Correct usage of DIN rail terminal jumper bars? - Page 1
Forum section: electronics / beginners

author: Lomax
author_rank: Frequent Contributor
timestamp: October 19, 2020, 07:32:52 pm
content: I'm working on a project with 12V circuits, and am keen to use DIN rails for mounting and connections, but I don't understand how to correctly join/sum connections. If I have a block of DIN rail terminals providing ground for a bunch of external devices, it is tempting to use a jumper bar to join them together, so that I only need to make one connection on the "inside" - but the current rating of a standard 2.5mm2 DIN rail terminal is only 16A; what if the total current adds up to more than this? I could of course add more connections on the "inside" to increase the current capacity, but then what's the point of the jumper bars!? Or I could go up in size on the DIN terminals, to say 6mm2, but then each terminal would take up a wider space, despite only having a 2.5mm2 cable on the "outside".I guess what I'd like to see is DIN terminals with a larger connection on one side, and several smaller ones on the other? Another example, say I have a cabinet which distributes power to other places - I would like to feed the cabinet with a single thicker cable than those going out (via circuit breakers, of course). How do I distribute say a 25mm2 cable into 10x2.5mm2 cables? The more I look at it the more I think this is not the purpose of DIN rail terminals, but then what do you use? And if DIN rail terminals are not intended for distribution, what are they for!?

author: Kjelt
author_rank: Super Contributor
timestamp: October 19, 2020, 08:15:07 pm
content: If you want the terminal of a power supply to handle lets say 25A to be distributed to 10 times 2,5A users, you choose the apropriate dinrails for the max of the individual users in this case 2,5A. You then have the max diameter for that dinrail, you calculate max continuous nominal current for that diameter (not peak current) and then divide 25A through the Inom and that is the amount of wires you use to distribute the 25A to that block of terminals. Also make sure that the Inom of the jumper bars can handle it.The point is that instead of ten wires from the psu terminal to the individual users you have two or three wires to a terminal block and from there ten+ to the individual users.The main point of terminal blocks IMO is to neatly organize your wiring plan including labels (nrs) where you know what wire goes where and after three years you open the cabinet , grab the electrical schematic you printed and put in the inside of the door, and within 5 minutes you know what wire is what for and where it is located in the cabinet.

author: Lomax
author_rank: Frequent Contributor
timestamp: October 21, 2020, 09:52:17 am
content: Quote from: Kjelt on October 19, 2020, 08:15:07 pmOk, that's basically what I thought. But what do you do when your power source only has one (large) terminal? The only option I can see is to have a distribution block which takes a larger input. It would be neater if I could jumper a 25mm2 terminal to an arbitrarily wide block of 2.5mm2 terminals somehow, but the jumpers I've been looking at only fit one size of terminal, and do not handle enough current. It gets even worse on the input side, where the feed is often thicker than the internal connections (for obvious reasons), and needs to connect to pretty much every single device in the cabinet. I have seen these:But six outputs is nowhere near enough for my application - I need somewhere in the region of 20, which surely isn't extreme. It's also an awkward fit alongside standard DIN rail terminals - would you loop the wires back around into the terminals, put the distribution block on a separate lower rail, or connect the output wires directly to the distribution block (forgoing the labels)? What I'm I missing here? There must be an elegant solution to this common(!) scenario...Quote from: Kjelt on October 19, 2020, 08:15:07 pmTheWeidmueller WQV 2.5 4-way jumperhas an IMax of 32A. Plenty in a 240V application - not so impressive @ 12V. Perhaps DIN rails are not a good fit for 12V installations for this reason?Quote from: Kjelt on October 19, 2020, 08:15:07 pmAnd that's exactly why I'm keen to use themI just need to figure out how to deal with the power distribution!

author: elekorsi
author_rank: Regular Contributor
timestamp: October 21, 2020, 12:45:06 pm
content: Quote from: Lomax on October 19, 2020, 07:32:52 pmOne thing that must be considered is that where you have a reduction in cross section, fuses/circuit breakers must be installed to protect the cables, or lets say, the maximum current rating of the fuse depends on the smallest cross section in circuit.So if you have 2,5mm2 terminal blocks bridged together and rated for 16A, the input line to that should be fused with no more than 16A. This leads you to the answer that connecting anything more than 2,5mm2 on the input of that terminal block is usually useless (may be helpful to reduce the voltage drops on longer leads, but current should still be limited to those 16A).On control lines i usually use one of this instead of fuses or circuit breakers.https://mall.industry.siemens.com/mall/en/si/Catalog/Product/6EP1961-2BA11https://shop.murrelektronik.com/en/Electronics-in-the-Control-Cabinet/Intelligent-Power-Distribution/If i have let's say 24V/10A power supply in the cabinet, then if coupled directly without any fusing, the cross section of all control wires should be minimum 1,5mm2, which is of course ridiculous and impractical.The same goes for the second part of your question. If you will distribute 25mm2 into 10 separate 2,5mm2, then the 25mm2 cable will be protected by let's say 16A (may differ in + or -, depending on other conditions)...What you would really do, is install 10 circuit breakers with 16A rated current, with the 25mm2 cable connected to the busbar. For example, something like this:https://www.se.com/uk/en/product/A9XPH312/acti-9---comb-busbar---3l---18-mm-pitch---12-modules---100a/Then you are allowed to protect that 25mm2 cable with let's say 80A fuse (for B2 type installation, 3 current caring conductors, PVC insulation). Don't take that 80A for granted, it must be calculated on other factors...

