Greetings,
Thank you all for contributing and making this forum a valuable resource in the renewable energy world.
I am upgrading an off-grid system (48V) in Haiti, and I would sincerely appreciate some help with a few technical questions I haven’t been able to find definite answers for.
Here is a quick system summary:
• Array: (6) 315 Watt PV = 1890 Watts â€" Two strings of 3 (3S2P)
o VMP 37V â€" VOC 45.6V â€" ISC 8.93A â€" IMP 8.52A â€" Maximum Series Rated Fuse 15A
o I have attached the Classic sizing tool result for my panel configuration.
• DC Disconnect /Load Enclosure: MIDNITE SOLAR MNDC250 MINI 250 AMP DC DISCONNECT
• Surge Protector : MNSPD-115 & MNSPD-300
• Charge Controller: Midnite Solar Classic 150
• Battery : (4) Trojan SPRE 12 225 â€" 48 V Charging Parameters @ 77°F/25°C â€" Absorption 58.0V â€" Float 54.0V â€" EQ 64.8V
• Inverter: COTEK SD2500-148 2500 Watt 48 Volt Pure Sine Wave Hardwire Inverter
• PV wire 8 awg = Distance from Array to DC enclosure 33 ft
Questions:
Combiner: Midnite Solar MNPV3
• My understanding is that 2 parallel strings may not need fusing, so where would the positive cables from the array get connected inside the Combiner box? Would it hurt to connect those strings to (2) MNEDC15 MNPV15 breakers?
DC Disconnect Enclosure
• I have the MNDC250 Mini-DC enclosure. Is the MNEDC250 inverter breaker suitable for the 2500 W 48V inverter, or should a lower amperage breaker be used such as MNEDC175 or MNEDC125?
• I have noticed the MNEDC125 breaker only comes as the RT model.
• Most importantly, how does one determine which inverter breaker to use?
Classic Controller Cabling and Fusing
• 4 Awg THHN cables, rated for 90°C for will be used to wire the Classic 150. What size breakers should be used for PV input and PV output? I know this question keeps coming up in the forum, but yet I am still confused. I understand the primary goal of the
breaker is to protect the wire (THHN rated for ) therefore can a 100A Midnite breaker be used for both?
• Can I use panel breakers instead of din rail breakers â€" removing the din rail may give a bit more room inside the enclosure, not to mention the panel breakers are cheaper.
• What are other differences between the two types (din rail and panel) besides the way they are mounted, and the way the cables get connected to them?
• Are there more parameters that need to be taken into consideration besides the wire ampacity when choosing fuses/breakers?
Thank you for your help.
Harry
SunnyIAV,
Welcome to the forum,
Answers in order of asking:
Combiner....2 strings do not nessecarily need fusing because if one string shorts the other string will not have enough power to force power backwards through the failed string but when you have 3 or more the shorted string can be burned out and possibly set ablaze by the two good strings. If you have the MNPV-3 I would advise you to use it. It will be helpful for analysis of system failure by allowing you to test one string at a time.
The MNEDC breaker does not fit into the MNPV combiner, the correct breaker is the MNPV-15 wire the positive p.v. panel output to the + terminal of the PV breaker. These breakers are polarity sensitive.
DC disconnect......the 250 amp breaker is too big for that 2500 watt 48 volt inverter. The SD-2500-148 power draw is about 90 amps max so the MNDC-125 is the correct size there....don't worry about the remote trip, just don't use it......that is for birdhouse automatic shutdown.....usually not needed unless you get a picky inspector. You will need an adapter to fit that breaker in that box....it's a smaller frame size than the MNDC 175 &250 breakers...see it on MidNite page.....
Breaker size for continuous duty breakers is 1.25 times the maximum draw of the device to be protected. The Cotek SD-2500-148 uses 6 times 15 amp fuses internally so max amps is under 90 amps...breaker size = 90 X 1.25 = 112.5 amps...sized up to next standard size = 125 amps
Classic breakers...the classic @ 48 volt battery can output a max of about 86 amps so a 100 amp MNDC -100 breaker for the battery side, smaller for the p.v. Input
Please let me correct you on this....standard pricing the MNPV din rail breakers are less expensive than the MNDC breaker about 11.85 for MNPV and 14.80 for MNDC from NAWS.....prices not exact but close.......also the MNDC breaker is larger than the MNPV breaker.......differences...MNDC breakers are 100% duty cycle...MNPV breakers are not and must be up sized by 1.25 when used as continuous duty....(National Electric Code Definition of continuous duty...The device will be operated continuously more than 2.0 hours). This does apply to solar at least we hope for more than 2 hours of full sun.
