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

    Now that's progress: money that can carry itself around! :D
    Sure it's always bounding away from you (what currency doesn't?), but what other denomination can go so far these days?
    The biggest problem is folding the euros up so they'll fit in your wallaby.

    And if I make one more bad pun about this I'm going to have to ban myself.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Okay, battery fuse ratings: how much does the inverter require in fuse capacity? The individual battery fuses must be at least 1/2 that and up to the full capacity.
    The charge controller breaker/fuse needs to be rated for its output. A 60 Amp controller would have an 80 Amp circuit protector (if there isn't a specific manufacturer's recommendation).
    When you have batteries connected to a bus bar or common point, that is where the inverter and charge controller connect as well (hence the term common point).

    Hi Marc,
    The Multiplus has a 300A mega fuse from the positive M8 battery terminal connector to the inverter part. So can I use 200A fuses on each string and would the breaker switch after the parallel bus then have to be 400A DC rated?
    Does the charge controller output need separate circuit protection and how would I do that given the unit only has one set of terminals for battery connection, I can't separate the DC IN & OUT?
    The 240v AC IN has a 16A breaker built in, accessible from the front panel. Should the AC out breaker/switch be rated the same or would the current AC OUT be higher? What should the AC OUT breaker rating be for 3000w continuous, 6000w peak?
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    The biggest problem is folding the euros up so they'll fit in your wallaby.

    Haha, love this one, you could get more than $110 an hour as a comedian! ;)
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Sascha wrote: »
    Hi Marc,
    The Multiplus has a 300A mega fuse from the positive M8 battery terminal connector to the inverter part. So can I use 200A fuses on each string and would the breaker switch after the parallel bus then have to be 400A DC rated?

    The inverter's fuse rating is 300 Amps. If you put individual battery string fuses in for two strings they would be at least 150 Amps and not more than 300 Amps. Any disconnect needs to be rated for over 300 Amps (like the 350 Amp Blue Sea battery switch).
    Does the charge controller output need separate circuit protection and how would I do that given the unit only has one set of terminals for battery connection, I can't separate the DC IN & OUT?

    :confused:I've never seen a charge controller with only one set of terminals on it. It should have one pair for DC IN from the array and another for DC OUT to the batteries. The DC OUT to the batteries needs its own circuit protection, rated as per the controller's maximum. This would be on the positive line between the controller and the battery bus bar/common connection point along with a disconnect (one reason for using a breaker: circuit protection and disconnect in one).
    The 240v AC IN has a 16A breaker built in, accessible from the front panel. Should the AC out breaker/switch be rated the same or would the current AC OUT be higher? What should the AC OUT breaker rating be for 3000w continuous, 6000w peak?

    The AC OUT will invariably be lower, as the AC IN has to include allotment for the inverter's charge function. 3000 Watts on 240 Volts is 12.5 Amps. Using the NEC mark up rules that's a 20 Amp breaker. The 16 Amp input, by the same rules, would want a 30 Amp breaker. However, I strongly suggest you check your local codes on this. The Code of Good Practice we use here in the frozen wastelands would have 20 Amp breaker on the input and 15 on the output. If anyone complains, we have a complaint department: see Mr. G. Bear.

    I shall now retire from consulting and go on the road with my act. :p
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Sascha wrote: »
    Kangarros have now been superseeded by Euro's..., proper, Australian Euro's! http://ezinearticles.com/?The-Euro-is-a-Small-Kangaroo&id=3840768
    :D


    BUT who knows if the Euro's and Wallaroo's taste the same as a real 'Roo:confused::confused:
    Only the Shadow do!:-)
     
    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: »
    BUT who knows if the Euro's and Wallaroo's taste the same as a real 'Roo:confused::confused:
    Only the Shadow do!:-)

    Taste? You wouldn't eat dollars now would you? ;)
    Shadow..., yeah, they can eat what they like. I'm sure if everyone was going to switch diet and start eating roo the government would start taxing it heavily, like they do with everything once it becomes popular. Kangaroo is actually not bad to eat, personally I'm not a big fan but it's extremely low in fat. You can buy roo-burgers and bangers (sausage) in pretty much every store here.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Yes, we had 'Roo at a BarBee when we visited Oz a while back, when down for a wedding, not connected with the 'Roo feed.. it's much like wild game meat here (which can be a bit of a delicacy at times as less plentiful than 'Roo).

