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

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

    Different countries, different cultures, different terms! :D

    We usually just call 'em "that thing with the wires that the government made is put in, eh?" :p
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    what ever happened to gfi or gfci?
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Tell me about it. I think it's time you lot on the other side join the simple, decimal metric system 8)
    I lived in the UK for 10 years and could never get used to their 'stones' and 'feet' (stoneage). :roll:
    The UK government introduced metric at the beginning of the millenium, tried to make it illegal to qoute imperial. Butchers for example (pound of beef), to this day they are still quoting imperial and kilograms only if you ask but then you get a frown. Traditionalists! I guess it will take a whole genereations worth of time to finally convert.
    Hey guyz, i've just had my energy consumption monitor delivered and strongly recommend it. At under $140 including two extra sensors (3 phase) and delivery it's a great little gadget. Everyone should have one! I shopped around and finally found one that takes 4 daily rates into account, only thing it doesn't do is the 5th rate we have; weekend daytime flat rate. I didn't realise our electric water boiler (kettle we call it over here) uses 2000w :grr I knew they were power hungry things, normally around 1500w but at 2000w it may be time to switch to something else. My freezer-to-fridge conversion thermostat has also been delivered and I'll be installing it as soon as I get the freezer. I just need my son to spare me some time so we can go and fetch it; he gets an extra 5% off the price.
  • BB.BB. Super Moderators, Administrators Posts: 29,637 admin
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Actually, 2kW vs 1.5kW really does not matter for a grid connected home too much... The 2kW version will simply boil the water a bit quicker and both will use about the same amount of electricity in the end.

    Isn't it neat to actually measure/monitor your power usage? It makes decisions about upgrading appliances, finding things kids leave on, etc. all much more obvious and eliminates the guess work.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Canada officially went metric in 1977. But we still use a bizarre mixture of metric, Imperial, and SAE measure. I've learned and used all three in my lifetime, and it is my opinion that the metric system is greatly over-rated. It's cumbersome. Of the three, the SAE standards actually are the easiest to deal with. Which would you rather have: miles per gallon or kilometres per hundred litres? That last one just rolls off the tongue, doesn't it? :roll:

    On topic; you're starting to move forward on the project! Feels good, doesn't it? :D
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    You're right Bill! A more powerlul kettle will get the job done faster but probaly use the same amount of power as a slower kettle.
    It's great to see how much different things are using for example; when the fridge turns on it's compressor to maintain temperature or a wall oven, once the desired temp is achieved it goes right down. This monitor will enable me to calculate the pay-back for less power hungry appliances which normally cost more. If I can get a cooker that uses say 25% less power to do the same job as a standard one I'll be able to weigh up how long it takes to pay off the difference in price. I think if this is down to one year or so it's worth biting the bullet/paying a bit more initially and then reap the rewards after the time it takes to break even, given most appliances have life expectancy higher than a year. Extended warranties help ensure you get at least three years worth of savings on top of the initial period it takes to save the extra paid for a more expensive lower consumer.
    Unfortunately one can't just replace the kids in the same way:D and it takes many times to make them realise they don't need the xBox on at the same time as the PC, laptop & TV.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Which would you rather have: miles per gallon or kilometres per hundred litres? That last one just rolls off the tongue, doesn't it? :roll:

    If you mean the mouthfull of words then yes; miles per gallon sound better and it is also used here, due to a large number of former UK residents but surely, to work out measurements the metric system is much easier. I could never get my head around 3/8 of an inch or how many ounces or pounds to a stone. In metric it's all decimal; 1000 meters to a km, 1000 kg to a tonne, etc.
    On topic; you're starting to move forward on the project! Feels good, doesn't it? :D

    Absolutely! Still have to put it all into practice and it seems to take ages to get the components together, mainly international or interstate.
    On a positive note; I'm glad I didn't go out there like a bull at a gate and got all components only to realise it's not working. Your advice is well worth the wait. ;)
    We are doing the same with the rest of the house. It's taking us about two years to build but the whole thing has evolved by extensively changing the design, even the whole layout, dividing rooms, installing doors in different places, etc.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Hi all,
    I'm still waiting for most of my components to arrive:
    VICTRON MULTIPLUS INVERTER/CHARGERS PURE SINE WAVE 24V/3000W/70 AMP
    25ft 1/0 AWG wire, terminal connectors, 2 x fuse holders, hydraulic 14t crimpers

    I already have 8 x 6v/220Ah FLA batteries to be wired 4 x in series to get 24v/220Ah and then in parallel to get a 24v/440Ah bank.