I think that covers your questions.......stay tuned.....have fun with it and post any more questions here
David
Thank you Tecnodave for the welcoming mat and your quick response. That was were very helpful. As usual, answers bring more questions :)
Combiner....I meant to type the din rail breaker MNPV15 for the combiner not the MNEDC15 panel breaker. I have edited the original post. The main reason I mentioned using breakers for just 2 parallel strings, even if they are redundant is because I don't see a way to combine the two positive PV cables inside the MNPV3 unless I add an additional bus bar.
DC Disconnect...
I did notice the Cotek manual recommends an inline 90A fuse and 4 AWG battery-inverter cable. I did reach out to them to find out if I could use a bigger cable such as 2/0. Here is a quote of their answer:
" Using those size cables will not affect the operation, the larger cables will have less of a voltage drop which is a plus."
If I am using 2/0 inverter cable, can I still use the 125 Amp inverter breaker on the MNDC enclosure? I wouldn't mine adding an inline fuse near the battery as well. I guess that fuse will have too be sized according to the inverter cable size. I am not sure why I think I need inverter cables that are bigger than 4 AWG.
I have yet to find an adapter that will allow the MNEDC125 breaker to fit in the inverter breaker cutout of the MNDC enclosure box - The opening is 1.5' wide, a perfect fit for the MNEDC175 and 250, but not for the MNEDC125 which is 1" wide. The only adapter I could find is the MNBREAKER which allows a a 3/4" breaker to fit in 1" opening. Midnite sell the MNDC enclosure with the MNEDC 125, 175 and 250; I wonder how they fit the 125 breaker in that enclosure
You are right regarding the breakers price difference. In general the panel breakers tend to be a bit more expensive than their din rail counterparts except for the 80 and 100 Amps breakers; the din rail units are 150% more that the panel breakers.
Classic breakers ... I am still hung on the idea that breakers are primarily there to protect the wire. Using 4 AWG cable to wire the Classic was my reasoning to put a 100 Amp on the battery side of the Classic.
I did notice you agree with the same size breaker, but for a different reason, and I quote " The classic @ 48 volt battery can output a max of about 86 amps so a 100 amp MNDC -100 breaker for the battery side" You also mentioned I could use a smaller breaker for the PV output, what size would that be based on my system configuration? Do I still need to worry about wire ampacity?
Please bear with me, if I am asking a lot of questions, fusing a system properly has been my weaknesses for years, and I would be grateful if I could have a better understanding on the correct way to protect a system. I certainly don't want my system to keep tripping unnecessarily nor to be without proper protection because the fuses/breakers are too big.
So many of us think we can just Google it ;), it's not that easy, thus the respect and admiration I have for all the folks who post their questions and those who try their best to help.
Warm regards,
Harry
Regarding the MNPV3 combiner box - each positive PV string goes to the bottom of the breaker . The top of the breaker is a buss bar that connects all the breakers together and the main wire going back to the controller connects to that buss bar . The negatives from PV and from the controller get connected together on the common buss bar on bottom left .
See photo
http://www.midnitesolar.com/productPhoto.php?product_ID=78&productCatName=&productCat_ID=9&sortOrder=4&act=p
Larry
Regarding sizing the wire and breakers
You first determine the available amps. Then you determine what size wire you need to use for the voltage and amount of amps at the distance of wire you need. So you need to size for voltage drop and want to have it low enough . There are voltage drop calculators online to help with that or charts. If it isn't a far run what a lot of people might do is just size the PV input wire for the maximum the controller can handle and then fuse that size wire - which I think usually works to be 6 gauge for the Classic at 60 amps . That gives you option to add more PV in the future without having to redo the wiring too.
So yes - you fuse the size wire you are using . You can use larger wire for less voltage drop if needed and use a smaller breaker if you already had it . But you can't go the other way and use a larger breaker for smaller wire past it's rated amp capacity .
Hope that helps .
