient to carry enough voltage to the light circuits?
The longest cable run from battery bank to center of 8 lights (max 8A each lighting circuit) is 10 meters.

Can I reduce voltage drop by doubling or even trippling the cable at equal lengths laid parallel and joined at each end on longer runs?
I've read something about introducing magnetic activity and radio antenna symptoms.

How do I install 12v DC relays into the cable?
To minimise extra cable length (at least 5 metres extra from cable to switch), standard wall switches would activate 12v DC relays installed in the cable at the closest location to the wall switch.

Does the wiring to the relays have to be equal thickness to the cable or can it be standard wire, assuming the load using relays doesn't run to the switch & back?

Which relays should I use, NO or NC, what type & brand is recommended?

What wouldbe the fusing required for each loop, should they be located near the source or the load and can I use auto fuses for this?

Would 1200w of PV solar panels with 2 x 60A MPPT charge controllers be sufficient to charge the 12v 880Ah bank + an estimated 20% of load during charging (apr total 75A lighting + TV points, 20% = 15A + PSW inverter)?

Should I aim for a 1600W or more PV solar array?

Would such an off-grid system be expandable in future as we all know ones power needs are usually underestimated?

My intentions, info and items I already have;
I'm in Western Australia so please forgive me for using the metric system. I am an owner builder and our house is at the stage of wiring. I want to have 12 volt lighting throughout + several 12 volt points for small LCD TV's.
I already have: 112 x 12v CREE MR16 9w dimmable + beautiful 'Aztec' patterned antique brass fittings with connectors/wires, 8 x 6v/110Ah deep cycle flooded batteries Supercharge Amp-Tech (started with a cheap set as recommended by most of you forum veterans. The batteries I would parallel & serial connect to give me one bank of 12v/880AhThat's for the 12 volt, 500 meters of 4 mm2 twin, fire rated and shielded cable.
I will install a total of 112 x 12v CREE MR16 9w dimmable (consumption around 6.5 each) + 4 LCD TV points (40 watt average consumption each) as permamet fixtures but I would also like; several PSW inverter derived/powered 240 volt sockets, mainly in the kitchen to power a chest freezer-to-fridge converted refrigerator (cold food storage), 240v/800w water pump and possibly the cooker as well (looking at induction for lowest cosumption), all this in case that predicted solar activity does knock off the mains grid for a few months. You guys in the USA would probably be prepared for this possibe near-armageddon event in terms of mains grid protection, etc. but I can't see it happening in AUS; we still have a high number of pole-top fires throughout the country due to outdated technology and little money invested in maintenance. Life down under for you, mate!
The battery bank, charge controllers, battery monitor & fuse box will be housed in a fire proof enclosure 1m x 1.3m in the centre of the house on the top floor to equalise run lengths & loads; the vented-to-outside battery box at the base and all controllers, etc. above on the wall, all easily accessible for maintenance with PV array directly above on the roof. All outgoing wires/cables through floor & ceiling.
To save money while we are building (rent & travel to site) we currently live in a large shed 16 m x 7 m, insulated and plaster-boarded with full services which will eventually be the guest house. This is what most people do here on semi rural blocks. It has no windows yet so lighting is used more.
We already have a grid-connect 2.2Kw solar system and are happy with it; the last bi-monthly bill was $4 compared to the one prior to solar $280. The reason I also want an off-grid system is mostly because we can sell unused power back to the supplier at a considerably higher rate than we pay when using it. This would then hopefully pay for the off-grid system much sooner.
I have considered charging the 12v house circuit/battery bank from a mains charger overnight when our mains power cost is less then half at 11 cents and use the bank during the day to take the load of the mains circuit and return power to the grid at 47 cents. This includes government incentives for the next 9 years but could be withdrawn sooner, like some other incentives have.
Charging the bank off-grid would have the extra cost of around $2000 (PV array) as quality mains chargers are close to equal cost to solar powered charge controllers.

I would like to start wiring & ordering components within the next few days. Budget is tight, as usual during building but I think this kind of setup would be worth considering to minimise our footprint & dependency.

There will probably be more questions as I go along and I really appreciate any insight.

Kind Regards,
Sascha
«1345678

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Welcome to the forum.

    Some translations for our American friends: 4mm wire is about 12 AWG, 10 metres is roughly 33 feet.

    So let's tackle it a bit at a time and see what happens. :D

    First, this 30 metre run: will that have all eight 8 Amp lights at the end of it? Because that is really not going to work. In fact, one 8 Amp load at the end of 30 metres of 4mm is going to result in a pretty sever Voltage drop; about 7%.

    Your relay idea probably won't help much, as the relay loads and wiring will eat up power too - possibly more than the losses saved. If you were to try it, using NO relays which would be activated by a nearby switch and then turn on the light would be best. Not being able to see the whole outlay it's difficult to determine if the wiring from relay point to switch and back would be that detrimental on the load if used directly instead.