author: Alti
author_rank: Frequent Contributor
timestamp: October 21, 2020, 01:22:39 pm
content: Quote from: Lomax on October 19, 2020, 07:32:52 pmYou need an appropriate din railterminal.This one is1x35mm2 to 24x10mm2kind of overkill for you, it can accept several 2.5mm2 wires in one hole.This one is1x35mm2 to 12x4mm2and more apropriate, just parallel two.There are separate brackets for those or you can buy themwith bracketsalready.This is a manufacturer's website and this is just an example.Mind EN version does not show prices (?).It is also quite convenient to make your own 35_to_2.5mm2 custom brass terminal by brazing 35mm2 and 2.5mm2. It is kind of soldering with the differece that the "solder" is much stronger than the brass itself.

author: Kjelt
author_rank: Super Contributor
timestamp: October 21, 2020, 02:27:51 pm
content: Quote from: Alti on October 21, 2020, 01:22:39 pmThose are PE earthing bars, are they allowed in your country to be used for voltages ?No insulation, nothing ?

author: Kjelt
author_rank: Super Contributor
timestamp: October 21, 2020, 02:35:16 pm
content: So Elekorsi is right that you should really take care of fusing or monitoring your currents.That said, a quick search I think I did find something you are looking for: Power feed-in terminal blocks.An example the Weidmuller AWPD 35 4X6/6X2.5 for instance takes in 35mm2and distributes to 4x6mm2and 6x2.5 mm2.There must be more solutions out there.https://catalog.weidmueller.com/procat/Product.jsp;jsessionid=D0B50572A194951347CD9077DD401241?productId=(%5bproduct16220220394315%5d)&groupId=(%22group11196612992149%22)&page=Product

author: Alti
author_rank: Frequent Contributor
timestamp: October 21, 2020, 04:01:51 pm
content: Quote from: Lomax on October 19, 2020, 07:32:52 pmQuote from: Kjelt on October 21, 2020, 02:27:51 pmThey are allowed to be used for PE earthing bars and do not need insulation in some circumstances. Notably, if the distribution board is made inI class. You just bolt that to the chasis.You can also use them for working voltages (but then you need a clip) and it must be IP20 IIRC so the user must not have access to this thing.Of course in OP's case my remarks are irrelevant as s/he wants that for 12V.

author: Jeroen3
author_rank: Super Contributor
timestamp: October 21, 2020, 05:53:21 pm
content: Wago, Phoenix Contact and Weidmuller have thousands of terminal blocks in all the sizes and configurations you want.I suggest you download their catalogs and start exploring their offerings.For 12V/24V they may even have (electronically) fused distribution blocks with indicators!

author: nightfire
author_rank: Frequent Contributor
timestamp: October 21, 2020, 09:16:43 pm
content: In my experience, at least here in germany, DIN rails are usually used for mounting and maybe ground/earthing them- also depending on the style of the distribution cabinet.Within 48V DC environments (for Telco use in a datacenter) I usually have seen busbars, where the wires would get a cable shoe and then get screwed onto that copper bars- on top of that usually sits a plastic cover to prevent accidental touching in operation.I could actually not find appropriate clamps in the online catalogue of some of the usual suspects of manufacturers- as 10 mm² are somewhat difficult to handle within a cabinet, you need some spacing to do that. So you could use some big clamps that can be connected within each other with some bridging connector and have about 10 of them available- makes 20 connectors...Like WAGO Art.-Nr. 2010-1307 - those can be bridged to each other. Other manufacturers should have some similar systems, also with bigger dimensions.