Larry
Quote from: ClassicCrazy on March 27, 2019, 09:02:23 PM
Regarding the MNPV3 combiner box - each positive PV string goes to the bottom of the breaker . The top of the breaker is a buss bar that connects all the breakers together and the main wire going back to the controller connects to that buss bar . The negatives from PV and from the controller get connected together on the common buss bar on bottom left .
See photo
http://www.midnitesolar.com/productPhoto.php?product_ID=78&productCatName=&productCat_ID=9&sortOrder=4&act=p
Larry
Thank you Larry - My main confusion has to do with the fact my array configuration has 2 parallel strings of 3. I understand why breakers are not generally needed for such configuration, however if the MNPV3 is used, I guess breakers will be needed because I don't see where the positive PV stings will go without them.
Harry
It is a lot easier to use a combiner box even if you don't need it. Like Dave said - by using the combiner box it makes it easy to just flip the breakers off for the PV at the combiner location - helps with any service or trouble shooting you may need to do .
Otherwise if you didn't have a combiner box and Dave said you didn't need one for two strings - you would just get two separate buss bars to connect the two PV stings together with the wire going to the controller . I have done something like that using copper compression nuts and taped them up for insulation but not the best practice . lf you have stuff around to do the job and a box to put the buss bars in then it is less expensive than getting a combiner box .
Oh I think you mean that you have the pv3 combiner box and wondering how to connect the positive wires and still use the box. You could just get a piece of buss bar and use that for positive and insulate it or make sure it doesn't touch the negative. Or one of those giant wire nuts that could fit all those wires but that is frowned on for low voltage DC I think because of potential oxidation of wires and possible poor connections in future maybe.
Larry
Harry,
Mind fog has arrived!
I led you wrong! The MNBREAKERADAPTER is to use MNDC breaker in a competors box which originally used 1" wide breakers.....fog clearing a bit...its for the Outback panels (maybe)or maybe it for Mstar panels, I forget , but do remember going there, been a while
I'm using a different DC box than you are. I have the MNDC15 a box for 15 MNDC breakers and one 125-250 amp breaker. The box has a knockout at the position of the large breaker. The opening will fit the MNDC125. Breakout the knockout out and fit the MNDC 175 or 250 into the larger opening.
I have not seen any of the other MN panels in an uninstalled condition but I assume that has the same knockout.
Breaker location and knockouts
___________________________
|__________________________| < breakout tab for 175-250
| |
O | | O < opening for 125
|__________________________|
|__________________________| < breakout tab for 175-250
Hey no drawing editor.....just keyboard characters...that's creative! Did not know I could that.
Anyway that is the idea. Hope you followed that, not sure that I did...lol
David
Edit. Posting inserted an extra line but get the idea.....maybe that is only on the MNDC15 panel, not sure
Edit II. I am wrong on the MNDC15....... I have a aluminum adapter under the breaker protector to mount the MNDC125 breaker into the opening for the MNDC175/250.....I have seen that breakout tab situation somewhere.....I do too much electrical work to remember every panel and system I work on. Double checking MidNite drawings of the MNDC15 box, it does not show any such breakout tabs. I do machining and welding so if something does not fit, I make it fit. I'm not too concerned with the code on my own installations for my own use. Paying customers get full code compliance. I do utility electric for a living.....keep solar as a hobby.
Harry,
On the wire sizing..... Inverter feed cables.....the NEC rates 4 ga. Wire at 100 amps, that is the minimum size for that wire BUT that is not for continuous duty! Normally for an inverter you do not want excessive voltage drop so we up size a bit. I'm using 2 gauge on my Cotek SK-1500 and I will upgrade that a bit one day. 2/0 is a bit overkill. won't hurt a thing. MagnaSine recommends 2X 2/0 for my MS4024AE Inverter.....4000 watt 24 volt with a 250 amp breaker at 5 feet maximum length wire......way more conservative than Cotek's recommendation. I'm using 2/0
David
Quote from: tecnodave on March 27, 2019, 10:26:30 PM
Harry,
On the wire sizing..... Inverter feed cables.....the NEC rates 4 ga. Wire at 100 amps, that is the minimum size for that wire BUT that is not for continuous duty! Normally for an inverter you do not want excessive voltage drop so we up size a bit. I'm using 2 gauge on my Cotek SK-1500 and I will upgrade that a bit one day. 2/0 is a bit overkill. won't hurt a thing. MagnaSine recommends 2X 2/0 for my MS4024AE Inverter.....4000 watt 24 volt with a 250 amp breaker at 5 feet maximum length wire......way more conservative than Cotek's recommendation. I'm using 2/0
David
Interesting - Outback recommended 4/0 wire for my 24v 3500 watt inverter . Maybe it has a higher surge capacity they are rating it for.