    This is one of the reasons why sometimes you just have to bite the bullet, buy the inverter, and use 120/240 VAC instead.

    I know of some small cabins that are 12 Volt wired, but a whole house? How large is it? Some of those cabins use quite large wire "looped" back to the source (both directions protected by single fuse) and tap off where needed to minimize V-drop. It isn't simple.

    The 1200 Watts of panel could run through one outback FM80 on a 12 Volt system. About 77 Amps peak, which is around 8.75% of the 880 Amp hours so that would be good. But, if you need 880 Amp hours of battery @ 12 Volts you should think about upping the system Voltage. That's over 10kW hours of stored capacity, which is better handled on a 24 or 48 Volt system.

    This is going to upset your whole plan but it has to be said: 12 Volts is not the efficient way to go. To get the same end power output you use more current over higher Voltage, and more current means more power going to heat instead of work. You need bigger wires too.

    You already have grid, so you already have AC appliances. If you want back-up PV power, skip the more expensive 12 Volt stuff and just come up with the AC Watt hours you need to supply the essentials.

    Sorry that's not the answer you were looking for, but that's the truth. The 12 Volt plan isn't very efficient or practical.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    G'Day cariboocoot and thank you for your super-speedy reply.
    I was going to translate to metric anyway and should probably have mentioned this so you can work out & post distances and wire sizes THE US way.
    The longest run would be 10 meters (not 30) and if I were to run the cable to the switch and back the total would be about 14 meters and the total would be max 8A. It's actually more like 4.5A (8 x 6.5w divided by 12 = 4.33A). the lights are quite forgiving running on lower voltage; I've tried one 12v light on a 9v battery and works fine, possibly because they are dimmable.
    If this is good I'd really like to keep at least the lighting runs on 12v but if there are severe issues I'd appreciate advice.
    I am considering putting the whole thing through an inverter and having all power at 240v.
    What size inverter should I aim for to power the above and have some extra for future additions? In case I go to 48v I would have to buy a 240v-12v transformers for all lighting runs & TV points. To simplify the system I could wire the battery bank to 48v and get the PV panels, charge controller, inverter, etc. at 48v also then hook this to the inverter and run all loads from that.
    To still be able to use the cable and keep wiring in ceilings LV, is there a suitable transformer available to power approximately 75A of 12 volt fittings, either from inverter 240v to 12v or from 48v battery bank stepped down to 12v? That is the estimated total but the fittings would never run simultaneously however, if I need to expand that in future (outdoor lights, etc.) I would prefer a transformer that could comfortably handle that.
    If I step down to 12v I'd be back to square one with voltage drops so would doubling or trippling the cables be sufficient to boost the sqmm total or would this attract other issues?
    The house is 150 sqm downstairs and 60sqm upstairs (it's simply a 60sqm two storey with lean-to's either side + 3.5m x 6m veranda & balcony front & back).
    Really appreciate your input.
    Sascha
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    PS; is this the right way to reply or should I 'reply with quote'?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Schizophrenic Canadian here; writing the number in feet and then the description as metres. :blush:

    If the total current is 8 Amps at the end of 10 metres (33 feet) you should use 8 AWG wire (which is about 8mm2) to keep V-drop below 3%, which is normally recommended.

    You could not use a 24 or 48 Volt system to power your 12 VDC devices through a transformer; transformers don't work with DC. You'd need DC to DC converters, which aren't cheap and may not be able to handle the loads. That's a thing like this: http://www.solar-electric.com/12to24or24to.html But I meant to use the higher DC Voltages to run an inverter to power everything. As I said, the 12VDC isn't very efficient.

    It is "bad practice" to parallel wire runs. The problem being that one run can develop high resistance forcing the current on to the other(s). If you do this you need to fuse each line separately according to its maximum current so that if one wire fails the other(s) can not be overloaded without the fuse blowing.

    If you were to use AC, you could still run the 12VDC things with the appropriate line power supply. If you've got 75 Amps of 12 Volt equipment that would be 900 Watts, plus any AC loads would add up to the minimum size inverter to run the lot. The other issue is the battery bank size which is dependent on how long you want to run what: the Watt hours. The 880 Amp hour 12 Volt battery could provide up to: 880 / 2 (50% DOD) = 440 * 12 Volts = 5280 Watt hours DC, about 4752 Watt hours AC. This is a pretty good amount of power on tap. My cabin uses about 1/2 that (24 Volt system) and that includes refrigerator, water pumps, computer set-up (satellite modem & VOIP phone), occasional microwave zap.