    What do I need in terms of isolators, fuses, switches, ratings, etc. to connect:
    MultiPlus to mains 240v input
    MultiPlus charge controller to the battery bank and battery bank back to Multiplus inverter (I assume this is one connection)
    MultiPlus inverter 240v output to load circuit
    Bypass Multiplus from Mains 240v directly to load circuit

    Would also like to add 4 x 24v/250w mono PV panels and a charge controller for daytime charge and use Multiplus charge controller mainly at night (rate per unit from mains is less than half at night @ $0.11/unit and I can return unused units derived from already installed 2.2kW GC @ $0.47, up to a maximum of 2.2kW for the next 10 years (governmet scheme grants)).
    I am looking at the TRACKER 4215RN as a cost effective MPPT CC if it's any good, any recommendations on the controller welcome. Here is the info about this unit; http://www.epsolarpv.com/c21544/w10135149.asp

    What do I need in terms of isolators, fuses, switches, ratings, etc. to connect:
    PV panels to MPPT CC
    MPPT CC to battery bank

    Cariboocoot, you've been very helpful! I'd just like most of the advice in one place so apologise for having already asked some of the above questions. :blush:
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Not a problem.

    Can you find the manual for this thing on line somewhere? About 90% of the answers will be in that. There's nothing like getting the manufacturer's recommendation for making it easy - and keeping the warranty valid.

    Some of the other answers, like connecting to your AC for both in and out, are going to be a matter of local electrical code. We can give you generalized info on this, but not specific to either the unit or your local codes.

    For instance the AC IN is going to be 240 Volt and probably rated for the inverter output + charging capacity. 6kW max (surge) on 240 is 25 Amps, and if the charger is capable of 70 Amps @ 24 VDC that would be about another 7 Amps @ 240 VAC so the input breaker/fuse is probably rated at 40 Amps. Whereas the output would probably be the 6kW surge rating only, or a 30 Amp breaker/fuse. But that's not an absolute. Likewise if the inverter/charger needs a manual bypass (transfer switch) to take it "out of the equation" and connect loads directly to the AC supply that would be rated for at least the inverter output.

    You now know know more than you did before, which only serves to emphasize my original statement about getting the info specific to the unit. :p

    Panels. More than two parallel connections and every connection needs its own fuse. The panel will usually have a series fuse rating. Failing that you go by the Isc. When combined together you'll want at least a disconnect that will handle all of them, and preferably more circuit protection. Output of the charge controller is another circuit and requires its own protection. Best case here is to size it for the controller's maximum capacity. That way you do it once, and if it isn't "maxed out" on panels to begin with you can run it up to its full potential without having to rewire.

    There! That was no help at all, was it? :p
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Not a problem.

    Can you find the manual for this thing on line somewhere? About 90% of the answers will be in that. There's nothing like getting the manufacturer's recommendation for making it easy - and keeping the warranty valid.

    Some of the other answers, like connecting to your AC for both in and out, are going to be a matter of local electrical code. We can give you generalized info on this, but not specific to either the unit or your local codes.

    For instance the AC IN is going to be 240 Volt and probably rated for the inverter output + charging capacity. 6kW max (surge) on 240 is 25 Amps, and if the charger is capable of 70 Amps @ 24 VDC that would be about another 7 Amps @ 240 VAC so the input breaker/fuse is probably rated at 40 Amps. Whereas the output would probably be the 6kW surge rating only, or a 30 Amp breaker/fuse. But that's not an absolute. Likewise if the inverter/charger needs a manual bypass (transfer switch) to take it "out of the equation" and connect loads directly to the AC supply that would be rated for at least the inverter output.

    You now know know more than you did before, which only serves to emphasize my original statement about getting the info specific to the unit. :p

    Panels. More than two parallel connections and every connection needs its own fuse. The panel will usually have a series fuse rating. Failing that you go by the Isc. When combined together you'll want at least a disconnect that will handle all of them, and preferably more circuit protection. Output of the charge controller is another circuit and requires its own protection. Best case here is to size it for the controller's maximum capacity. That way you do it once, and if it isn't "maxed out" on panels to begin with you can run it up to its full potential without having to rewire.