Larry
Larry,
MagnaSine and outback recommendations. are in close agreement
MagnaSine recommends 2 runs 2/0 266200 total circular mils. For 4000 watt. .015 w/c.mil
Outback recommends. 1 run 4/0. 211600. " " " For 3500 watt. .016 w/c.mil
Cotek. 1 run. 4 41,470. For 2000 watt. .048w/c.mil
So by that calculation watts per circular mil Cotek is running three times the watts of OB or MS per circular mil.
All the inverters are 24 volts
So by MS and OB standard that would be 133,100. AWG 2/0. for the Cotek
Yes, I think that the Cotek is on the light side recommending 4 ga at 90 amps
So @ Harry........2/0 is about right by American high quality inverter standards
david
Quote from: ClassicCrazy on March 27, 2019, 09:36:06 PM
It is a lot easier to use a combiner box even if you don't need it. Like Dave said - by using the combiner box it makes it easy to just flip the breakers off for the PV at the combiner location - helps with any service or trouble shooting you may need to do .
Otherwise if you didn't have a combiner box and Dave said you didn't need one for two strings - you would just get two separate buss bars to connect the two PV stings together with the wire going to the controller . I have done something like that using copper compression nuts and taped them up for insulation but not the best practice . lf you have stuff around to do the job and a box to put the buss bars in then it is less expensive than getting a combiner box .
Oh I think you mean that you have the pv3 combiner box and wondering how to connect the positive wires and still use the box. You could just get a piece of buss bar and use that for positive and insulate it or make sure it doesn't touch the negative. Or one of those giant wire nuts that could fit all those wires but that is frowned on for low voltage DC I think because of potential oxidation of wires and possible poor connections in future maybe.
Larry
Thank you for all the info - I guess I will just use two MNEPV15, the rated breaker for my panels, and connect each string to a breaker. Even though the breakers will be redundant, but I won't have to think outside the box and will have a clean install + the ability to shut down 1 string easily for troubleshooting as you and Dave suggested . I will also add an MNSPD115 surge protector to the mix.
Harry
Quote from: tecnodave on March 28, 2019, 02:09:19 AM
Larry,
MagnaSine and outback recommendations. are in close agreement
MagnaSine recommends 2 runs 2/0 266200 total circular mils. For 4000 watt. .015 w/c.mil
Outback recommends. 1 run 4/0. 211600. " " " For 3500 watt. .016 w/c.mil
Cotek. 1 run. 4 41,470. For 2000 watt. .048w/c.mil
So by that calculation watts per circular mil Cotek is running three times the watts of OB or MS per circular mil.
All the inverters are 24 volts
So by MS and OB standard that would be 133,100. AWG 2/0. for the Cotek
Yes, I think that the Cotek is on the light side recommending 4 ga at 90 amps
So @ Harry........2/0 is about right by American high quality inverter standards
david
Thank you Dave ... So if 2/0 is Ok to use from battery to inverter breaker located inside the MNDC enclosure do I still need to switch the MNEDC250 to MNEDC125?
Moreover, if I use 2/0 and add an extra 250 Amp inline fuse near the battery, which one would be recommended? I have been looking at class T fuses and MRBF that mounts neatly on the battery post, but it seems the MRBF fuses I have seen so far are not suited for 48V battery banks.
Harry
Hi Sunny,
The breaker is sized to protect the wiring. A 250 amp breaker is too large for 2/0.
You should check an online ampacity chart for your wire and choose a breaker that does not exceed that rating.
Doug
Quote from: Doug on March 28, 2019, 01:50:47 PM
Hi Sunny,
The breaker is sized to protect the wiring. A 250 amp breaker is too large for 2/0.
You should check an online ampacity chart for your wire and choose a breaker that does not exceed that rating.