    210 sq. meters? That's pretty good size (about 2250 sq. feet). Were it me, I'd skip the 12 Volt stuff. You've got a lot of wire to run for a place that size.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Sascha, 'reply with quote ' will insert one of those blue balloons with whichever response yo want to reply to... make sense.

    as to the use of 12 v lights. most strings can be powered by an LED driver. or you can use a 220v led that avoids the V losses. just have to poke around and you will find them . Ebay is a good place to look for lots of choices.

    Simplest is get an inverter and then fit the bulbs to whatever power you have.
    As to inverter size, you need to add up all the 'loads' and estimate , liberally, the amount of time they will be 'on'. that will give you the size of inverter to get. I did mine for each hour of the day

    hth
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    If you "reply with quote" it does this:
    Sascha wrote: »
    PS; is this the right way to reply or should I 'reply with quote'?

    Fine if you want to refer to specific data in the previous post, but it can be daunting. Especially if you have to break up the post and respond to it in pieces; you have to edit in the 'QUOTE' and '/QUOTE' html tags as needed.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    westbranch wrote: »
    as to the use of 12 v lights. most strings can be powered by an LED driver. or you can use a 220v led that avoids the V losses. just have to poke around and you will find them . Ebay is a good place to look for lots of choices.

    hth

    Thanks westbranch,
    The thing is; I already have the 12v bulbs. :(
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    then you need the 'LED driver' here is a US link for what you need to look for...http://www.ledsupply.com/
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Schizophrenic Canadian here; writing the number in feet and then the description as metres. :blush:

    If the total current is 8 Amps at the end of 10 metres (33 feet) you should use 8 AWG wire (which is about 8mm2) to keep V-drop below 3%, which is normally recommended.

    You could not use a 24 or 48 Volt system to power your 12 VDC devices through a transformer; transformers don't work with DC. You'd need DC to DC converters, which aren't cheap and may not be able to handle the loads. That's a thing like this: http://www.solar-electric.com/12to24or24to.html But I meant to use the higher DC Voltages to run an inverter to power everything. As I said, the 12VDC isn't very efficient.

    It is "bad practice" to parallel wire runs. The problem being that one run can develop high resistance forcing the current on to the other(s). If you do this you need to fuse each line separately according to its maximum current so that if one wire fails the other(s) can not be overloaded without the fuse blowing.

    If you were to use AC, you could still run the 12VDC things with the appropriate line power supply. If you've got 75 Amps of 12 Volt equipment that would be 900 Watts, plus any AC loads would add up to the minimum size inverter to run the lot. The other issue is the battery bank size which is dependent on how long you want to run what: the Watt hours. The 880 Amp hour 12 Volt battery could provide up to: 880 / 2 (50% DOD) = 440 * 12 Volts = 5280 Watt hours DC, about 4752 Watt hours AC. This is a pretty good amount of power on tap. My cabin uses about 1/2 that (24 Volt system) and that includes refrigerator, water pumps, computer set-up (satellite modem & VOIP phone), occasional microwave zap.

    210 sq. meters? That's pretty good size (about 2250 sq. feet). Were it me, I'd skip the 12 Volt stuff. You've got a lot of wire to run for a place that size.

    Thanks Cariboocoot,
    I can get hold of 10mm2 wire (quad + earth, shielded) for approximately $2AUD per meter. Seems a waste to have quad but I found someone selling 150 meters for $300AUD. Is this worth considering instead of doubling the one I already have? I can always use the one I have to run power to the back of the property for a shed or similar or alternatively sell it.
    I don't want to come across as stubborn but given I already have all lights @ 12v I would still like to go ahead with 12v at least for the lighting alone, test all prior to sealing the ceilings. It looks like I started this the wrong wasy around or at least a few steps ahead of where I should have started.
    Would the 4mm2 wire be ok for shorter runs considering the bulbs work fine at lower voltage. The system being central I have several light groups near the power source. Should I run wire down to the switch and back to keep + & - within the wire the same length? One run would be critical, the stairs would have a two-way switch; base of stairs & top of stairs.
    You mentioned a cabin with wiring looped back to the source. Is this advised as opposed to running each circuit individually from the centre of the house? I know that's a lot of wire & connections.

    I'm most definitely going to run the remainng loads of an inverter since 240v appliances are widely available and cheaper than 12v or even 48v.
    If I were to have the battery bank as 48v and keep the lights as 12v would it be better to get a 240v to 12v trasformer to run of the inverter just for the lights and the remainder as a separate output from the inverter at 240v? As jou mentioned DC to DC converters are not cheap.
    I haven't done the exact maths yet but I think the 880Ah battery bank is sufficient to run an estimated load of 20-30% of the total load for quite some time.
    It's obvious to you by now that I'm not an electrician so need as much advice as possible to be able to learn as I go.
    PS; 'Love Canada and seriously considered it before we ended up in OZ.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Schizophrenic Canadian here; writing the number in feet and then the description as metres. :blush:

    I figured you meant 30ft not meters. :)
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    The 10mm2 will be a definite improvement over the 4mm2. Too bad it's quad cable, but you could run two circuits along it and "loop" it back as I described before. Whether this would be better than the individual runs depends a lot on the placement of the 12 Volt loads. The idea of the loop wiring is that it helps keep the Voltage even at all load points regardless of how much load is on the whole circuit; it will still go down, but it will be even at each "outlet".