    There! That was no help at all, was it? :p

    On the contrary Cariboocoot, great help! You've confirmed my assumed breaker ratings.
    I know local code won't allow me to install most of the above but out of curiousity; did you install your setup yourself or hire a qualified sparky? Are you a qu alified sparky? I'd like to do most of the work myself and then, before installing wall coverings have it checked and approved by a qualified person, someone I know has agreed to do this but may have limited knowledge of DC. I want to get all the components myself and have the system exceed local code requirements in terms of safety, just to be on the safe side. Perhaps combine all standards and go above. I'm sure your local code (standards) will probably be more detailed than AUS or local Western Australian standards.
    Did you have a chance to glance over the Tracker 4215RN? I know an OB charge controller is what you'd probably recommend but there is a fair difference in cost.
    Are there any general references available as to what I need to complete a solar PV to battery bank charge controller installation, wiring & fusing, since the PV, charge controller & bank will be bought from different suppliers?
    Another thing I came across, most probably on this site, is one of the moderators advising a separate smaller inverter for the smaller loads like lighting and use the MultiPlus inverter for a few of the larger loads, because larger inverters consume more of the precious battery power than smaller ones. If I install a 600w inverter just for the lights (total around 700w but never on all at once, maybe around 30% max lights used simultaneously at anyone time) would that make a big difference on the power needed to invert?
    You are of great help and I appreciate your time and advice on this so I keep pressing the 'refresh' button, eager to get your reply as soon as you submit it.:D
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    I'm a semi-retired Mad Scientist who lives in the Great White North. There are no inspections in Cabin Country, so everything is done by "good practice". Or in some cases by "so incredibly wrong it's unbelievable the place hasn't burned down" practice. That's usually when I'm loading the van with the latest batch of scrap batteries. :p

    NAWS has one book on their recommended list: http://www.solar-electric.com/bonewsoelho.html
    I haven't read or reviewed it or any other, as I'm supposed to know what I'm doing already. If it weren't for slightly erratic brain function from time to time I probably would.

    The best hint I can give you is to mentally divide the system into its individual circuits and study them one at a time. For instance there are two AC circuits: AC IN and AC OUT. Here's what it would be like here:

    AC IN: 40 Amp 240 VAC breaker in the main panel feeding 8 AWG wire to the inverter.
    AC OUT: 10 AWG wire feeding a sub panel with a 30 AMP main breaker. Then we could divide that up in several ways including four 15 Amp 120 VAC circuits or one 20 Amp 120 VAC and two 15 Amp ones or one 20 Amp 240 VAC and two 15 Amp 120. Et cetera. Since you use 240 VAC directly there, I suspect you have only two 15 Amp 240 VAC circuits available?

    The main difference between our two countries in this is going to be your use of metric sized wire, which is slightly different size and therefor has slightly different Ampacity. The insulation may have different qualities (rating) as well. With current it's all about being able to dissipate heat, which is why the ratings go down for wire in conduit. Here wiring can be exposed (but secured) if it's not in "living space" (i.e. unfinished basement or garage). If it's living space it has to be "inaccessible" (behind wall or in conduit). This is ironic because all connections must be accessible. See why interpretation of the rules can start arguments?

    Then there are your DC circuits: PV to charge controller, controller to battery, and battery to inverter.
    The PV to controller circuit is going to be most critical for wire sizing as it is usually the longest run of the lowest Voltage. Normally if you have more than two strings (and in this case a "string" can be one or more panels in series) you would use a combiner box with either fuses or breakers rated for the "series fuse" recommended by the panel maker. If there is no recommended size, the number will be between Isc and 2 * Isc so that the protection will trip if one string shorts and is fed > Isc by the other two (or more) strings. From there the wiring has to handle the combined current @ Voltage for the run to the charge controller. Usually this line will have at least a disconnect and more often a breaker which offers circuit protection and disconnect ability. Some areas require specialized breakers and disconnects (following NEC's new DC GFI rules and accessible to firemen outside the building). Depending on the exact panel layout it may be necessary to include the panel to combiner wire length in the V-drop calculations. Clear as mud?

    The controller to battery is probably the simplest. Make sure the wire can carry the full current and is also large enough to keep V-drop to a minimum. If it isn't, the controller can get false battery Voltage readings and not function correctly. Some controllers have separate battery Voltage sensor wires. Again this wire will have its own breaker or fuse (the breaker allows easy disconnect; you might want to add a separate disconnect with a fuse).

    Then there's the battery to inverter wiring. This is going to be the heaviest gauge as it will carry the most current and also needs to minimize V-drop so the inverter doesn't read "incorrect" Voltage and shut down because it thinks it's too low. Again it needs circuit protection and a disconnect. If there are two or more battery strings each should have its own fuse in addition to the inverter fuse/breaker.

    The two inverter trick is common in off-grid applications. Big inverters will use 20+ Watts just doing nothing. In standby mode they might use 6 Watts - doing nothing. A Morningstar 300 will use 6 Watts supplying 300 Watts, and less than 1 while waiting for a load to turn on. When you're running everything off batteries, inverter consumption can be a real issue: 20 Watts * 24 hours = 480 additional Watt hours that has to be supplied. Where this doesn't work is if you have repeat or frequent high loads, like a refrigerator coming on 20 minutes out of every hour and nailing 1kW + every time it does. If the heavy loads are occasional and controllable (not thermostat dependent for instance) then shutting off the big inverter when not needed is a good plan.