Doug
Hi Doug - Thanks for the reply. I have looked at many charts, and it seems ampacity of THW wire copper conductor 167 deg F is 175 and THW-2 is 195. Do those numbers needs to be multiplied by 125% for continuous duty? I am aware that Midnite breakers can be used at 100% rated current when mounted in a MidNite enclosure.
Cobra X-Flex wire recommended by Midnite has even higher ampacity for 2/0 Wire - 336 Amps - Wonder if I understood that wrong
Link http://www.cobrawire.com/x-flex/x-flex.php
Thank you all, I am learning 1 post at a time.
I took a quick look at that chart and that rating is at 105°C.
The other numbers that you have look a lot closer to reasonable.
Hi SUnny..,
Doug is correct, here is one of the Footnotes in that Data SHeet that you Linked;
" ... **The 105°C cable ampacities are adapted from ICEA P-54-440/NEMA WC51-86(R1991). The ampacities are provided for informational purposes only. Acceptance of these values by any governing authority is the responsibility of the end user. Ampacities are based on a single conductor, in free air, at 30°C ambient air temperature. "
in the US, we normally use NEC Ampacities -- three current carrying conductors, in conduit/raceway, 40 C ambient.
Your standards are probably different.
EDIT: Should add, That Cobra cable appears to be Fine-Strand. This type cable may not be compatible with the connections on each end of this cable run.
Also, believe that all of the MN breakers are rated for 75 C maximum for cable connections, therefore 75 C Amapcity is the maximum useable rating -- use 75 C Ampacity Max.
There can be some ways to bend these ratings a bit. Again, it does depend upon any regulations that are applied there.
FWIW, Vic
Hi Vic... Thanks for your comments, I have read so many of your posts, and they have been very helpful.
If I am not mistaken the Cobra X-Flex I was referring to may be the same recommended by Midnite Solar for battery-inverter cable for the MNDC box because of its flexibility - bottom of page 3 of the MNDC manual - wire type section.
Link - http://www.midnitesolar.com/pdfs/mndc125_250_manual.pdf
I was also under the impression that Fine-Strand cable is widely used for battery cables'
I must admit that I was surprised the ampacity was so high for 2/0 and as you pointed out that is not an NEC chart.
By the way , when it comes to standard, I will follow the code for the US since there is no code I am aware of specific to Haiti.
That said, what would be the acceptable size for an inline fuse mounted close to the battery for 2/0 cable? I am sure the type of insulation may be a factor as well.
Harry
Harry,
I would use a 125 amp breaker for the Cotek inverter, that will protect the wire and the inverter.
There is no need for a larger breaker here. Personally I don't put a fuse right at the battery, I have very short cabling. But if you do make sure it is rated for the voltage used, some can arc over with too high a voltage.
On the NEC.....ampacities for each type of wire are different with the different types of insulation.
Battery cable and CobraXflex are not NEC types of cable and therefore are not listed in NEC charts.
The only type acceptable in the NEC is MTW (machine tool wire) this is not listed in any of my NEC charts. It is a fine strand type of wire and has 1061 strands verses 19 strand THHN. CobraXflex is even finer strand at 1056 strand. The outside diameter of the copper strands in fine strand is larger than 19 strand. Different terminals are used. They have a larger inside diameter than 19 strand terminals.
I have been buying my terminals at NAWS and Temcoindustrial.com Tower electric motor co. Near here in Freemont, CA. Their terminals are correct size for fine strand welding cable, CobraXflex., etc.
I use welding cable...1056 strand.......it's not code......it's rated for much tougher duty than NEC and I've never had an issue with it.
Temcoindustrial.com does have attractive pricing, great service and the best hydraulic crimper that I have seen in a while...they work well! I am going to post on these crimper so with some pic's so others can see these.....maybe in off topic....ill find a place for it.
These Crimpers can be seen on Amazon but I went to the source and bought direct from temco.
They are highly industrial (temco) but you can set up an account with Visa card of whatever? and still get good service onesey...twosey....big price break in quantity.
David
Hi Harry,
Had little time earlier. I should have mentioned that Fine strand cable needs lugs designed for the cable that is used, and crimped with proper tools and ides.
You are correct, that essentially all battery interconnects and inverter cables that we use for battery based systems ARE fine stranded.
Believe that the large MN MNEDC breakers have bolted connections, so it is just down to the cable lugs and the tooling to crimp them.