    You could use the 4mm2 to tap off the larger wire and run to lights & their switches. It should work fine. The (+) and (-) lines do not have to be equal length because there is only one path for the current (unlike parallel battery connections).

    If you did all the wiring with standard 240VAC you could have a small power supply for 12 VDC @ the appropriate current wherever each load is. This could be a lot of little power supplies.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    here is a driver that takes 90 - 270 V AC , DC out http://www.ledsupply.com/magtech.php
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    The 10mm2 will be a definite improvement over the 4mm2. Too bad it's quad cable, but you could run two circuits along it and "loop" it back as I described before. Whether this would be better than the individual runs depends a lot on the placement of the 12 Volt loads. The idea of the loop wiring is that it helps keep the Voltage even at all load points regardless of how much load is on the whole circuit; it will still go down, but it will be even at each "outlet".

    You could use the 4mm2 to tap off the larger wire and run to lights & their switches. It should work fine. The (+) and (-) lines do not have to be equal length because there is only one path for the current (unlike parallel battery connections).

    Thanks,
    I haven't found the loop description, possibly in another post/thread, will look for it later.
    By looping do you mean return pos & neg to source? If this is the case quad would be utilised. I thought running individual circuits (about 12 of those in my case) to a central point for each lighting circuit (for example each balcony and verandah has 8 lights with the wire from the battery ending in the center of those 8 lights and then from that center each light would be wired individually with 4mm2 and the connector wire kept as short as possible.
    If you did all the wiring with standard 240VAC you could have a small power supply for 12 VDC @ the appropriate current wherever each load is. This could be a lot of little power supplies.

    Do you mean individual PSU's 240v to 12v at each center of 8 lights?

    It does get more complicated as I want to be able to have two switches for those particular 8 lights to enable me to use only the two lights in the center as low lighting and turn on the remaining 6 lights when more is needed.
    Lights are kind of spaced like this:
    o o o
    x x
    o o o
    x are the two low lighting ones and o are for the whole of balcony.
    There is an even more complicated one planned in the games room where I want to use three switches; 2 lights (low lighting) + 6 lights (max room lighting) + 8 lights (above pool table). Split into three circuits individually wired to battery/power source.

    o o o

    + + +
    x + + x
    + + +

    o o o

    x = low light, o = max room light and + is pool tabe light.
    This would look really good if it was possible to put into practice.
    I may be able to upload a PDF of my lighting plan later on so you can better understand the circuits. Please let me know if this is OK as I really appreciate your input but don't want to waste too much of your time.
    Sascha
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Sascha wrote: »
    Thanks,
    I haven't found the loop description, possibly in another post/thread, will look for it later.
    By looping do you mean return pos & neg to source?

    I only mentioned it briefly before, but yes that is the idea. The positive is then run through a single fuse to the source, so that if anything overloads the circuit one fuse blows and takes out everything. Each individual load, however, can be fused separately. It's similar to how water distribution systems are done to keep pressure even at all points (whether for a community or in some cases within a house if that house is particularly large).
    Do you mean individual PSU's 240v to 12v at each center of 8 lights?

    You could divide it up so that there were power supplies at convenient, more central locations so long as the DC wire runs were kept short and the unit was able to handle the full power demand.
    It does get more complicated as I want to be able to have two switches for those particular 8 lights to enable me to use only the two lights in the center as low lighting and turn on the remaining 6 lights when more is needed.
    Lights are kind of spaced like this:
    o o o
    x x
    o o o
    x are the two low lighting ones and o are for the whole of balcony.
    There is an even more complicated one planned in the games room where I want to use three switches; 2 lights (low lighting) + 6 lights (max room lighting) + 8 lights (above pool table). Split into three circuits individually wired to battery/power source.

    o o o

    + + +
    x + + x
    + + +

    o o o

    x = low light, o = max room light and + is pool tabe light.
    This would look really good if it was possible to put into practice.
    I may be able to upload a PDF of my lighting plan later on so you can better understand the circuits. Please let me know if this is OK as I really appreciate your input but don't want to waste too much of your time.
    Sascha

    It is still possible. You could have one 'main' switch to turn on the 12 Volt supply and then separate low-Voltage switches to adjust the lighting.