    The only thing I can say about the Tracer controller is that its specs would indicate it is a true MPPT controller. Quality? You have to find someone who has already risked his money. Maybe post an inquiry under the product review section and see what others think.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    I'm a semi-retired Mad Scientist who lives in the Great White North. There are no inspections in Cabin Country, so everything is done by "good practice". Or in some cases by "so incredibly wrong it's unbelievable the place hasn't burned down" practice. That's usually when I'm loading the van with the latest batch of scrap batteries.

    I'm heading the same way in terms of Mad Scientist, hopefully I can sustain all the advice you are providing here and put it into practice and who knows, maybe one day pass it on if I'm confident enough I wouldn't endanger the recipient.
    The best hint I can give you is to mentally divide the system into its individual circuits and study them one at a time. For instance there are two AC circuits: AC IN and AC OUT. Here's what it would be like here:

    Great advice! I was more inclined towards getting it all on one page and then splitting it down onto a sequence numbered 'to do list'
    AC IN: 40 Amp 240 VAC breaker in the main panel feeding 8 AWG wire to the inverter.
    AC OUT: 10 AWG wire feeding a sub panel with a 30 AMP main breaker. Then we could divide that up in several ways including four 15 Amp 120 VAC circuits or one 20 Amp 120 VAC and two 15 Amp ones or one 20 Amp 240 VAC and two 15 Amp 120. Et cetera. Since you use 240 VAC directly there, I suspect you have only two 15 Amp 240 VAC circuits available?

    I will output into 2 x 15A/240VAC. Would 10AWG (2.5mm2) wire be underpowered to feed the main to inverter? The 10AWG is commonly available for main domestic circuits.
    The main difference between our two countries in this is going to be your use of metric sized wire, which is slightly different size and therefor has slightly different Ampacity. The insulation may have different qualities (rating) as well. With current it's all about being able to dissipate heat, which is why the ratings go down for wire in conduit. Here wiring can be exposed (but secured) if it's not in "living space" (i.e. unfinished basement or garage). If it's living space it has to be "inaccessible" (behind wall or in conduit). This is ironic because all connections must be accessible. See why interpretation of the rules can start arguments?

    All my circuits will be inside the wall and above ceilings, behind plasterboards & insulation. The insulation is non combustible (EarthWool) and the wiring in walls would only be touching it on one side with approx. 10mm cavity space on the other side. In the ceilings the wiring would be secured on cross members above the insulation. All wiring would be insulated twin & earth; 10AWG to sockets and 14-15AWG for lighting as per regulations. I may use 10AWG for the lighting circuits so I can run 4 points to power 30w max LCD TV sets, two sets on each lighting circuit. This may not be within the reg's but given the points will only ever power 30w appliances there hopefully shouldn't be an issue with overloading the circuit, especially not 10AWG wiring. For the sake of around $50 difference in price between 10AWG and 14-15AWG I may as well do all in 10AWG. Are there any downsides in running a 10AWG lighting circuit other than wire size where I will have to make sure the terminals can take the thicker wire?
    I have a roll of 14-15AWG which I can use for lighting switches and 6 x interconnected smoke sensors.
    Are there any issues with connecting 14-15AWG switches/wiring to a 10AWG lighting wire?
    Then there are your DC circuits: PV to charge controller, controller to battery, and battery to inverter.
    The PV to controller circuit is going to be most critical for wire sizing as it is usually the longest run of the lowest Voltage. Normally if you have more than two strings (and in this case a "string" can be one or more panels in series) you would use a combiner box with either fuses or breakers rated for the "series fuse" recommended by the panel maker. If there is no recommended size, the number will be between Isc and 2 * Isc so that the protection will trip if one string shorts and is fed > Isc by the other two (or more) strings. From there the wiring has to handle the combined current @ Voltage for the run to the charge controller. Usually this line will have at least a disconnect and more often a breaker which offers circuit protection and disconnect ability. Some areas require specialized breakers and disconnects (following NEC's new DC GFI rules and accessible to firemen outside the building). Depending on the exact panel layout it may be necessary to include the panel to combiner wire length in the V-drop calculations. Clear as mud?

    I assume for 24v/1000w PV, 0AWG is sufficient and the rest is too much to take in right now so will worry about it after the multiplus is up and running!?:confused:
    The controller to battery is probably the simplest. Make sure the wire can carry the full current and is also large enough to keep V-drop to a minimum. If it isn't, the controller can get false battery Voltage readings and not function correctly. Some controllers have separate battery Voltage sensor wires. Again this wire will have its own breaker or fuse (the breaker allows easy disconnect; you might want to add a separate disconnect with a fuse).

