# Junction box and din rail w/terminals as splice method?



## micromind (Aug 11, 2007)

I've done it a lot for controls but never for power. No reason why it wouldn't work though. 

It'd make testing easier


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## gpop (May 14, 2018)

They may be rated for 30 amps but from experience i know they won't handle it. Under 20 amps with occasional spikes up to 30 should be fine.

As a industrial electrician i have installed thousands of din rail connectors and worked on 10's of thousands in plc panels. Most common fault are

1/ insulation being nipped under the screw
2/ screw not being tightened (funny when you discover the problem on a panel that's over 10 years old)
3/ thin strand wire being cut by the screw being over tightened
4/ stray stands bridging different connectors
5/ overloaded connections 
6/ some dumb arse put one or more in backwards (only one side is shielded)

I wouldn't have a problem with what you are doing and it would be my preference over wire-nuts. It would be a lot cheaper to use a 4 sq, wire nuts and a hammer.


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## glen1971 (Oct 10, 2012)

I'm with gpop. We use them all the time for power and control. The majority of the buildings I'm around have junction boxes on the sides of 'em with either conduit or cables going to end devices. And that is for everything from a transmitter, to heat trace, to lights, to small motors.


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## GFI Joe (8 mo ago)

gpop said:


> They may be rated for 30 amps but from experience i know they won't handle it. Under 20 amps with occasional spikes up to 30 should be fine.
> 
> As a industrial electrician i have installed thousands of din rail connectors and worked on 10's of thousands in plc panels. Most common fault are
> 
> ...


great insight, thanks for the reply


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## backstay (Feb 3, 2011)

Looks great.


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## SWDweller (Dec 9, 2020)

I like din rail a lot, even to the point of using din mounted fusing, and circuit breakers.
Helps a lot when you want to limit the energy going to a device. I like the CB's better as you do not have to find the right fuse.


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## Kevin (Feb 14, 2017)

Oh man,

Now I wanna use din rail for junction boxes...

I know a few junction boxes that din rail terminal blocks would have come in handy...


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## ohm it hertz (Dec 2, 2020)

This looks so satisfying. I have a service upgrade on Tuesday which would really benefit from this.


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## TEO (Jan 17, 2020)

This guy could of used a box that big


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## splatz (May 23, 2015)

ohm it hertz said:


> This looks so satisfying. I have a service upgrade on Tuesday which would really benefit from this.


If you have to pull relocate a panel and make the original panel a junction box, DIN rail makes it very easy to stay organized, and service in the future.


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## splatz (May 23, 2015)

Kevin said:


> Oh man, Now I wanna use din rail for junction boxes...


In a panel swap, extending circuits, where it's one wire to one wire, DIN mount terminal blocks would work great. 

In a junction box, where you have several wires joined, wago lever nuts and DIN rail mounts will work better.


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## splatz (May 23, 2015)

gpop said:


> They may be rated for 30 amps but from experience i know they won't handle it. Under 20 amps with occasional spikes up to 30 should be fine.


In your experience, does that apply to any particular brand, or all brands? 


gpop said:


> 1/ insulation being nipped under the screw


Very true, you can't see inside to check your work as you go. IMO I'd be nuts if I used a stripper that doesn't have a stop for the strip length with terminal blocks. 


gpop said:


> 2/ screw not being tightened (funny when you discover the problem on a panel that's over 10 years old)


Also true, you have to tug test everything twice, once when you tighten the screw, then tug them all again before you close the box. Yes, every one.


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## splatz (May 23, 2015)

TEO said:


> This guy could of used a box that big


Or replace the cover with a Rack-A-Tiers Top Hat


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## Wardenclyffe (Jan 11, 2019)

gpop said:


> They may be rated for 30 amps but from experience i know they won't handle it. Under 20 amps with occasional spikes up to 30 should be fine.
> 
> As a industrial electrician i have installed thousands of din rail connectors and worked on 10's of thousands in plc panels. Most common fault are
> 
> ...