    Speaking of complicating things, how well is this plan going to go over with whatever governing body inspects and regulates your building there? I know some AHJ's who would just flat out say "no" to this proposal no matter what, because they can't wrap their heads around DC at all - much less think of it in the same place as AC. At the very least you will be required to keep the AC and DC 'separate', possibly in conduit. There's lots of things that can be done from an engineering standpoint that are definite no-nos as far as regulatory bodies are concerned.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    It is still possible. You could have one 'main' switch to turn on the 12 Volt supply and then separate low-Voltage switches to adjust the lighting.
    Any idea on how I could wire this as it is a really good suggestion?
    Would remote switching be an option or would the RC receivers take too much load for themselves to operate, most RC transmitters are independent battery operated?
    Speaking of complicating things, how well is this plan going to go over with whatever governing body inspects and regulates your building there? I know some AHJ's who would just flat out say "no" to this proposal no matter what, because they can't wrap their heads around DC at all - much less think of it in the same place as AC. At the very least you will be required to keep the AC and DC 'separate', possibly in conduit. There's lots of things that can be done from an engineering standpoint that are definite no-nos as far as regulatory bodies are concerned.
    DC domestic is relatively new here and unheard of so if I had to have it approved directly by a government/shire employed inspector they would probably reject it purely because they don't understand the concept but here we use electricians to inspect and certify domestic power. Most electricians would steer clear of DC but a friend of mine will draw out wiring plans for the 240v so I can assist him myself with installation and then he will connect all AC circuits to a sub-panel of circuit breakers and mains run-in and then certify the lot. The authorities here don't even bother coming out during main costruction stages even though they have to be notified and have the right to inspect. We employ an engineer to approve all those and then it is his responsibility in case anything is against regulatios, same goes with electricity & plumbing. By law I'm not allowed to install 240v mains & plumbing but LV is OK.
    I always overcompensate on all aspects of the building including structural integrity (extra floor joists for upstairs, thicker walls, reinforced frame structure, insulation, etc.. I'd rather have it built better and safer than barely go by regulations. AC will absolutely be kept separate from DC. I'm not running the two together in parallel, there is plenty of room to run the AC points elsewhere.
    I will most likely do what you suggested; buy the 10mm2 quad & earth cable and use my existing cable to connect the individual lights.
    By the way; how do I ground/earth the DC circuits?
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    westbranch wrote: »
    here is a driver that takes 90 - 270 V AC , DC out http://www.ledsupply.com/magtech.php

    Thanks westbranch,
    I'll look intp this. At 700mA I would need quite a few of these.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Okay understand that any info given is based on the rules and practices followed here. May not be acceptable there. Despite the reality that physics is the same everywhere, governments don't seem to understand this. :p

    Low Voltage DC circuits don't need grounding. They can't kill you. Here we're talking about a 12 Volt system that will be under 15 Volts (arc point) and fairly low current too. Every bit as safe as the wiring in your car. Well, maybe not as some cars have stupidly convoluted wiring. :p

    The AC to DC set-up is pretty straight forward. One switch controlling the AC to the power supply. Output of that would go to whatever switches you need to operate various lights up to the limit of the supply. The power supply location would have to be accessible (not sealed in a wall or crawl space) for service. The DC wiring and switching would be required to be kept separate so no one at a future date feeds 240 VAC to a 12 VDC circuit by mixing them up in a switch box. I wouldn't use RC switching unless there's a really good reason too. The receivers require power all the time to stay active.

    Any help?
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Okay understand that any info given is based on the rules and practices followed here. May not be acceptable there. Despite the reality that physics is the same everywhere, governments don't seem to understand this. :p

    Absolutely! I will be taking the much needed advice on board and turning it into practice and any consequences are solely my responsibility.
    Low Voltage DC circuits don't need grounding. They can't kill you. Here we're talking about a 12 Volt system that will be under 15 Volts (arc point) and fairly low current too. Every bit as safe as the wiring in your car. Well, maybe not as some cars have stupidly convoluted wiring. :p

    I knew (well; assumed from my understanding) that LV DV circuits don't need grounding. My head is about to explode with all the info & options mixing in there so may have asked a stupid question. :(
    I meant for lightning protection, is there any need for that providing the whole house will be grounded via earth rod, as per regulations?
    The AC to DC set-up is pretty straight forward. One switch controlling the AC to the power supply. Output of that would go to whatever switches you need to operate various lights up to the limit of the supply. The power supply location would have to be accessible (not sealed in a wall or crawl space) for service.