    Then there's the battery to inverter wiring. This is going to be the heaviest gauge as it will carry the most current and also needs to minimize V-drop so the inverter doesn't read "incorrect" Voltage and shut down because it thinks it's too low. Again it needs circuit protection and a disconnect. If there are two or more battery strings each should have its own fuse in addition to the inverter fuse/breaker.

    Again, I assume 0AWG is sufficient!?
    The two inverter trick is common in off-grid applications. Big inverters will use 20+ Watts just doing nothing. In standby mode they might use 6 Watts - doing nothing. A Morningstar 300 will use 6 Watts supplying 300 Watts, and less than 1 while waiting for a load to turn on. When you're running everything off batteries, inverter consumption can be a real issue: 20 Watts * 24 hours = 480 additional Watt hours that has to be supplied. Where this doesn't work is if you have repeat or frequent high loads, like a refrigerator coming on 20 minutes out of every hour and nailing 1kW + every time it does. If the heavy loads are occasional and controllable (not thermostat dependent for instance) then shutting off the big inverter when not needed is a good plan.

    I have installed one of those freezer-to-fridge thermostats which comes on for around a minute or so every hour to maintain 4-6 degrees celsius. Freezer specs: Rated current = 0.6A, input power = 115W, energy consumption = 0.85kWh/24 hours,
    I can ignore the latter one (0.85kWh/24), since it's running on 0 stand-by power; the thermostat is powered by an internal battery which recharges whenever the fridge comes on to maintain temp. but also has the option to run on standby if battery needs extra charge and also full disconnect when away for longer periods:cool: I'd highly recommend this thermostat if you're willing to sacrifice the convenience of an upright fridge where everything is on display as soon as you open the door. That's unfortunately when most of the cold is lost. I was amazed at the simplicity of this idea; hot air rises and cold air goes down, dah! :roll: Claims to be able to run on approx. $4 a year so the $150 for the thermostat is regained within the warranty period of the freezer. No modifications are done to the freezer as the temp. sensor is inserted through the drain pipe at the bottom of the freezer. You do howewer need to remove any condensation every few months or so for hygene so putting a tray on stilts at the bottom of the unit is advised.
    I think this should be perfectly safe and not considered as a high consumer, perhaps run a dedicated small inverter directly from the battery bank for that?
    The only thing I can say about the Tracer controller is that its specs would indicate it is a true MPPT controller. Quality? You have to find someone who has already risked his money. Maybe post an inquiry under the product review section and see what others think.

    Well put Cariboocoot! I'll probably end up being the one risking my money to see if it's any good. Worth risking under $300?:grr

    PS; You are a genius and a great asset to this site alongside other moderators or members sharing their experiences with others! Aren't I lucky I stumbled upon this site???:D
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    The thing about wire sizes ...
    Will 10 AWG work with standard switches and outlets? Good luck getting the wire on the terminals. Even 12 AWG is a struggle.

    What size wire you use for any given circuit depends on two things: the current expected and the length of the run which will affect the Voltage at the other end (the dreaded V-drop). The "good practice" rating for AC circuits is like this:
    15 Amp circuit = 14 AWG wire, 20 Amp circuit = 12 AWG wire, 30 Amp circuit = 10 AWG, 50 Amp circuit = 8 AWG

    You can find a lot of chart listing Ampacity of different wire gauges. You will find they disagree somewhat too. This is the fun of interpretation.

    1000 Watts on 24 Volts is roughly 42 Amps. 4 AWG will handle those Amps, but at about 66% of its capacity. Then there's the Voltage drop issue. In this case it isn't much: 4 AWG will handle 42 Amps @ 24 Volts for up to 30 feet before the V-drop goes over 3% (rough calculation here). Bigger wire (0 AWG you mentioned) will work, but costs more. The thing with the inverter is that it's 3kW @ 24 Volts or 125 Amps. With the same 4 AWG the run has to be shortened to 10 feet to keep the V-drop down.

    This is why we always try to run large arrays at high Voltage and use the MPPT advantage to achieve charging levels: higher Voltage = lower current for the same over-all power, and the Voltage is what overcomes the wiring resistance.

    An array example: 1200 Watt array 30 feet from charge controller.
    1200 Watts @ 24 Volts = 50 Amps. Wire size 4 AWG, V-drop 3%+
    1200 Watts @ 48 Volts = 25 Amps. Wire size 10 AWG V-drop 3%+

    Big savings on wire there. And with a good MPPT controller you could theoretically go even higher in Voltage on the array:
    1200 Watts @ 120 Volts = 10 Amps. Wire size 14 AWG, V-drop < 2%

    BTW, a Morningstar 60 Amp MPPT is about $500 in the States. The Outback FM60 roughly $20 more. The MidNite Classic $100 over that. The OB and MidNite include metering that MS charged another $90 for.