I had a thermocouple failure because the terminal was tight, the wire wasn't under the screw, been running for quite awhile like that. landed it and that fixed it.


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## gpop (May 14, 2018)

splatz said:


> In your experience, does that apply to any particular brand, or all brands?


All brands from what i have seen. 

Lack of air space around the metal piece probably has something to do with it but its also possible that poor craftsmanship shows closer to the limits. 
We had a very high failure rate on large generators where the charger and block heater were terminated on this size of connection blocks. Im guessing 6 to 24 months before failure (being Florida with plenty of black-outs and warm weather it doesn't show up immediately that the charger of heater has failed). 
All of the panels were retro-fitted before i joined the company and there was a mis-match of different brands blocks so i can not say it was just one brand. I changed all of high amp connections to the next size up which i think are rated 40 amps plus and 3 years later we are not seeing a repeat of the problem.


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## joe-nwt (Mar 28, 2019)

Might come in handy one day to have your neutrals labeled .


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## Almost Retired (Sep 14, 2021)

Extremely handy since he has 8 hots and 4 neu's 
i would also want one of every MWBC to be a different color than the other
just makes it easier as well


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## splatz (May 23, 2015)

joe-nwt said:


> Might come in handy one day to have your neutrals labeled .


That's a very good point. I am not sure what the thinking is in the OP picture. Grouping the blacks and whites together would make sense if it was all one circuit and you were going to jumper the blocks together. You'd also be a real pain in the ass if you didn't leave a few empty spares at the end of each jumpered group. But no reason not to label the neutrals any way you look at it. 

I'd definitely group the wires by cable if I was extending the wiring to a new location, and I'd use black and white terminal blocks for black and white wires. I'd also use separators between circuits, they cost next to nothing. It would go black, white, grounding green, separator, repeat. It pays to make it as obvious as possible for the next person. (Greens are optional, a grounding block would save space on the rail and is cheaper, but you use them might as well use the ones that connect to the DIN rail.)


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## splatz (May 23, 2015)

gpop said:


> All brands from what i have seen.
> 
> Lack of air space around the metal piece probably has something to do with it but its also possible that poor craftsmanship shows closer to the limits.
> We had a very high failure rate on large generators where the charger and block heater were terminated on this size of connection blocks. Im guessing 6 to 24 months before failure (being Florida with plenty of black-outs and warm weather it doesn't show up immediately that the charger of heater has failed).
> All of the panels were retro-fitted before i joined the company and there was a mis-match of different brands blocks so i can not say it was just one brand. I changed all of high amp connections to the next size up which i think are rated 40 amps plus and 3 years later we are not seeing a repeat of the problem.


That's very good info, it's not a lot of money or space to bump up to the next size.


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## glen1971 (Oct 10, 2012)

splatz said:


> Very true, you can't see inside to check your work as you go. IMO I'd be nuts if I used a stripper that doesn't have a stop for the strip length with terminal blocks.
> 
> Also true, you have to tug test everything twice, once when you tighten the screw, then tug them all again before you close the box. Yes, every one.


I've tried the stop on my strippers once and found it to be a PITA. If you do enough of 'em you'll know how much to strip by eye.

I always tug tested everything too. Either tug or push the wires back, if the terminals are on stand-offs. I had a couple of panels where they used a style of terminal that was spring loaded and needed pressure to open the slot for the wire to go in. They were a pain.


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## joe-nwt (Mar 28, 2019)

glen1971 said:


> I had a couple of panels where they used a style of terminal that was spring loaded and needed pressure to open the slot for the wire to go in. They were a pain.


You're talking about the ones that need a small flat blade to activate? All of the biomass boilers (european) I install and service come with those terminals. Once you get used to them they aren't that bad. Some of the panels even come with a bent shank for the really tight panels.

Similar to this


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## Kevin (Feb 14, 2017)

glen1971 said:


> I had a couple of panels where they used a style of terminal that was spring loaded and needed pressure to open the slot for the wire to go in. They were a pain.