    cheers
     
    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
    I shall now retire from consulting and go on the road with my act. :p

    I hope you haven't packed for your road trip yet, I still need ya!:cry:
    I think you should start at the local pub and work your way up from there...., hitting the road is a no-no!:grr
    The inverter's fuse rating is 300 Amps. If you put individual battery string fuses in for two strings they would be at least 150 Amps and not more than 300 Amps. Any disconnect needs to be rated for over 300 Amps (like the 350 Amp Blue Sea battery switch).

    That's good, I can use the 200A fuses that came with the fuse holders, on each string.
    :confused:I've never seen a charge controller with only one set of terminals on it. It should have one pair for DC IN from the array and another for DC OUT to the batteries. The DC OUT to the batteries needs its own circuit protection, rated as per the controller's maximum. This would be on the positive line between the controller and the battery bus bar/common connection point along with a disconnect (one reason for using a breaker: circuit protection and disconnect in one).

    According to the manual it has auto switching. By the way; it's not a solar charge controller, it's a UPS, mains charge controller, inverter. I don't know if all UPS employ this kind of system but there is definitely only one set of battery connect terminals?! There is a secondary output but can only charge a starter battery at 4A, it's an independent trickle charge output. If you wish to confirm this the manual is here: http://www.victronenergy.com/upload/documents/Manual%20-%20MultiPlus%203k%20230V%20Ve.Bus%20enabled%20-%20rev%2000%20-%20EN%20NL.pdf
    I've now found out I could use our existing GC solar to power the UPS by adding a solar switch which would utilise the grid disconnect in case of power outage and switch the output of the PV array to the UPS.
    How brilliant is that!!?
    I just hope I can use it; our GC is 12 x 190w & 2.2kW inverter. The Solar Switch manual says: in case of a MultiPlus 24/3000/70 (like the one I have), the maximum charging power is 24V x 70A = 1680W. If the grid inverter “tries” to feed more than 1680W back into the MultiPlus, not all power can be absorbed and the system will shut down.
    Am I correct in assuming the 2.2kW GC inverter would hardly ever produce over 1680W? The most ever showing on the GC inverter panel was 1600W from memory in summer. We have no North facing roof space here so PV array is installed facing East losing some potential.
    The AC OUT will invariably be lower, as the AC IN has to include allotment for the inverter's charge function. 3000 Watts on 240 Volts is 12.5 Amps. Using the NEC mark up rules that's a 20 Amp breaker. The 16 Amp input, by the same rules, would want a 30 Amp breaker. However, I strongly suggest you check your local codes on this. The Code of Good Practice we use here in the frozen wastelands would have 20 Amp breaker on the input and 15 on the output. If anyone complains, we have a complaint department: see Mr. G. Bear.

    The 30A breaker before the AC input is required here by reg's so that's a definite tick on the list of things to get.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    westbranch wrote: »
    Yes, we had 'Roo at a BarBee when we visited Oz a while back, when down for a wedding, not connected with the 'Roo feed.. it's much like wild game meat here (which can be a bit of a delicacy at times as less plentiful than 'Roo).

    cheers

    Hey westbranch, I make a mean venison goulash. The authentic recipe does warn against biting down too hard as there may be shotgun pellets present.:grr
    We can buy it here from farms down south but pellet-free. :D
    Back to kangaroos, did you travel at all within Australia? When we came here we drove across the bottom part from Sydney to Perth; three months towing a caravan. The number of roo carcasses at the side of the road was a sad reality, especially crossing the Nullarbor plains. Lucky we haven't hit one yet in 8 years, even though we do a fair bit of travelling/caravaning. the bull-bars on 4WD are merely going to stop a large roo from reaching the windscreen but would still do a fair amount of damage, one hopes it wouldn't damage the engine or drive train when out in the middle of nowhere. Road train trucks have massive bull-bars and most truckies barely feel hitting something while watching TV or reading their newspapers (or porn) at the same time as driving. :D
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Okay if there's no separate charge controller for the solar there's no place to put any additional fusing. All you have is the box and the batteries and the circuit protection between the two has to be capable of handling the maximum current that will flow.