    WARNING: There is a very fine line between 'genius' and 'madness'! :p

    This forum keeps my aging brain exercised.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    The thing about wire sizes ...
    Will 10 AWG work with standard switches and outlets? Good luck getting the wire on the terminals. Even 12 AWG is a struggle.

    Hi Cariboocoot,
    Please correct me if I'm wrong. We are using 2.5mm insulated twin & earth wire in white sheath in Australia (ISO standard) for standard domestic ring or radial circuits and 1.5mm insulated twin & earth wire in white sheath for lighting circuits. I've converted that to AWG for you in my previous reply and now have spent the last half hour or so trying to find references as to what the 2.5mm in Australian standard mains wiring stands for. I've also measured the cross section of a standard light switch which is approx. 3.5mm2 which doesn't make sense because a 2.5mm wire needs a cross section of 4.9087mm2. :confused:
    Am I safe to assume that 2.5mm stands for the cross section and not diameter? This would make our 2.5mm standard roughly 13 AWG.
    To make it more complicated, I know auto wiring sometimes includes the insulation/plastic around the copper within the AWG total.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Like Einstein said "I never remember what I can look up".

    http://www.engineeringtoolbox.com/awg-wire-gauge-d_731.html

    I think you're getting the diameter and cross-section (area) confused.
    2.5mm2 is the area (Pi*r^2) of a wire with a diameter of about 1.78mm. This is in between 14 AWG and 13 AWG.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    I'm glad we've sorted that one!
    Initially I thought the mm measrement of a 2.5mm cable (actually called 2.5mm mains cable) would simply translate into AWG. I bow to you 'non-metric' lot on this one.:blush: At least your AWG is simplified compared to our mm cable sizes, the only thing wrong with it; it's back to front! In my opinion the higher AWG number should translate into thicker cable. :grr
    AC IN: 40 Amp 240 VAC breaker in the main panel feeding 8 AWG wire to the inverter.
    AC OUT: 10 AWG wire feeding a sub panel with a 30 AMP main breaker. Then we could divide that up in several ways including four 15 Amp 120 VAC circuits or one 20 Amp 120 VAC and two 15 Amp ones or one 20 Amp 240 VAC and two 15 Amp 120. Et cetera. Since you use 240 VAC directly there, I suspect you have only two 15 Amp 240 VAC circuits available?

    AC IN: This would then be about 8mm in our terms but the installation manual says ' use 2.5mm2 or 4.5mm2' (14-11 AWG)? The technical guru from Victron even suggested I fit a standard plug to the input wire and plug it into a simple timer to enable automatic activation at 9 pm.
    is this a bit under-rated?
    AC OUT: I have some 4mm cable (about 11 AWG), will this be sufficient?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Sascha wrote: »
    I'm glad we've sorted that one!
    Initially I thought the mm measrement of a 2.5mm cable (actually called 2.5mm mains cable) would simply translate into AWG. I bow to you 'non-metric' lot on this one.:blush: At least your AWG is simplified compared to our mm cable sizes, the only thing wrong with it; it's back to front! In my opinion the higher AWG number should translate into thicker cable. :grr

    You want to know why it's backwards? Because it's based on the length of wire that can be drawn from a given volume of raw material. The thinner the wire is, the more feet of it you get from your pound of copper. That bit of useless old trivia is brought to you by the same people who did the same thing with shotgun gauges. :D
    AC IN: This would then be about 8mm in our terms but the installation manual says ' use 2.5mm2 or 4.5mm2' (14-11 AWG)? The technical guru from Victron even suggested I fit a standard plug to the input wire and plug it into a simple timer to enable automatic activation at 9 pm.
    is this a bit under-rated?
    AC OUT: I have some 4mm cable (about 11 AWG), will this be sufficient?

    We have to be clear on what the expected current is in order to get the wire sizes right. 4.5mm2 is between 11 AWG and 10 AWG and ought to be good for roughly 30 Amps. That's 7200 Watts on 240 VAC. If this is all that's needed to handle the inverter output (loads) and battery charging it will work. Some of the variance here is due to the surge rating on the inverter; since it is not continuous you can actually use wire at a higher current rating for a short duration. They may be figuring on the 3kW continuous rating + the battery charging (1680 Watts I think it was) comes to about 20 Amps, and that would just about work on 2.5mm2. See? It all depends on how you figure it. Unfortunately there are a lot of ways to figure it. The 4mm2 should be more than enough for the output as well.