We've got a few boxes of them at the office... they bought them before I started working there.... they're useless for what we're doing.

Screw terminals all the way!


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## splatz (May 23, 2015)

glen1971 said:


> I've tried the stop on my strippers once and found it to be a PITA. If you do enough of 'em you'll know how much to strip by eye.
> 
> I always tug tested everything too. Either tug or push the wires back, if the terminals are on stand-offs. I had a couple of panels where they used a style of terminal that was spring loaded and needed pressure to open the slot for the wire to go in. They were a pain.


Did you ever try this type? Really a game changer IMO


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## joe-nwt (Mar 28, 2019)

splatz said:


> Did you ever try this type? Really a game changer IMO
> View attachment 169940


Yeah those work great if you only do one type of terminating all day and need the same length of stripped conductor every time. 

I've tried the type you posted, never really got used to them I guess. I have several pairs of the Ideal style, all of them have the insulation stop removed. I also strip by eye.


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## Breakfasteatre (Sep 8, 2009)

I try to intall din rail and terminals when extending power feeds in the industrial environments that I work in. Our customers are constantly re-arranging equipment so we end up extending power feeds often. I go for the oversized terminal blocks that are good for like up to #4 or #6 wire. wdu6 i think is the partnumber from weidmuller

The spring loaded terminal blocks remove alot of the potential issues with the screw terminal blocks. Consistent pressure on the connection, very easy to check if the wire is in as you push it in and then can easily pull on it once you let go of the spring tensioner.

All equipment coming from europe is all spring loaded terminals it seems.

We stock weidmuller screw terminal blocks at the shop, but if i get a chance, i order the spring loaded ones. I also like the spring loaded ones where the wire is terminated on the front of the block, saves room, and the 3 and 4 wire versions are smaller than the screw terminal block equivalent.


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## splatz (May 23, 2015)

joe-nwt said:


> Yeah those work great if you only do one type of terminating all day and need the same length of stripped conductor every time.
> 
> I've tried the type you posted, never really got used to them I guess. I have several pairs of the Ideal style, all of them have the insulation stop removed. I also strip by eye.


That's true they are not always worth the space, doing general maintenance or troubleshooting or etc., regular strippers are fine. Terminating at a panel, or a bunch of receptacles, or whatever - then to me it pays, faster, easier, more consistent. In the shop, I'll set out the Knipex set for the terminal blocks, and the Felos set out for screw terminals, and of course regular strippers too, but 90%+ of the strips will be with the automatics.


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## macmikeman (Jan 23, 2007)

I'm designing my new invention that allows you to cut wire at any six inch incrementation along the dots and then pull the insulation off like when you are installing a Firex smoke detector. Rolls will be 500 feet like standard but you will have choice of 3/8 inch pre cut hand pull insulation removal or 5/8" for when you wrap around a terminal. Just think how fun it will be having to carry duplicate rolls of the same color on your truck once I set the industry standard. I'll release it as soon as I can figure out a way to get it into code mandatory................... Nyuck Nyuck...


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## joe-nwt (Mar 28, 2019)

Another good application for din rail/blocks and panduit is for dressing up zone valve wiring. Looks 100% better than wads of LVT and orange wire nuts.


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## glen1971 (Oct 10, 2012)

splatz said:


> Did you ever try this type? Really a game changer IMO
> View attachment 169940


I've been using these for years and am pretty used to them.


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## GFI Joe (8 mo ago)

splatz said:


> That's a very good point. I am not sure what the thinking is in the OP picture. Grouping the blacks and whites together would make sense if it was all one circuit and you were going to jumper the blocks together. You'd also be a real pain in the ass if you didn't leave a few empty spares at the end of each jumpered group. But no reason not to label the neutrals any way you look at it.
> 
> I'd definitely group the wires by cable if I was extending the wiring to a new location, and I'd use black and white terminal blocks for black and white wires. I'd also use separators between circuits, they cost next to nothing. It would go black, white, grounding green, separator, repeat. It pays to make it as obvious as possible for the next person. (Greens are optional, a grounding block would save space on the rail and is cheaper, but you use them might as well use the ones that connect to the DIN rail.)