    The other function is called "AC coupling". Good to know it can make use of that, as it is handy in an outage. You pay all that money for a GT system and it becomes useless when the power goes down! You have no idea how many inquiries we get about that little problem.

    The average output of your 2.2 kW GT can easily exceed 1680 Watts (2280 Watt array @ 77%). But the AC coupling is on the load side, so there should be loads drawing off it keeping the actual power going to the inverter/UPS below the maximum. A mere 100 Watts ought to do it most of the time. And if it does shut down, the GT will too (no sync). Then does the UPS automatically restart? If it does, so would the GT when it detects AC source of the right V & F.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Okay if there's no separate charge controller for the solar there's no place to put any additional fusing. All you have is the box and the batteries and the circuit protection between the two has to be capable of handling the maximum current that will flow.

    Sorry about the misunderstanding Marc, I am planning on installing an off-grid solar with separate solar charge controlller but thought I'd get the UPS and battery bank finished first to see if we can benefit from charging batt's overnight and use the stored power during the day; different $/unit if you remember.
    The other function is called "AC coupling". Good to know it can make use of that, as it is handy in an outage. You pay all that money for a GT system and it becomes useless when the power goes down! You have no idea how many inquiries we get about that little problem.

    It sounds like a great option, it would be great to be able to use the GC for extended outages. There is now an increasing number of people, including myself, aware of the possible grid meltdown predicted (kind of) end of 2012 however, there is not much info available on how to protect equipment from EMP's other than grounded steel boxes with insulation inside, foil wrappimg, etc.. What is your view on this?
    The average output of your 2.2 kW GT can easily exceed 1680 Watts (2280 Watt array @ 77%).

    The 2.2kW GT output does exceed 1680w according to my wife, she has seen the PV produce high 1900w at times which sounds more along the lines of the predicted performance prior to installation. The installer said we'd lose on average 10% due to East facing + some more due to inverter efficiency/inefficiency.

    But the AC coupling is on the load side, so there should be loads drawing off it keeping the actual power going to the inverter/UPS below the maximum. A mere 100 Watts ought to do it most of the time. And if it does shut down, the GT will too (no sync). Then does the UPS automatically restart? If it does, so would the GT when it detects AC source of the right V & F.

    I hope the unit restarts itself. It does reconnect loads loads if disconnected due to battery discharge, see quote 'C' on page 5 of the manual; Batteries discharged: All loads are disconnected. Solar energy is used to recharge the battery. The loads will be reconnected after (partial) recharge of the batteries.
    There is no reference as to the system auto-restarting once the GT output goes below the max 1680w.
    I thought the 1680w max refers to the PV array output? Would I be able to install a dummy load, water heater or something to use excess PV output, before it reaches the max 1680W in order to keep the solar switch from shutting down the system?
    The solar switch brochure is here: http://www.victronenergy.com/upload/documents/Brochure%20-%20Solarswitch%20-%20SAL064122020%20-%2002%20-%201103%20-%20EN_web.pdf
    I can't find an installation manual for the solar switch to give further insight into the workings.
    Initially, I was going to add an off-grid solar array & standalone charge controller. Would this be the better option or should I look into the solar switch to connect the existing GC. The latter would cost less and I could relocate the battery bank & UPS to be next to the existing GC unit which is located at the shed, next to the properties mains grid panel around 15 meters from the house (connected to the grid at property boundary 70 meters away).
    If off-grid is preferred I would go ahead and locate the UPS & batt bank inside the house to be directly below the proposed off-grid array.
    We have grid supply at boundary, 70 meters underground connection to main panel at shed (3 phase also), GC solar inverter next to panel, underground conduit installed to connect proposed sub-panel in house (probably single phase 240v as ther is no need for 3 phase there, any 3 phase loads will be used at shed).
    Shed is not your usual small garden shed, it is 16 meters x 7 meters and currently one half used as home; insulated & plaster-boarded kitchen, living area, bedroom & bathroom and the other half caravan/RV & storage.
    Sometimes, if you mention you live in a shed people picture a quaint little 6 x 6ft shed and find it impossible to grasp the idea of living in a shed but this is what most people do here while building to eliminate rent and travelling expenses.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    I build sheds sometimes. They tend to be not your average garden-variety, if you know what I mean. ;)

    If you've already got the grid-tie system and it's not too difficult to hook up to the new unit, you might as well try it and see how it works. As far as I know, the Watt limit on that is the amount of power fed to the UPS not the total generated by the panels (as that could be much different if loads are on as mentioned before).