    The most important thing is that the circuit protection on these lines must be the "weak point" in terms of Ampacity. You want the fuse to blow or breaker to trip before the wire heats up and ignites the insulation. So we're back to the question of what is the current rating specs for the IN and OUT on this inverter?
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    The most important thing is that the circuit protection on these lines must be the "weak point" in terms of Ampacity. You want the fuse to blow or breaker to trip before the wire heats up and ignites the insulation. So we're back to the question of what is the current rating specs for the IN and OUT on this inverter?

    I'm sorry to be dumping this on you but you being the qualified Mad Scientist as opposed to me (not qualified) you may be able to translate this for me. Specs: http://www.ysebaert.be/index.php?id=1218&language=3
    I understand the purpose of circuit protection where the fuse or breaker has to be the weakest point to avoid frying the circuit.
    As I understand the AC input can be taken from a standard domestic circuit if the tech suggested fitting a standard plug?
    I see now what installers are charging an 'arm and a leg' for. things get complicated with only basic knowledge.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    The output using my basic understanding should require a max of 26.1 amps (peak 6000 divided by 230 = 26.0869) so the 4mm cable may be too thin considering the fuse or breaker should be greater than the current(lets say 30 amp) and 4mm cable can only carry current upto 25 amps.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    I've been digging through the manual in search of a well-hidden answer. This is what I found:

    "AC input current limit 30A or 16A depending on model"

    There is also mention of a 16 Amp transfer switch, so we can probably presume that is the maximum input load (16 * 240 = 3840 Watts). There are also two models, one has a limit of up to 30 Amps (selectable). That one is probably more money. It also explains the two different wire sizes mentioned before: 2.5mm2 for the 16 Amp model and 4.5mm2 for the 30 Amp model.

    There doesn't seem to be any mention of how long it can sustain its surge capacity of 6kW, so you should probably not count on it being available for more than a few seconds at best. In that case the wiring and circuit protection would be based on the 16 Amp rating. That means the 2.5mm2 would be usable for output and probably input as well.
  • solar_davesolar_dave Solar Expert Posts: 2,344 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Just curious, do those ring circuits get calculated the same way? Since the load is fed from 2 directions what would the fuse rating be?
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    solar_dave wrote: »
    Just curious, do those ring circuits get calculated the same way? Since the load is fed from 2 directions what would the fuse rating be?

    Hi solar_dave,
    The fuse rating is the same. There are pro's and con's to both; ring & radial, here are some pro's and con's of the ring circuit, FAULT CONDITIONS ARE NOT APPARENT WHEN IN USE: http://en.wikipedia.org/wiki/Ring_circuit .
    It does have advantages though if installed correctly like; The current to any one socket/outlet has 2 parallel paths to take, so the cable is under less load.

    Read more: What are advantages and disadvantages of ring and radial systems | Answerbag http://www.answerbag.com/q_view/422081#ixzz1vNbCD8RO .
    They are mainly used in the UK, permitted in AUS and for your country you'd have to check reg's. They are good for longer runs but in most cases require more wire. Long runs' issues for radial circuits can be remedied by using thicker wire so I guess final cost is more or less the same on longer runs. I'm having two ring circuits installed in our two storey house. Some more reference on this; http://www.answerbag.com/q_view/422081 .
    I'd disagree with the statement a ring requires double the cable. If you carefully plan a ring you're only using extra wire from your last point back to the input. Radial circuits sometimes do a near full circle if laid mainly against outer walls. You can also eliminate spurs from the circuit but any path say from an outer wall into the room would require double the wire as you'd run it to that power point and then back to continue against the outer wall. If the extra cable is an issue one is permitted to install a limited number of spurs.
    I hope this helps but if you want to get deeper into it just google 'ring vs radial circuit' or similar. :cool:
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    I've been digging through the manual in search of a well-hidden answer. This is what I found:

    "AC input current limit 30A or 16A depending on model"

    There is also mention of a 16 Amp transfer switch, so we can probably presume that is the maximum input load (16 * 240 = 3840 Watts). There are also two models, one has a limit of up to 30 Amps (selectable). That one is probably more money. It also explains the two different wire sizes mentioned before: 2.5mm2 for the 16 Amp model and 4.5mm2 for the 30 Amp model.

    There doesn't seem to be any mention of how long it can sustain its surge capacity of 6kW, so you should probably not count on it being available for more than a few seconds at best. In that case the wiring and circuit protection would be based on the 16 Amp rating. That means the 2.5mm2 would be usable for output and probably input as well.