Great input. I will definitely do it that way, makes a TON more sense


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## micromind (Aug 11, 2007)

glen1971 said:


> I've been using these for years and am pretty used to them.
> View attachment 169944


Those look very much like the Stripmaster ones I have. I even have a pneumatic model, saves time and sore wrists when I have a bunch to strip.


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## joe-nwt (Mar 28, 2019)

micromind said:


> Those look very much like the Stripmaster ones I have. I even have a pneumatic model, saves time and sore wrists when I have a bunch to strip.


You get sore wrists from stripping wire?


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## paulengr (Oct 8, 2017)

With DIN rail terminal blocks you can easily get any size. Erico makes some up to 1000 MCM!! I will say flat out though that when we used them for 500 MCM the clips weren’t very sturdy. We had to shape the wire a lot. These are listed as power distribution blocks. Just be careful to watch out for tap rule violations because it’s easy to accidentally do it.

The little 5 mm ones rated for #12 are limited to 20 A. The 6 mm ones are rated 30 A. They look very similar. Did you get the right ones?

Also they are supposed to be one wire per terminal so distribution is an issue. If you want to do more use the premade jumpers. When you do this if you use both sides you get 2 terminals for each jumper segment.

If you want to go crazy on distribution you can also look at bus bars like these:









Power Distribution Connection Module, 4 bar, 160 Amps, 14 connection points per bar - ASI


Power Distribution Connection Module, 4 bar, 160 Amps, 14 connection points per bar




www.sourceasi.com





With either one Wago DIN style has a funky vertical connection so you have to curl them back down. OK I guess for marshaling panels though.

For breakers I really like the Eaton FAZ series which is just a bolt in bus bar (1, 2, or 3 phase). This is a lot more compact than a traditional distribution panel. It is UL 489 in B/C/D types.


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## joe-nwt (Mar 28, 2019)

paulengr said:


> Also they are supposed to be one wire per terminal so distribution is an issue. If you want to do more use the premade jumpers. When you do this if you use both sides you get 2 terminals for each jumper segment.


You know, I have never considered the one wire per terminal thing before and have wired scads of panels with more than one wire. I do like the factory jumper bars and use them where ever practicable. but you had me concerned with your statement so I dug this out of the Weidmuller catalogue.

"Two conductors at a contact point You achieve assignment to individual circuits, identification and division of individual functional units optimally by only connecting one conductor to each contact point. *Terminal blocks with screw connection (W-Series) are available to you should two conductors of the same cross-section be connected to a contact point. The connection of two cables with screwless contact points is forbidden according to DINĂIEC* 0-. Connection of two conductors is possible in terminal blocks with spring connection, however, by using twin wire-end ferrules."

So is that the defining thing for more than 1 wire, screw terminals?

Let me know what you think.


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## splatz (May 23, 2015)

joe-nwt said:


> You know, I have never considered the one wire per terminal thing before and have wired scads of panels with more than one wire. I do like the factory jumper bars and use them where ever practicable. but you had me concerned with your statement so I dug this out of the Weidmuller catalogue.
> 
> "Two conductors at a contact point You achieve assignment to individual circuits, identification and division of individual functional units optimally by only connecting one conductor to each contact point. *Terminal blocks with screw connection (W-Series) are available to you should two conductors of the same cross-section be connected to a contact point. The connection of two cables with screwless contact points is forbidden according to DINĂIEC* 0-. Connection of two conductors is possible in terminal blocks with spring connection, however, by using twin wire-end ferrules."
> 
> ...


This varies brand by brand. I know that the Automation Direct Konnect-Its specifically say only one wire per terminal. But if you look at the mechanism, you'd have a pretty hard time getting worried about putting two #14 or #16 stranded wires in there. 