    On the whole it sounds like a pretty good set up. Even so, you should expect to have to "tweak" things a bit once it is installed. Every install is slightly different, and not the least of that is in how you use it. Like having the array pointed somewhat to East so it gets full sun earlier in the day before the heat comes up. Oh I forgot: you're in Australia; the heat is always up! :p
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    I build sheds sometimes. They tend to be not your average garden-variety, if you know what I mean. ;)

    If you've already got the grid-tie system and it's not too difficult to hook up to the new unit, you might as well try it and see how it works. As far as I know, the Watt limit on that is the amount of power fed to the UPS not the total generated by the panels (as that could be much different if loads are on as mentioned before).

    On the whole it sounds like a pretty good set up. Even so, you should expect to have to "tweak" things a bit once it is installed. Every install is slightly different, and not the least of that is in how you use it. Like having the array pointed somewhat to East so it gets full sun earlier in the day before the heat comes up.

    It makes more sense to keep the setup close to the main power panel and run the 240v output from the inverter along the same path as the mains for the house. I still have some roof space on the shed to add an off-grid next to the GC panels. This will also free up the part of the walk-in-wardrobe I allocated for the 'power room'. The solar switch isn't cheap at $800 but still less than an off-grid array & solar charge controller. I'm looking forward to the 'tweaking' part.:D
    I'll find out about the watt limit beforehand.
    Oh I forgot: you're in Australia; the heat is always up! :p

    Well, we do have some cold weather right now with winter starting in a few days. Temperatures dropped down to about 3 degrees celsius at night and reach 20-25 degrees during the day but then for you this would probably seem like a lovely summers day. :p
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Sascha wrote: »
    Well, we do have some cold weather right now with winter starting in a few days. Temperatures dropped down to about 3 degrees celsius at night and reach 20-25 degrees during the day but then for you this would probably seem like a lovely summers day. :p

    Minus 3 eh? Yeah we sometimes warm up that much. -40 to +40; that's us. Sometimes in the same day.
    But more sunshine here than down on the coast! :D
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    The inverter's fuse rating is 300 Amps. If you put individual battery string fuses in for two strings they would be at least 150 Amps and not more than 300 Amps. Any disconnect needs to be rated for over 300 Amps (like the 350 Amp Blue Sea battery switch).

    The AC OUT will invariably be lower, as the AC IN has to include allotment for the inverter's charge function. 3000 Watts on 240 Volts is 12.5 Amps. Using the NEC mark up rules that's a 20 Amp breaker. The 16 Amp input, by the same rules, would want a 30 Amp breaker. However, I strongly suggest you check your local codes on this.

    Hi Marc,
    I have now found a more detailed installation manual;
    Models with 16A transfer capacity (eg MultiPlus 12/3000/120-16 230V)
    • AC-in
    The AC input cable can be connected to the terminal block “AC–in”.
    From left to right: “PE” (earth), “N” (neutral) and “L” (phase).
    The AC input must be protected by a fuse or magnetic circuit breaker rated at 16A or less, and cable cross-section must be sized accordingly. If the input AC supply is rated at a lower value, the fuse or magnetic circuit breaker should be down sized accordingly.
    • AC-out-1
    The AC output cable can be connected directly to the terminal block "AC-out-1".
    From left to right: “PE” (earth), “N” (neutral) and “L” (phase).
    With its PowerAssist feature the Multi can add up to 3kVA (that is 3000 / 230 = 13A) to the output during periods of peak power requirement. Together with a maximum input current of 16A this means that the output can supply up to 16 + 13 = 29A.
    An earth leakage circuit breaker and a fuse or circuit breaker rated to support the expected load must be included in series with the output, and cable cross-section must be sized accordingly. The maximum rating of the fuse or circuit breaker
    is 32A.

