Mundane discussion of DIN rail Terminal Blocks

[jraef]

I would like to hear people's impressions on the subject of "Spring Clamp" style terminal blocks vs "Screw / Box Clamp" style, as well as "Insulation Displacement" style for mounting on to DIN rail. Here on the West Coast (USA), I know of nobody who likes or uses the spring-clamp style, nor the insulation displacement style. Everyone wants and uses the screw clamp style terminals.

The general verdict around here on spring clamps is that they are difficult to use if you do not have the exact screwdriver it takes to open them. They fear that sooner or later someone will attempt to make a change with the wrong tool and damage the block. There is also a general distrust of the long term reliability, even though the data from IEC users is that they are MORE reliable than screw clamp types. I tried some Wago spring clamp blocks a while ago and I had the entire project rejected by Boeing as being unsuitable for their environment until I changed out all 2000 terminal blocks to screw clamp style.

As to insulation displacement styles, these are relatively new around here and the mistrust runs deeper. People tend to associate them with the cheap lamp plugs that you stab on through the insulation of Zip cord, so they don't want to trust anything industrial to that kind of technology.

Comments or opinions?

 

[itsmoked]

Hey Skogs; Do you have a link to a typical IDC you'd be referring to?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Skogsgurra]

This is a typical one.

http://www.electusdistribution.com.au/images_uploaded/IDCconnE.pdf

I cannot say for sure if these are the good ones. What I have used and seen used are Berg, T&B, Cannon and other well-known brands. T&B may not be with us any more but their connectors still work.

This is what it looks like in the crane application:

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[itsmoked]

Ha! I use those by the case and always call them IDC!

I thought you meant something else for point to point wiring.

I really like T&B's stuff.
Thanks.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[jraef]

Keith,
These are the ones I was thinking of. The are individual blocks for DIN rail mount and require no special tools other than a screwdriver blade narrow enough to fit in the slot. Available from Phoenix, Entrelec, Wiedmuller also, maybe others.

IDC terminal blocks (note: PDF starts off at 154% view. Reduce the view size for easier scrolling)

 

[rovineye]

I have wagos by the gross throughout my plant. Lots of problems. Problems are related to the constatnt disconnecting and reconnecting of the wires because we test things to death. Particularly true on our engines. Not trying to stir that all up again. Just a numbers thing. The more times a wire is disconnected, the greater chance of it breaking, or a strand not making it in and shorting. HT wire seems to be the worst.

We don't use ferrules (thimbles) at all. How many of you do use them?

Where we use spring clamp terminals on large power cables, we have no issue at all, but no one gets in to mess with those, and access is much better.

I have a requirement that my equipment come with connectors complying with ANSI/UL 486A-1991. I don't know if these do, and I have never checked. Mostly because I don't want to know the answer I guess. Changing out tens of thousands of connectors doesn't sound like fun to me.

 

[itsmoked]

rovineye; That pretty much concurs with Scotty's assessment. Sounds like if you want to regularly disconnect wires and reconnect them then both 'bare' wire solutions, spring, or cage, have a wear-an-tear issue. Go with crimped on spades so you don't actually undue/re-due the wire connection, but rather, the 'once removed' circuit connection(spade).

Thanks jraef; looks like even less hassle than the standard spring ones!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[controlsdude]

spring cage - wago's are too weak, never use them
spring cage - phoenix are a lot better
but spring cage has its drawbacks, You can clamp down on the insulation, even if you pull the wire to make sure.
If your using wires that have the nipple clamped on, spring cage can not bit into this metal nipple and hold it.
I believe it takes more time to to terminate spring cage then a screw terminal.

Screw terminal - only drawback - have to retighten maybe every quarter or semi annually if you have a lot of vibration.

 

[RAH1234]

From the production end of it, our guys love building systems with the spring clips. From the perspective of maintaining the equipment it is a different story.

Among the other things already mentioned, access to the spring-release notch is often difficult. In an industrial environment, I don't want my guys sticking both hands into the multiple wires coming from the terminal strip to pry open a spring clip- I'd rather they have better control over what they're touching by having straight-on access with an insulated screwdriver.

Unless there is significant thermal cycling or vibration, I typically specify screw terminals. The key to eliminating loose connections is to re-tighten them during a regular bi-annual P.M.