BTW - I found some crimp terminals allow two wires as long as the circ mil combined is in the range of the terminal - so you can put two #14 in the #10-12 in that brand and it's 100% compliant. Very handy IMO.


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## micromind (Aug 11, 2007)

My Allen Bradley book has a wire size table that allows more than one wire in a number of screw type blocks. 

For example, I use a lot of J4 blocks, 4 - #20 or 22 are allowed, 3 - #18 or 16, 2 - #14 and 1 - #12 or #10. The J70 will take 1 - 3/0 or 5 - #14, 12 or 10s. 

The spring blocks allow only 1 wire per terminal.,


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## Breakfasteatre (Sep 8, 2009)

for the times when i cant fit more terminals and jumpers in, i use a special ferrule which goes over two stripped wires. I call it a double ferrule, which is what it might actually be called


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## paulengr (Oct 8, 2017)

joe-nwt said:


> You know, I have never considered the one wire per terminal thing before and have wired scads of panels with more than one wire. I do like the factory jumper bars and use them where ever practicable. but you had me concerned with your statement so I dug this out of the Weidmuller catalogue.
> 
> "Two conductors at a contact point You achieve assignment to individual circuits, identification and division of individual functional units optimally by only connecting one conductor to each contact point. *Terminal blocks with screw connection (W-Series) are available to you should two conductors of the same cross-section be connected to a contact point. The connection of two cables with screwless contact points is forbidden according to DINĂIEC* 0-. Connection of two conductors is possible in terminal blocks with spring connection, however, by using twin wire-end ferrules."
> 
> ...


UL basically states no more than one wire per terminal unless designed for it. You are referencing EU standards but it’s pretty universal. Aside from Code I’ve dealt with many terminal blocks that are overstuffed and wiring falls out or has some kind of problem but you still see daisy chained jumpers that are clearly illegal. I switched to #16 because it fits better then just started using the factory jumpers. When you consider that most of the time in panel building is just landing wiring why waste labor to save a few pennies? What I’ve found over time is that any kind of premade assembly or connector or modular system costs more for materials but drives labor costs down. Even with costs today labor dominates wiring on most jobs especially panel building. Take for instance “remote terminal blocks” or “zip links”. How much time does it take to run 10-20 wires from a PLC card to a set of terminals? Those “convenient” prewired terminal blocks are expensive but it reduces the wiring time in half because now I’m only wiring up devices or at least not messing with a lot of very high density wiring.

Wire nuts and split bolts obviously take a lot more wires. There are some specialty “double wire” devices but a factory jumper is much easier. Most “double wire” ferrules I’ve seen are just that…a ferrule that is overstuffed. Most have broken strands and fail over time. Maybe it’s just me but after over 20 years in mining and heavy industrial plants I tend to build my equipment to “last forever”.

The only exception I can think of is using lugs. You can usually stack at least 2 lugs without special stacking adapters or stackable lugs. You can usually install them “back to back”. Stacking 90 degrees apart it can be pushed to 3 lugs and if you have access to the back side of a bus bar or it has 2 or 4 holes even more can be done. I’m not thinking of control wiring here. When you get into 500-1000 HP low voltage motors quite often the equipment designers completely ignore the challenges associated with it.


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## joe-nwt (Mar 28, 2019)

Breakfasteatre said:


> for the times when i cant fit more terminals and jumpers in, i use a special ferrule which goes over two stripped wires. I call it a double ferrule, which is what it might actually be called




I keep some of those doubles in my kit as well. I only use them as a last resort though, for that purpose they work well. Most often on a device rather than a terminal block.


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## Wardenclyffe (Jan 11, 2019)

These point I/O's are ok with spring clips


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## htneighbors (Jan 23, 2009)

I've installed tons of din rail and TBs over the last couple of decades. I much prefer TBs in Jboxes over wirenut spaghetti! 
PS: Solid wire in TBs can be a pain when not torqued properly.


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