    Keep it simple seems to be paramount and this makes sense, totally. All AC for the house would be fed from a sub-panel downstairs, fed from the main panel located at the side of the shed which in turn is fed from the property boundary/grid. The existing 2.2kW grid connect, inverter and PV array are on the shed near the main panel (purely AC output).
    Power from the sub-panel will be supplied as a single fused run to the DC room upstairs, isolation switch inserted there before any supply in case I need to disconnect from AC for maintenace or upgrades.
    The DC wiring and switching would be required to be kept separate so no one at a future date feeds 240 VAC to a 12 VDC circuit by mixing them up in a switch box.
    I will be keeping a wiring diagram within the sub-panel and also on the inside of the DC room door, not unlike the power run-in map required by regulations to be kept inside the main grid power box at the property boundary. That map needs to show where the main underground power supply cable is located.
    I wouldn't use RC switching unless there's a really good reason too. The receivers require power all the time to stay active.
    So would NC relay switches also require constant power? I'm at a point where I'm considering using standard AC switches but I know they are not recommended as they need to be replaced frequently due to wear on contacts and also; how would I insert a 10mm2 wire into a 4mm2 terminal. :)
    Are there DC switches out there that look more like normal domestic wall switches, not so much like RV surface mount switches?
    Any help?

    Very much so! I,ve cross-referenced your advice with advice i've obtained so far and your's is by far the best in terms of explaining things and also drawing me back to basics as I do seem to drift and keep my own opinions on top and question anything not within my idea of the setup I want; stubborn I guess.
    I really appreciate all this!
    I'm now considering reducing the battery bank to 12v 660Ah because charge controllers in that range are more readily available and anything above that seems to cost more per Amp. In most instances I would need 2 x charge controllers for a 880Ah bank or fork out the extra $$. Originally I was going to just have a simple DC circuit to be powered overnight by a mains charge controller like the Victron Phoenix or Centaur range. The reason for this was to take advantage of the $0.11/unit cost overnight compared to the buy-back of $0.47/unit. I was hoping to return as many units to the grid as possible from the grid-connect solar whilst using the battery bank to power all lighting and also some frequently used appliances (water pump, cold food storage, cooking, small TV sets) through inverter during the day. This would pay for itself much sooner than the additional off-grid solar setup but would offer less or no independence. This would keep it really simple and may be the way to go for the time being and perhaps add a PV array later on. What is your opinion on that?
    I really want to have the battery bank as 48v for stability but it just gets even more mind-boggling, considering the light bulbs I already have are all 12v. To add 240v - 12v LED drivers would cost an extra $5 each. Should I sell the 12v bulbs and get 240v bulbs with on-board drivers instead or are they more prone to fail given the driver is on top of the bulb and therefore introducing some heat to the bulb?
    Running the whole lighting circuit @ 240v would definitely simplify the setup, eliminate voltage drop & other issues with DC wiring and the cost would surely be less; cheaper standard 2.5mm or 1.5mm twin & earth wiring & standard wall switches. However, I can't seem to find a suitable wall mount inverter. Most advertised online are the portable kind with two socked outlets and the charge controller/inverter combo's go into thousands $$$
  • BB.BB. Super Moderators, Administrators Posts: 29,350 admin
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    You may also want to experiment a bit with 12 VDC lighting... LED's are "non-linear" circuit elements. And a small change in voltage at the LED can make a fairly big change in lighting levels...

    This makes LED (and CFL--compact florescent lamps) lamps fairly sensitive to electrical noise in the power lines. You might try one or two LED lamps and some of your other planned loads and see if you get flickering at the lamps.

    A ballast (basically, sets the current limit to the LED/CFL instead of voltage levels like a filament lamp would use) can be as simple as a series resistor--Or a fairly complex electronic circuit that limits current flow.

    Testing before you buy a whole bunch of expensive lights would probably be helpful.

    Since you are looking at 12 volts anyway--You could probably use your car's electrical system for the testing... Engine off, 4 way flasher on, see if the LED lamp flickers. Turn on head lamps, start the car, etc... If there is annoying flicker with the car's electrical system--You might also see that with your off grid power system (pumps cycling, people turning on and off lamps, electronics, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    BB. wrote: »
    You may also want to experiment a bit with 12 VDC lighting... LED's are "non-linear" circuit elements. And a small change in voltage at the LED can make a fairly big change in lighting levels...

    This makes LED (and CFL--compact florescent lamps) lamps fairly sensitive to electrical noise in the power lines. You might try one or two LED lamps and some of your other planned loads and see if you get flickering at the lamps.

    A ballast (basically, sets the current limit to the LED/CFL instead of voltage levels like a filament lamp would use) can be as simple as a series resistor--Or a fairly complex electronic circuit that limits current flow.

    Testing before you buy a whole bunch of expensive lights would probably be helpful.

    Since you are looking at 12 volts anyway--You could probably use your car's electrical system for the testing... Engine off, 4 way flasher on, see if the LED lamp flickers. Turn on head lamps, start the car, etc... If there is annoying flicker with the car's electrical system--You might also see that with your off grid power system (pumps cycling, people turning on and off lamps, electronics, etc.).