    The above is for a 12v model, mine being 24v would this make any difference to the fuses amp ratings? If not, I'll go 16A on the input and 30A on the output, correct?:confused:
    I can use 10mm2 twin & earth cable, fire rated on both ends unless you recommend otherwise. I have been given about 70 meters of this cable so it's free. The thicker cable shouldn't have any negative effect on this other than it being more cumbersome to work with, am I right?:confused:
    Is the 'earth leakage circuit breaker' mentioned to be installed in series with the output a separate unit or would this be part of a standard domestic 240v/30A circuit braker?:confused:
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Lots of good stuff in instruction manuals, eh? One of the best things anyone can do before buying a piece of equipment like this is to see if the manual is available on-line and read through it. You may find features you like, or dislike, and will definitely get a better idea of what you're in for if you buy it.

    The battery Voltage should have no bearing on the AC in or out if the units have the same AC ratings. It just means the 24 Volt version draws half as much DC current to supply the power as the 12 Volt version would.

    As a rule, thicker cable handles more Amps with less V-drop so the only disadvantage is the price (in this case free) and the difficulty in connecting it up.

    "Earth leakage circuit breaker", I'm guessing, is what we call a ground-fault breaker. You should be able to buy a breaker that fits this function and goes in a standard breaker box. It would be in place of, not addition to, a standard breaker. I doubt it is actually necessary, and may not be desirable when feeding multiple circuits. I prefer GFCI at the point of use for this, with the except of things like washing machines which can burst hoses and spray water until it saturates the wall and the (still like) wiring within. (Yes, I know.) GFCI breakers are good for that, or jet tubs/hot tubs or well pumps.

    Their terminology of "neutral" and "phase" is a bit odd for a 240 VAC system. Usually it's L1 and L2, at least over here. But we do lots of odd things like splitting 240 into two 120 lines against a center-balanced and grounded neutral.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Lots of good stuff in instruction manuals, eh? One of the best things anyone can do before buying a piece of equipment like this is to see if the manual is available on-line and read through it. You may find features you like, or dislike, and will definitely get a better idea of what you're in for if you buy it.

    The battery Voltage should have no bearing on the AC in or out if the units have the same AC ratings. It just means the 24 Volt version draws half as much DC current to supply the power as the 12 Volt version would.

    As a rule, thicker cable handles more Amps with less V-drop so the only disadvantage is the price (in this case free) and the difficulty in connecting it up.

    "Earth leakage circuit breaker", I'm guessing, is what we call a ground-fault breaker. You should be able to buy a breaker that fits this function and goes in a standard breaker box. It would be in place of, not addition to, a standard breaker. I doubt it is actually necessary, and may not be desirable when feeding multiple circuits. I prefer GFCI at the point of use for this, with the except of things like washing machines which can burst hoses and spray water until it saturates the wall and the (still like) wiring within. (Yes, I know.) GFCI breakers are good for that, or jet tubs/hot tubs or well pumps.

    Their terminology of "neutral" and "phase" is a bit odd for a 240 VAC system. Usually it's L1 and L2, at least over here. But we do lots of odd things like splitting 240 into two 120 lines against a center-balanced and grounded neutral.

    I always read manuals (unlike my wife who uses things first by guessing and then wonders why..:grr.) but understanding them is sometimes an issue..., that's why I'm picking your brains.8)
    I don't know why they call it 'phase', it's just a 'live' wire. Maybe a poor translation from Dutch? Phase is a different thing here also; we have 3 phase connected for industrial equipment and/or tankless water heaters, etc. for better efficiency, standard domestic power is single phase.
    I assume the 'Earth leakage circuit breaker' or 'ground-fault breaker' is what we use here in wet areas or outdoor sockets. RCBO which we have discussed earlier on in one of the threads within this post (http://en.wikipedia.org/wiki/Residual-current_device). I should perhaps get one of those to be on the safe side instead of a standard RCD-RCCB. The AC OUT will after all run underground from the shed to the house. Do you suggest I fit one in the sub-panel in the house AS WELL or INSTEAD of one at the AC OUT from the UPS?:confused:
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Sascha wrote: »
    I always read manuals (unlike my wife who uses things first by guessing and then wonders why..:grr.) but understanding them is sometimes an issue..., that's why I'm picking your brains.8)

    This explains why I have no brains left; people keep picking them apart.
    I don't know why they call it 'phase', it's just a 'live' wire. Maybe a poor translation from Dutch? Phase is a different thing here also; we have 3 phase connected for industrial equipment and/or tankless water heaters, etc. for better efficiency, standard domestic power is single phase.