author: Renate
author_rank: Super Contributor
timestamp: October 22, 2020, 12:16:18 am
content: I know this isn't DIN, but you were speaking of 12 V, < 100 A distribution.https://www.bluesea.com/products/5034/ST_Blade_Fuse_Block_-_12_Circuits<- good photo, but not the model I meanhttps://www.bluesea.com/products/5029/ST_Blade_Fuse_Block_-_12_Circuits_with_Cover<- with coverI use this for 12 V distribution in my RV.For DIN breakers on a DIN rail has anybody mentioned these bus bars?https://my.rs-online.com/web/p/busbars/4896489/I could have used these when I put in my DIN rail for AC.Instead, I took a piece of #8 wire and soldered loops and tails of #12 to it at the DIN spacing.Then I wrapped it all up heavily in electrical tape.

author: wizard69
author_rank: Super Contributor
timestamp: October 22, 2020, 04:39:00 am
content: Any control panel wiring must be compliant with local codes. That is first and foremost.Quote from: Lomax on October 19, 2020, 07:32:52 pmThen you have a problem that must be resolved in some manner. Often the right approach is to create branch circuits that keep the current levels with in the wiring system capability. It isn't just the terminal blocks, but all wiring must be protected. You can't put 20 gage wire on a circuit capable of delivering 20 amps for example. You need too mind both the supply and return wires.In a case some time ago we had panels that had a very large umber of single phase AC loads. To keep everything reasonable wiring wise we had to fuse/breaker multiple 15 amp circuits. Each circuit was a paired with a designated neutral, for example numbered N1, N2 and so forth. This keep the neutrals associated with the circuit derived via the beakers. This avoids mix up in the field where everyone assumes that every white wire is the same. It was good practice becaue I had previous experience in another location where the current carrying capacity of the neutral wasn't minded and that resulted in melted down terminal blocks.QuoteJumper bars are not magic. They do the job of handling many devices off of a supply. You are still responsible for using them properly.Quote

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: October 22, 2020, 05:43:24 am
content: Two ways to solve this, Phoenix Contact makes terminals in different sizes, for various wire gauges and current ratings. They also make a series of "reducing bridges" which allow you to bridge between different sized terminal blocks.The other is to use dedicated potential distributor blocks, such asMersen's FSPDB3A, these are DIN rail mountable, have 16 outputs, can handle 70 mm2 input cable, and are rated for 310A. I'm using a couple of these to distribute power from a 6 kW, 28V power supply to twelve RF amplifiers.

author: Renate
author_rank: Super Contributor
timestamp: October 22, 2020, 12:13:11 pm
content: Quote from: radar_macgyver on October 22, 2020, 05:43:24 amMmm, I don't like this, the outputs can still do 310 A.I don't like connecting "hot" big wires to little wires under any circumstances.I want "hot" big wires to go to solid metal which connects in the shortest possible manner to circuit breakers or fuses.I'm surprised that there are no non-modular solutions for this on DIN rails.This is the closest that I've seen, but I'm not fond of PCB type things.Edit: Oops, forgot link:https://czh-labs.com/products/czh-labs-din-rail-mount-ac-dc-532v-10-position-power-distribution-fuse-module-board-p0445

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: October 22, 2020, 03:27:30 pm
content: Quote from: Renate on October 22, 2020, 12:13:11 pmOnly if you let them. The individual loads (amplifiers in my case) are fused, or have breakers, of appropriate rating; the full source current can't flow through the branch lines, unless the breaker fails (that's why you always use a backup fuse). If one follows this logic too rigidly, it's a case of "turtles all the way down", where would you ever have a smaller diameter wire in your design?To the OP, there's also the Phoenix Contact PTFIX series potential distribution blocks, which have a modular design and are meant for one-to-many distribution applications in wiring cabinets, for example,3273460.

author: Renate
author_rank: Super Contributor
timestamp: October 22, 2020, 08:07:57 pm
content: Well, I do like turtles.It's a question of exposure.If you have a big junction block with little wires running to a smaller fuse, what happens when the far end of this war comes loose and hits the chassis?If you have the big wire going to a big piece of solid metal that is directly connected to small fuses there is not as much exposure.Look at an American style AC distribution panel.Nice big copper bars that are firmly mounted and insulated.I'm not dissing the DIN rail, there's a lot of flexibility there. I even use 'em.I just think that the power distribution bit is not something that they address well.If you were to just use the sort of busbars I mentioned above you can't have a consistent "down hill" power flow.Either the main feed breaker or the branch breakers have current flowing in the wrong direction.(Yes, I know AC goes back and forth.)

author: S. Petrukhin
author_rank: Super Contributor
timestamp: October 23, 2020, 09:25:30 pm
content: Phoenix Contact PTFIX 6/6X2,5-NS35 RD

author: S. Petrukhin
author_rank: Super Contributor
timestamp: October 23, 2020, 09:29:28 pm
content: Quote from: elekorsi on October 21, 2020, 12:45:06 pmCost as an airplane wing.