If the cable for the breaker is inside a MidNite e-panel, or similar, the free-air rating for a single cable would probably fly, although would use the 75 C Amapcity, due to the specs on the breaker.
Inverter cables are often not really In free-air, although on some older Xantrex systems 4/0 cable was supplied, and connected to a 250 A breaker. This appeared to be technically a bit undersized at 40 C in conduit with other current-carrying cables, but was CSA Listed, so there are fine details that can matter.
Am not a Code Expert. MidNite tech folks ARE experts, so would listen to them.
Good luck with your system, Harry. Vic
Quote from: tecnodave on March 28, 2019, 08:42:00 PM
Harry,
I would use a 125 amp breaker for the Cotek inverter, that will protect the wire and the inverter.
There is no need for a larger breaker here. Personally I don't put a fuse right at the battery, I have very short cabling. But if you do make sure it is rated for the voltage used, some can arc over with too high a voltage.
On the NEC.....ampacities for each type of wire are different with the different types of insulation.
Battery cable and CobraXflex are not NEC types of cable and therefore are not listed in NEC charts.
The only type acceptable in the NEC is MTW (machine tool wire) this is not listed in any of my NEC charts. It is a fine strand type of wire and has 1061 strands verses 19 strand THHN. CobraXflex is even finer strand at 1056 strand. The outside diameter of the copper strands in fine strand is larger than 19 strand. Different terminals are used. They have a larger inside diameter than 19 strand terminals.
I have been buying my terminals at NAWS and Temcoindustrial.com Tower electric motor co. Near here in Freemont, CA. Their terminals are correct size for fine strand welding cable, CobraXflex., etc.
I use welding cable...1056 strand.......it's not code......it's rated for much tougher duty than NEC and I've never had an issue with it.
Temcoindustrial.com does have attractive pricing, great service and the best hydraulic crimper that I have seen in a while...they work well! I am going to post on these crimper so with some pic's so others can see these.....maybe in off topic....ill find a place for it.
These Crimpers can be seen on Amazon but I went to the source and bought direct from temco.
They are highly industrial (temco) but you can set up an account with Visa card of whatever? and still get good service onesey...twosey....big price break in quantity.
David
Thank you Dave for all your input and education. My MNDC enclosure came with no breakout tab, on the side, just a 1" 1/2 opening suitable for the 175 or 250 breakers.I will need to get creative if I want to mount the 1' wide MNEDC125.
I had ordered some Cobra X-Flex 2/0 cable + 2/0 Compression lugs from the same location, I will have to contact them tomorrow for recommended fuse size. I wonder what Midnite recommends since they carry the Cobra X-Flex cable.
Link: http://www.midnitesolar.com/productPhoto.php?product_ID=448&productCatName=Battery%20Accessories&productCat_ID=39&sortOrder=7&act=pc
As a matter of fact the MIDNITE SOLAR E-PANEL PLUS, 250A FOR OUTBACK INVERTERS such as the
VFX3524(edited) come with the Cobra X Flex 2/0.
Thanks for the other thread regarding the the Temco crimping tool. I definitely will get one .
Harry
I always ordered the mini dc boxes that came with the breaker. If you ordered a bare box maybe it was the one sized for larger breakers - they do have a box for the 125 amp breaker. But I bet a piece of tin and some snips can make yourself and adapter or something to fill in the extra opening.
Larry
Larry,
I have looked for boxes for (breaker only) the MN125 DC and MN175/250DC found nothing, .......had an old 2 pole AC breaker box, sazsall's, drill, etc. made my own. Breaker handle on side. These breakers must be mounted vertically.
david
Quote from: tecnodave on March 30, 2019, 11:02:33 PM
Larry,
I have looked for boxes for (breaker only) the MN125 DC and MN175/250DC found nothing, .......had an old 2 pole AC breaker box, sazsall's, drill, etc. made my own. Breaker handle on side. These breakers must be mounted vertically.
david
This is what I am talking about .
https://www.solar-electric.com/mndc125.html
Larry
Larry,
I know about that one, I was looking for a box more like the MNDCQUAD but for the bigger frame size of the 125 breakers. Have a pile af AC boxes that I have pulled out of service, I find one with enough room and make my own. Same for my MagnaSine inverter. I did not want to buy an e-panel for a inverter which will be replaced by Rosie the inverter......I paid less for the MagnaSine than an equipped e-panel costs. I don't care about UL listings......building inspectors not allowed!