    I rather thought you had single phase power with two "live" (or "hot") wires rather than the touch-friendly grounded neutral. Do they ground one side there? I shouldn't think that would be a good idea.
    I assume the 'Earth leakage circuit breaker' or 'ground-fault breaker' is what we use here in wet areas or outdoor sockets. RCBO which we have discussed earlier on in one of the threads within this post (http://en.wikipedia.org/wiki/Residual-current_device). I should perhaps get one of those to be on the safe side instead of a standard RCD-RCCB. The AC OUT will after all run underground from the shed to the house. Do you suggest I fit one in the sub-panel in the house AS WELL or INSTEAD of one at the AC OUT from the UPS?:confused:

    Pretty sure that's what it is: ground-fault protection. When it comes to that, one only on a line; never in series. Put it wherever the breaker needs to be, which is usually as close to the source (in this case the UPS) as possible.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    I rather thought you had single phase power with two "live" (or "hot") wires rather than the touch-friendly grounded neutral. Do they ground one side there? I shouldn't think that would be a good idea.
    Pretty sure that's what it is: ground-fault protection. When it comes to that, one only on a line; never in series. Put it wherever the breaker needs to be, which is usually as close to the source (in this case the UPS) as possible.

    Thanks Marc, I'll install one 'RCBO', 'GFCI' or 'the-thingy-that-trips-the-circuit-when-ground-is-detected-in-live-circuit' right after the UPS.
    We have domestic single phase 240v; one live (red), one neutral (black) & one ground (green or yellow/green), I think. I'm not so sure about the lot having read wikipedia; In most countries, household power is single-phase electric power, with two or three wired contacts at each outlet.
    The live wire (also known as phase, hot or active contact), carries alternating current between the power grid and the household.
    The neutral wire completes the electrical circuit by also carrying alternating current between the power grid and the household. The neutral is staked into the ground as often as possible, and therefore has the same electrical potential as the earth. This prevents the power circuits from rising beyond earth, such as when they are struck by lightning or become otherwise charged.
    The earth wire or ground connects cases of equipment to earth ground as a protection against faults (Electric Shock).
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Sascha wrote: »
    The neutral is staked into the ground as often as possible

    Does John Wiles know about this?! Sure seems contrary to the single ground point rule. :roll:
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Does John Wiles know about this?! Sure seems contrary to the single ground point rule. :roll:

    Who he?
    I don't know if we have this arrangement in Oz but wiki says most countries do. It just seems odd to me (limited knowledge of ELEC) to ground something that caries current? I thought red & black were alternating currents like current travelling in both directions?:confused:
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Sascha wrote: »
    Who he?
    I don't know if we have this arrangement in Oz but wiki says most countries do. It just seems odd to me (limited knowledge of ELEC) to ground something that caries current? I thought red & black were alternating currents like current travelling in both directions?:confused:

    Mr. Wiles is the head honcho for the National Electrical Code in the U.S. They come up with all sorts of interesting rules to inflict upon North America.

    Normal power here has the neutral grounded, because it is split phase 120. The neutral line is quite safe to touch when not in an active circuit. Otherwise it carries the return current and is not safe to touch. Rather different from the 240 VAC we have which has no neutral line. With the 120, only the "hot" line needs circuit protection. With 240 both lines are hot and need to be turned off in the event of a problem such as over-current or ground-fault.

    Yes, it's complicated. The Code Book looks like an annotated version of something written by Tolstoy.
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Hi Marc,
    I went out and bought this Blue Sea switch (following your recommendation, of course;)) http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=270956926990&ssPageName=ADME:X:eRTM:AU:1123 and I was thinking..., do I still need a bus to parallel join the two strings or can I just connect each, already fused string (200A fuse each) directly to the two terminals of the switch? When the switch is in the '1 + 2' position the two strings will be joined in the same way as bus and the switch then also gives me the option of isolating one string for whatever purpose. Any con's with this proposal, the con's being the saving on the cost of a bus bar and this switch being the same price as a 9003E, on/off swich. The only con I see is twice the elegth of cable from strings' positive AND negative, positive to switch and negative to bus bar (both, + & - the same length parallel connecting wires to keep them equal).
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Nothing wrong with connecting the two battery strings directly to the switch. In fact it has an added advantage of eliminating a couple of connections. The cable length may be an issue; how long are they going to be?