    Thanks for digging Cariboocoot,
    The unit I'm getting is 16 amp AC, the photo of spec panel is attached and the link to the installation manual is here if you fancy doing some more digging; http://www.victronenergy.com/upload/documents/Manual%20-%20MultiPlus%203k%20230V%20Ve.Bus%20enabled%20-%20rev%2000%20-%20EN%20NL.pdf
    I've looked for the 6000w peak sustainability but no joy. :cry:
    Peak with most inverters is normally just for appliances with higher startup demand, am I right?
    There is also a 50 amp model available now besides the 16 and 30.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    BTW, a Morningstar 60 Amp MPPT is about $500 in the States. The Outback FM60 roughly $20 more. The MidNite Classic $100 over that. The OB and MidNite include metering that MS charged another $90 for.

    WARNING: There is a very fine line between 'genius' and 'madness'! :p

    This forum keeps my aging brain exercised.

    So you, recommend the Morningstar as entry level?
    I can get one shipped, lowest price I found is here: http://www.ebay.com.au/itm/Morningstar-Tristar-MPPT-60A-Solar-Charge-Controller-TS-MPPT-60-/130690355449?pt=LH_DefaultDomain_0&hash=item1e6dc090f9
    I should really stretch the budget and go for something tried & tested or recommended rather than be the first one to try it!

    PS; I think you're more of a genius than mad but to compromise; The Mad Scientist kind of sounds best! :D
  • solarvicsolarvic Solar Expert Posts: 1,053 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Why not purchase your charge controler from Arizona wind and sun, the sponsor of this forum where you got all your help? They have the charge controler on sale for $500.00 which is less money than the co. you want to buy from Ebay. I see that they sell into 60 countrys besides canada and usa. :Dsolarvic:D
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Shipping costs may be a concern here, as it is a long way to Australia from the U.S.

    Otherwise, the $519 US they want for the MS would buy the Outback from NAWS - and it has the meter in it already.

    Definitely worth comparing the shipping and duties/taxes on.
  • solarvicsolarvic Solar Expert Posts: 1,053 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Mark, The ebay seller is from California so shipping should be the same. The USPS priority box you ship in is priced the same from any location from USA. Dutys and taxed should be the same. I have bought satelite equipment from a dealer in Canada who uses Canada Post which I think might be similar to the us priority mail and I never had to pay any duty or brokerage fees, just charged me the provincial sales tax and the canadian national sales tax. One time He sent me something thru UPS and that is where I got charged the duty and brokerage fee. I just like to see people buy from our sponsor if they can especially if they might even save a few bucks. I know most of us probably look for bargains and anyone is pk to buy from anyone they want. I recently bought a new fronius inverter for $1350.00 that has a list price of about $2800.00. After I got it I see why the price was lower. It was built in 2008 so has lost 3 years of its warranty as I understand rhat Fronuis starts the warranty from build date. But for the price I can take the chance. I think I fryed the warranty already on one of my other fronuis inverters because it is recorded 647 volt. If you excede 600 v it voids the warranty. So far inverter is working ok. It just wouldn.t finish its bootup and gave me the indiation ov overvoltage. :Dsolarvic:D
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Vic;

    We Canadians know about the evil of UPS. Never did hear how that lawsuit against them came out (if it has yet).
    Using the postal services between the two countries is usually the best route for not getting ripped on "import fees".

    If this E-bay AU seller is actually shipping out of Calif, then it's a no-brainer to buy the Outback for the same money from NAWS! Better controller, better bargain, and a couple of pennies at least will go to keeping this site up. :D
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    I looked in the NAWS online shop first, of course; the shipping is extortionate though!?
    OB Flexmax 60 MPPT, NAWS shipping to here is $212.41, eBay shipping to here is $148 (USPS)
    MS TriStar 60 MPPT, NAWS shipping to here is $165.31, eBay shipping to here is $59 (USPS)
    We don't pay any import duty nor tax for items upto $1000, which is great. They've simplified the tax system here a few years ago; small business depreciations are another example; you can depreciate capital items upto $1000 right away to it's full value.
    I'd love to buy the Flexmax from NAWS but is there any way of finding out if shipping cost can be reduced. Shipping would be to Cardup, Western Australia 6122.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    If this E-bay AU seller is actually shipping out of Calif, then it's a no-brainer to buy the Outback for the same money from NAWS! Better controller, better bargain, and a couple of pennies at least will go to keeping this site up. :D

    I'd love to spend my pennies with NAWS because this site is the best reference site for solar, batteries, etc. I've come across. If they had some flexibility on using USPS for example the same pennies would still roll into the NAWS cash register. I'm not asking for them to discount the item, just post in a different way.
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