I ended making a box like the MNDC15 but for Carlingswich E frame breakers. It has 10 spaces and fits 2 ea MN250DC breakers and 2 ea. of the 156 amp 4 gang switches from the garage sale. They were 156 amp, 600 volt switches 4 poles in series. I made custom busses and paralled the switches for a 624 amp 150 volt battery switch. These are the main battery cutoff switches for inverters and DC loads on my 2 battery banks. All my controllers are breakered straight to the battery buss from the MNDC15 panel panel that I use as my main breaker box. Most DC load breakers are in the MNDC15 main breaker box. All loads go from the MNDC15 box to the main battery cutoff switches in the TDDC10 box.....the one I built. The controllers all feed from the input side of the load bank switches.........complicated but any controller can charge either bank but all loads are one one bank (either one) or both banks in parallel...Controllers have 2 DC breakers, one for each bank, two BTS's ,switchable, for monitoring temps....It always evolving, I just fiddle it and make improvements a bit at a time.
david
Quote from: ClassicCrazy on March 30, 2019, 11:06:48 PM
Quote from: tecnodave on March 30, 2019, 11:02:33 PM
Larry,
I have looked for boxes for (breaker only) the MN125 DC and MN175/250DC found nothing, .......had an old 2 pole AC breaker box, sazsall's, drill, etc. made my own. Breaker handle on side. These breakers must be mounted vertically.
david
Thank you fellows. I originally ordered the MNDC250, it came with the 250 amp breakers packed inside the box, and the breaker opening was already cut to fit that size. I can no longer return it to get one where the 125 breaker would fit since it's already over 45 days. The enclosure probably comes with a knockout plate that allows to fit two breaker sizes, and it get removed at some point to fit the appropriate breaker. This is a guess.
I am sure I will figure something out once I receive my MNEDC125 breaker.
Harry
This is what I am talking about .
https://www.solar-electric.com/mndc125.html
Larry
Harry
Quote from: SunnyIAV on March 27, 2019, 04:18:26 PM
I am upgrading an off-grid system (48V) in Haiti...
Where in Haiti is your system located? I've done a bit of solar work at a clinic in the Dumay area (south of Croix de Boquet).
Keith
Hi Keith,
I am at Ile-a-Vache, right in the middle of the Atlantic Ocean. I have read some of your posts here and at NAWS, they are very informative.
A big thank you for the work you are doing in Haiti. They definitely need it.
Harry
On Ile-a-Vache, you have to take everything with you the first time -- it's a long trip to get additional parts.
Do you use boats of planes to get there?
Keith
Hi Keith,
You are absolutely right right, you have to bring with you , if you need it. It’s a long trip 4 hour flight from NY, 5 hours by car to Les Cayes, depending on traffic than a 30 min boat ride .
This is the one of the reason I am trying to ask as many questions as possible, learn as much as I can in order to get all the right equipment down to the last washer. As you already know, missing one single piece of equipment can make the difference between proceeding with an installation and postponing until the next trip.
Thanks for forums like this one, and all the good hearted folks that graciously and generously share their knowledge.
Harry
Hardware - only Stainless Steel. boxes of 50, cheaper than looking for the washer that rolled off the roof. Real large hardware sizes, may come in 5 or 10 packs.
SS hardware has a habit of galling to itself when you torque it down. Using some anti-size lube will be good when you have to change something later and dont want to break it or your screwdriver
Quote from: mike90045 on April 06, 2019, 02:51:22 AM
Hardware - only Stainless Steel. boxes of 50, cheaper than looking for the washer that rolled off the roof. Real large hardware sizes, may come in 5 or 10 packs.
SS hardware has a habit of galling to itself when you torque it down. Using some anti-size lube will be good when you have to change something later and dont want to break it or your screwdriver
Thanks Mike, great advice. I have to use Stainless Steel over there at a minimum, salt spray gets into everything. After all, that is to be expected since my place is on a small island, and perched right above the ocean. Anti-seize lube and especially NO-OX-ID can be some your best friend in those conditions.
I read up on stainless steel galling recently . Yes put anti-seize on to prevent that . Also if no anti seize then you should go slow on tightening - using the cordless drill or fast ratcheting on nylock nuts will really get them locked up.
Larry