    Incidentally, this is one area where you can play parallel wiring to your advantage: by having one strand of, say, 0 AWG coming from each battery string and joining together nearer the inverter you reduce the length of the wire run that has to take the full current. That will lower the over-ll resistance and improve the Ampacity. But you do have to make sure the wire runs are equal, otherwise it will work against you (by creating a greater difference in resistance between the parallel runs and thus unbalancing the strings).

    It's a bit like juggling, isn't it?
  • SaschaSascha Solar Expert Posts: 121 ✭✭✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
    Nothing wrong with connecting the two battery strings directly to the switch. In fact it has an added advantage of eliminating a couple of connections. The cable length may be an issue; how long are they going to be?

    Incidentally, this is one area where you can play parallel wiring to your advantage: by having one strand of, say, 0 AWG coming from each battery string and joining together nearer the inverter you reduce the length of the wire run that has to take the full current. That will lower the over-ll resistance and improve the Ampacity. But you do have to make sure the wire runs are equal, otherwise it will work against you (by creating a greater difference in resistance between the parallel runs and thus unbalancing the strings).

    It's a bit like juggling, isn't it?

    G'day Marc, well..., 5:30 am here. Well, started typing at 5 am and finished now:D
    The positive strands from each battery will be around 3ft, including the fuse holders located just before the switch, the negative strands will be the same legth with a bus bar next to the switch and from positive switch & negative bus less than 1ft to the UPS terminals. I'm allowing 1ft for the latter to give me enough room to connect to the terminals but could even be less as I want to locate the switch right underneath the UPS unit, just give it some clearance from the fan located at the base of the UPS. I want to keep the fuse holders outside the battery box to avoid unnecessary sparks in there. Does this sound good to go?
    Should the fuses be closer to the batteries or can they be located just before the switch & bus bar?
    I was going to run the 0 gauge wiring behind a 6mm cement sheet (like vilaboard) but think it should perhaps be accessible and run on the surface. There shouldn't be any reg's breaches with this considering it is LV wiring, even though it only has a flexi-plastic sheath and the whole setup will be housed in a small steel lean-to shed with the battery bank housed in the lower part including tilted lid to channel any gas through a vent at the higher end. The mains wiring to & from the UPS will be behind a removable cement sheet section. I would like to insulate the cavity with EarthWool insulation which is non-combustible but am concerned about the possible heat the cables would retain due to this insulation. Should I be concerned about this heat and use conduit?
    The 0 AWG wire sent to me has Audio Cable 0 gauge printed on the sheath; fine, multistranded copper in red sheath and seems thicker than it should be, I guees the strands loosen up when the sheath is removed. I was struggling to insert all strands into the 0 AWG teminal connectors. I ended up force-widening the cable entry so the first 2mm or so is funnelled so I could insert 100% strands all the way in and then crimped solid. There is no movement inside the terminal connectors whatsoever so I assume the connections are solid. I used 12T hydraulic crimping pliers to do this.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    There should be no issues with "sparks" from fuse holders, no matter where they are located. They're not supposed to do that. Blue Sea makes fuse blocks that go right on the battery posts; no problem. Generally fuses/breakers are locate as close to the power source as possible.

    You're over-thinking the heat issue. Cement board and rock wool aren't necessary unless code says so, even then it would probably be to put it between the wires and combustible materials. Filling over wires with rock wool is not a good idea. You do want wire accessible. Conduit is another matter; needs to be used where code requires it, but constricts heat radiation and so reduces Ampacity. Usually it's only need in "accessible areas" like living space or where people would frequent. This is one of those 'round in circles code issues that can create lively arguments. Up here you are not allowed to cover over wiring within a foot of things like breaker boxes, sub panels, or what is loosely termed "major component installations", and then they tell you you need conduit for it because it can't be accessible while at the same time it has to be accessible. If that makes sense to you, maybe you can explain it to me. One particularly dim AHJ can really mess things up. :roll:

    Fine strand wire can be a real problem to get a solid lug connection on. It likes to slip and slide and getting a tight crimp can be tricky. Sounds like you've managed to do it. Never heard of 0 AWG audio cable; it's usually welding cable up here.
  • BB.BB. Super Moderators, Administrators Posts: 29,348 admin
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    I would always assume that there is a chance of sparks with fuses and breakers unless they are rated for use in explosive environments.