    -Bill

    Thanks BB,
    I've tested a bulb connected to a 9v standard (the small type for fire sensors, torches, etc.) and it works fine, no flicker, good output. I guess this is due to them being dimmable so lower voltage probably wouldn't affect the 50,000 hours life expectancy of the bulbs. Still, they are designed to run @ optimum 12v so some may affect it in the long run if the voltage is permanently lower. I don't know how well they would cope on higher voltage and I can't find the technical data for this, have emailed the manufacturer but no reply yet. I am now considering. I see what you are saying in regards to items being switched on/off on the same circuit so thanks for the advice. I've pretty decided now to run a 240v supply to the center of each lighting circuit and then use LED drivers from there to the bulbs. They pretty much guarantee the max life expectancy of the bulbs since they are designed for that.
    I thought; 1 x 35w-160w LED driver for the max lighting circuit (6 bulbs) and individual 12w LED drivers for the min lighting (2 x 12w LED drivers to power 2 bulbs). While we are on this subject; could I use the higher watt rated LED drivers to power the min lighting (2 bulbs) or would the rated output wattage be too high? My understanding is that it wouldn't be too high considering the 12w LED drivers are suitable to power 9w bulbs (9w output but consumtion about 6.5w)Some of the drivers on eBay have a rating of 35w-160w and cost about the same as the individual ones.
    Kind Regards,
    Sascha
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    PS; I pretty much jumped into buying the bulbs and batteries thinking my idea of the 12v DC is good to go prior to seeking extensive advice. My bad! :(
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    I'm having a little bit "too much fun" right now so I'll try to briefly answer some of the questions.

    Yes, NC relays will sit there chewing up power when "OFF". NO relays will chew up power when "ON". Standard AC switches will actually work with low current, low Voltage DC - but they're not "rated" for it and so are technically illegal to use for that purpose. A good auto supply house may have some suitable switches with better appearance, but they won't look like standard switches.

    Can you charge the battery from an AC source and add panels later? You certainly can! I don't know how many times I've helped people set up systems like this - dozens at least. All based on "can't afford the panels now". Usually they're remote cabins and charge from a generator power something like an Iota charger or a good inverter with built-in charger. But the process is the same. The only trick is that you have to know when to turn the charger on. Some, like the Iota, can be left to handle the task on their own. Others require monitoring. Or you could rig up a simple timer to come on once a day and see through the charging cycle and then turn off so the charger isn't eating up electric unnecessarily. These chargers are not quite as good at recharging deep cycles as solar panels & controllers, even though they're made for it.

    I see no reason why you couldn't maximize your PV output by selling all its power to the grid and then buying back whatever is need to recharge the "emergency power batteries". Just remember that if the grid goes down, so does the battery recharging (without additional rewiring and fuss).

    I don't know what LED lights are available to you there. We have a limited selection here and they're all very pricey. The electric rate is so low that the payback can be very long. But I love my LED Christmas lights! :D One tenth the power of the old bulb strings, and I prefer the way they look. Can't say the same about the "standard bulb" LED's. Not yet, not here.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Can you charge the battery from an AC source and add panels later? You certainly can! I don't know how many times I've helped people set up systems like this - dozens at least. All based on "can't afford the panels now". Usually they're remote cabins and charge from a generator power something like an Iota charger or a good inverter with built-in charger. But the process is the same. The only trick is that you have to know when to turn the charger on. Some, like the Iota, can be left to handle the task on their own. Others require monitoring. Or you could rig up a simple timer to come on once a day and see through the charging cycle and then turn off so the charger isn't eating up electric unnecessarily. These chargers are not quite as good at recharging deep cycles as solar panels & controllers, even though they're made for it.
    Thanks,
    I'm thinking on the lines of this thing; http://www.photonage.com.au/advance-inverterups-pure-sine-wave-36kva-24v-input-autoswitch-p-11113.html. In case links aren't allowed I apologise, please remove if this is the case. It's a solar & mains charge controller/UPS with inverter included. This would than mean wiring my battery bank to 24v 440Ah and the 50A charge capacity should be able to charge the bank, the inverter is of reasonable output for most of my needs and the PV panels can be added later. I've already been given the same advice as your's; timer switch to make the mains charger take over at night so thanks for confirming this. I'm not too sure about it's rated 80% efficiency but I guess you get that with low cost units. The 3 stage charging is probably not the best one but I'm hoping I can manually perform an equalizing charge when required.
    I don't know what LED lights are available to you there. We have a limited selection here and they're all very pricey. The electric rate is so low that the payback can be very long. But I love my LED Christmas lights! :D One tenth the power of the old bulb strings, and I prefer the way they look. Can't say the same about the "standard bulb" LED's. Not yet, not here.