author: Kjelt
author_rank: Super Contributor
timestamp: October 23, 2020, 09:32:57 pm
content: Quote from: S. Petrukhin on October 23, 2020, 09:25:30 pmCheck the current requirements of TS. Does not match.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: October 24, 2020, 12:59:20 am
content: Quote from: Kjelt on October 23, 2020, 09:32:57 pmThis is just an example. For thicker cables and higher currents, see the 2nd photo.

author: Kjelt
author_rank: Super Contributor
timestamp: October 24, 2020, 07:04:38 am
content: You're second photo are 2,5mm2 only.TS wants to attach a 25mm2 cable .

author: S. Petrukhin
author_rank: Super Contributor
timestamp: October 24, 2020, 02:16:57 pm
content: Quote from: Kjelt on October 24, 2020, 07:04:38 amThis is a fundamental decision for understanding. There are many similar connectors for different cross-sections.I think it makes no sense to specify local Russian manufacturers whose solutions I use - they are not available on the world market.

author: Renate
author_rank: Super Contributor
timestamp: October 24, 2020, 03:06:05 pm
content: Seriously? People keep on coming up with things that connect a big wire to little wires with no protection?Why don't you just put a DIN rail clip on the Blue Sea Systems fuse block that I recommended above.It seems safer/better than anything that the DIN rail world can come up with apparently.

author: Monkeh
author_rank: Super Contributor
timestamp: October 24, 2020, 03:29:40 pm
content: Quote from: Renate on October 24, 2020, 03:06:05 pmThe DIN rail world already has the correct solution: an MCB.Many of the 'unprotected' options mentioned heredon't require additional protection.If you want to bring in a single high-current source and fuse it down to multiple outputs, you need a bus bar, as many MCBs as required, and an MCB, switch, or coupler to connect the incoming feed to the bar.

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: October 24, 2020, 03:46:36 pm
content: Quote from: Renate on October 24, 2020, 03:06:05 pmSeriously, you need to understand that current (load or fault current) needs a complete path to flow. The protection devices are there to prevent sustained fault current flow, not to prevent connecting large wires to small ones.

author: wizard69
author_rank: Super Contributor
timestamp: October 24, 2020, 07:34:07 pm
content: If anyone is about to split a feeder into multiple branch circuits, most manufactures have approved bus bar solutions for their DIN rail breakers. For example:https://www.automationdirect.com/adc/overview/catalog/circuit_protection_-z-_fuses_-z-_disconnects/ul_489_miniature_circuit_breakers/eaton_spare_parts_-a-_accessories_(faz-na_series),here is more complete catalog with engineering data:https://literature.rockwellautomation.com/idc/groups/literature/documents/sg/1492-sg122_-en-p.pdf.The Rockwell document goes a bit deeper into engineering but you can find similar documents form other vendors.In any event there are plenty of DIN rail solutions for solving the problem of multiple branch circuits. For example:https://www.amazon.com/Junction-Terminal-Computer-Splitter-Connector/dp/B084DKY6CD.Such a block might be used for neutrals in a single phase system. In a nut shell if one looks long enough you can find a DIN rail solution for every regulatory zone and engineering problem.

author: Renate
author_rank: Super Contributor
timestamp: October 24, 2020, 07:59:00 pm
content: Yes, I already acknowledged the busbar accessory solution.Still, you are stuck with full width breakers.Yes, you can find fuse holders too, but they are full width also.Moreover, it's often (in the DC world) that you want a bit of protection on branch circuits but don't really need the ability to switch them off.20 branches? 20 breakers? that's a bit of space. (20 is what was in the OP.)Hey, I've got an idea! Just get a big Wire-Nut and twist all the wires together!Solution: Make a PCB with either PTC fuses or replaceable fuses. Throw in some LEDs. Put it in a box with a DIN clip.

author: Lomax
author_rank: Frequent Contributor
timestamp: March 01, 2021, 07:06:46 pm
content: Ok, so I've been looking at terminals from Weidmuller, Wieland, Conta-Clip, and others; it seems the pitch is the same for a given size (5mm for 2.5mm2terminals, 6mm for 4mm2), and the thread size is also the same (M2.5) - but are the commoning blocks interchangeable, or does the throat depth vary between manufacturers? If I buy 100 two tier Weidmuller DIN rail terminals, can I use Wieland or Conta-Clip jumpers with them, or do I have to buy the same brand?

author: Kjelt
author_rank: Super Contributor
timestamp: March 02, 2021, 07:10:00 am
content: My experience: you have to buy the same brand and exact same series of that brand.Look in their catalogue.Even with the same brand and same pitch you have differences like screw size version, and clamp insertion version.