    Mounting a fuse block on battery terminals in a well vented battery box/room is probably not a huge issue... However, I do agree with doing what you can to reduce the chances of ignition of hydrogen fumes. Keeping fuses away from the battery caps will probably be a help (reduce the chances of burning derbies falling onto battery caps and igniting internal hydrogen gas a cell).

    If it was a choice between No Fuse vs Fuse in battery box, I probably would choose the fuse in the battery box.

    -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: »
    If it was a choice between No Fuse vs Fuse in battery box, I probably would choose the fuse in the battery box.

    -Bill

    Hi Bill, in other words are you suggesting the fuse blocks should be closest to the batteries rather than just before the switch? There will definitely be fuses, just need to know best placement. I was going to mount the fuseblocks just above the battery box and just below the switch which will have the UPS above. :confused:
    You probably meant fuseblock within battery box is better than no fuse at all.
  • BB.BB. Super Moderators, Administrators Posts: 29,348 admin
    Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

    Yes, fuse block near (or in) the battery box is better than no fuses at all (it is scary to watch wiring turn red hot and have nothing handy to stop the current flow).

    Fuses are to protect wiring against high current power sources (typically the battery bank in an off grid system). I believe that many specifications for boats/etc. say to put the fuses/breakers within ~18 inches (~0.5 meters) of the power source...

    In the end, the issue is to protect as much wiring as you can with the fuse/breaker. if the "unprotected" wiring is well protected and not going to get pinched by a metal door, caught on sharp edges, etc.--Then mounting the fuse/breaker panel farther than 18 inches away is going to be fine.

    In many ways, you are protecting against the unknown (say a small animal gets in and chews the insulation off the wiring bundle tied next to a metal stanchion), you want the fuse to stop the current near the battery bank, not after the failed insulation (as an example). Another person here had a long AC wiring run from his genset that failed inside the conduit (never heard how it failed)--Insulation could have been torn during installation... Who knows.

    -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
    There should be no issues with "sparks" from fuse holders, no matter where they are located. They're not supposed to do that. Blue Sea makes fuse blocks that go right on the battery posts; no problem. Generally fuses/breakers are locate as close to the power source as possible.

    You're over-thinking the heat issue. Cement board and rock wool aren't necessary unless code says so, even then it would probably be to put it between the wires and combustible materials. Filling over wires with rock wool is not a good idea. You do want wire accessible. Conduit is another matter; needs to be used where code requires it, but constricts heat radiation and so reduces Ampacity. Usually it's only need in "accessible areas" like living space or where people would frequent. This is one of those 'round in circles code issues that can create lively arguments. Up here you are not allowed to cover over wiring within a foot of things like breaker boxes, sub panels, or what is loosely termed "major component installations", and then they tell you you need conduit for it because it can't be accessible while at the same time it has to be accessible. If that makes sense to you, maybe you can explain it to me. One particularly dim AHJ can really mess things up. :roll:

    Fine strand wire can be a real problem to get a solid lug connection on. It likes to slip and slide and getting a tight crimp can be tricky. Sounds like you've managed to do it. Never heard of 0 AWG audio cable; it's usually welding cable up here.

    Sorry Marc, It is 0-gauge-car-audio-POWER-cable. I guess the difference between this and power-cable is the fancy transparent red sheath.
    I'm insulating the lean-to shed/power enclosure to reduce outside temperatures and also to reduce the risk of EMP's if doomsday does come...:D It will keep components isolated from the metal shed enclosure which will be independently grounded. Also, because I have access to free insulation; I sell the stuff!
    I'll run all wiring on the surface, the shed will be lockable and I may even display appropriate warning signs on the door to keep the local shire inspector happy in case he pays us a visit which is highly unlikely.;) The 240v 10mm cable is shielded anyway, designed for underground wiring.
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