    The 9w LED bulbs have good output, comarable to 50w halogen but the beam, even though it says 60 degrees is quite narrow and leaves shaded areas between lights if not fitted closer together than halogen. I may experiment/improvise fitting some sort of diffuser which would probably affect the output slightly but broaden the angle.
    I hope the fun you are having is of the responsible and 'clean' kind, either way; fun is good. :)
  • BB.BB. Super Moderators, Administrators Posts: 29,350 admin
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Commercial links are fine when they help move the discussion forward.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Now to add a slight wrinkle to this train of thought...it may be better to use the LEDs for 'task oriented lighting' and use Halogen for 'ambient' on/off type situations. ie use the high power for short duration and the LED for longer time periods where you are stationary(reading).
    Don't forget about CFLs for longer time use also.
    hth
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    westbranch wrote: »
    Now to add a slight wrinkle to this train of thought...it may be better to use the LEDs for 'task oriented lighting' and use Halogen for 'ambient' on/off type situations. ie use the high power for short duration and the LED for longer time periods where you are stationary(reading).
    Don't forget about CFLs for longer time use also.
    hth

    Yes, we have planned for ambient lighting. We have installed conduit before the concrete slab was poured to be able to have lamps on the coffee table in the center of the family area for example. No trailing extension leads! At the same time we installed conduit for the kitchen island power points, cooker and oven.
    I've also ordered 10 meters of self adhesive LED strips (can also be nailed in place) to install under each step tread overhang. Most of these strips have 300 x LED/5 meters but I manged to get 150 x LED/5 meters and will further reduce the number by cutting and joining the strips with extensions (can be cut after every 3rd LED). One 5 meter length consumes around 0.6A which isn't much but I don't need the stairs to be too bright, just enough to make it safe if the overhead light is off and the visual effect is stunning. We can even change colours, apply flashing effects in different colours, etc. which may be good for parties but the whole strip is also dimmable. We'll probably agree that one wouldn't want to walk up and down stairs when they are strobing but the multifunction remote comes with the set. Also have under-cabinet sets of 3x 1w each for the kitchen. We'll definitely get some before Christmas for the Norfolk pine we have in front of the house, they are waterproof, virtually the same price as the non waterproof. I always wander how they make these things so cheap; just over $20AUD for 5 meters including the 44 key remote & mains adapter and free shipping from China.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Hi all,
    Does anyone know anything about UPS charge controller/inverters? I'm looking at purchasing this one: http://www.photonage.com.au/advance-inverterups-pure-sine-wave-36kva-24v-input-autoswitch-p-11113.html
    Is there anything similar out there instead?

    Also; could I use 35x-160w watt rated LED drivers to power only 2 x 12v 9w MR16 LED CREE dimmable bulbs (consume 6.5W) or would the rated output wattage be too high? My understanding is that it wouldn't be too high considering the individual 12w LED drivers are suitable to power 9w bulbs (9w output but consumtion about 6.5w)Some of the LED drivers on eBay have a rating of 35w-160w and cost about the same as the individual 12w ones. Please advice.
    Thanks
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    jeantyou wrote: »
    did this forum only allow people quating ?
    What do you mean?
    jeantyou wrote: »
    Unfortunately, most LED bulbs still aren't terribly bright, although you can buy CFLs and full out fluorescent tubes that run at 12V--you find a lot of these in campers and RVs, as well as off-grid houses / cabins / caves (just kidding on the last one, but I'd bet that there're probably some fall-out shelters that do just that...)
    This probably applies even more so to lights meant for car interiors.
    I'm not familiar with any screw-in style 120VAC to 12VDC adapters that then allow you to screw in 12V lights. And will automatically bypass when 12VDC is present instead of 120VAC. That's probably the big problem: having both 120VAC and 12VDC and expecting the lights to automatically switchover (or be able to use both).
    That said, how about having a parallel "emergency lighting" system (or even day lighting for when electricity is most expensive and lighting demands are lowest)? You could still have the 'fun' of running romex (and cutting out knockouts for electrical boxes, running wires through walls, patching drywall, etc.)

    I don't think mixing the 12v with mains power is a good idea and is against reg's. I was given a sample of a screw in type 10w LED (together with 5 free bulbs and a 1m light strip when I ordered 80 x 9w 12v LED CREE bulbs on eBay) to fit direclty into existing 120v or 240v in my case, so the driver is already fitted. Light is very good and has a good angle/spread, bulb is slightly bigger than standard incandescent (70mm x139mm). Life time is 40,000hrs and compares to a 75w incandescent. It is however of poor built quality; when I unscrewed it to try it elsewhere the thread part kept spinning so couldn't screw it in again. A drop of superglue did the job and it's as good as new again. I think it's assembled in china but the 9w bulbs use a US CREE chip alongside the rest of components made in China.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Ignore that one, Sascha; just another spammer and Niel has dealt with it. :D
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Ignore that one, Sascha; just another spammer and Niel has dealt with it. :D

    OK. Looks like the buy needs help but not the kind offered here. :)
Sign In or Register to comment.