Spring clamp vs. screw type terminal blocks

My final comment is to just make sure the electricians terminating spring clamp terminals understand how to do it properly.

I prefer the screw clamps for this very reason. I worked 3 years with a guy on the shift ahead of me that couldn't figure out how to get a wire in a spring clamp without it either falling out, or being in so far that the clamp was on the insulation not the wire. Of course he was better than the guy who wired a small control box using StaCons and never crimped any of them...o_O


Bubba.
 
For me spring clamps or "cage clamps" as they are sometimes called.

The problem with the electrician not understanding how to use cage clamps is IMO positively offset by the fact that you can see what you are doing due to that you usually insert the wire from the front.
On screw terminals you insert the wires from the side so you are effectively doing it blind. Have experienced numerous problems due to wires inserted wrongly.

For screw terminals I have also experienced plants where the local electrician failed to tighten the screws on every single terminal. With cage clamps, at least they are self tightening.

Dont group cage clamp terminals together with push-in terminals. I love cage clamp, and I hate push-in terminals. Sadly, push-in terminals seems to be the new standard in PLC I/O cards.
 
For me spring clamps or "cage clamps" as they are sometimes called.

The problem with the electrician not understanding how to use cage clamps is IMO positively offset by the fact that you can see what you are doing due to that you usually insert the wire from the front.
On screw terminals you insert the wires from the side so you are effectively doing it blind. Have experienced numerous problems due to wires inserted wrongly.

For screw terminals I have also experienced plants where the local electrician failed to tighten the screws on every single terminal. With cage clamps, at least they are self tightening.

They need a new electrician! These are non-issues to somebody paying attention.
I hate broken spring terminals!
Screw terminals always!
 
For me spring clamps or "cage clamps" as they are sometimes called........The problem with the electrician not understanding how to use cage clamps is IMO positively offset by the fact that you can see what you are doing due to that you usually insert the wire from the front.
Group cage clamp terminals together with push-in terminals. I love cage clamp, and I hate push-in terminals. Sadly, push-in terminals seems to be the new standard in PLC I/O cards.

Jesper, What is the difference between spring clamp/cage clamp terminals & push-in terminals?

I’ve always used those terms interchangeably.
 
In the push-in terminals you do not have to insert a screwdriver to open the clamp.
If you use stiff wires or wires with ferrules you can literally just push the wire in.

The spring force of the tab that gets pushed in is very weak. The only thing that keeps the wire in place is the sharp edge on the tab that gets pushed in. It is very easy to deform the tab since it is quite flimsy. It just takes that you insert the wire at too steep an angle, or wiggle the wire a bit. And you wont know that the tab has been weakened since it is very hard to see.

The spring force in a cage clamp terminal is much stronger. And the design is generally much more robust. It is possible to damage a cage clamp terminal, but it takes some deliberate force to do so.

Also, with push-in terminals you can squeze 50% more wire ports in the same space as you can with cage clamp or screw terminal. So the PLC manufacturers are using this "advantage" to squeze ever more channels into the same space. We have 16-channel modules where in the past we would have 4 or 8-channel modules. This is an improvement that I did not ask for.
 
Over time I have moved from screw terminal to spring clamp/cage clamp style.
I find them easier to wire, and to many times i have had to troubleshoot and fix wires that were landed on the insulation from screw terminals.

Also I have noticed during shipping of some machines some of the screw terminals have loosened, probably because they weren't landed correctly from the beginning.

Also in tight ductwork the spring clamps give more room for your fingers since they are on more of the front of the block as opposed to the top and bottom like screw terminals.
 
I prefer screw terminal connections.

Industrial control wiring is stranded-wire. If it were solid wire, the push-in clamp style would be perfect (like a bread-board in digital electronics). If you use push-in clamp terminals, ferrules are a must IMO.

The best of both worlds are the clamps like you would see on an Allen Bradley 1606 power supply. They have a physical lever that clamps the wire shut. It isn't feasible on many other applications, however.
 
I moved into engineering and design and my opinion changed after using Wago & Phoenix spring clamp terminals for control wiring (stranded #16 & smaller) on some industrial panels. The connections seemed to hold up well and it was a space saver in the panels because less space is required between the terminals and the wiring duct.


We have been using these for many years, in my experience they are faster to use and more reliable than screw type terminals. The spring determines the force on the connection, no more electricians either fastening too hard, too loose, or forgetting to properly fasten entirely. Cage clamps are resistant to vibration. Screw terminals need to be checked and retightened on a regular basis, which just does not happen. For this reason spring clamp terminals are a requirement in some sectors. Railways, ships spring to mind (pun intended), just about anything moving or vibrating.
 
My background started in industrial maintenance. Even if a spring terminal is rated for so many insertions, the plastic degrades so by the time I have to get in the panel pushing a screwdriver in to release usually cracked the plastic.

I even have to work on small relatively new Mitsubishi VFD's with spring terminals and even the customer has taken to cutting the wires a few inches out instead of trying to get the wire out, then using a handfull of wire nuts to reinstall.

+1 screw terminals only!
 
Changed from screw terminals to spring terminals, will never go back.

To many failures with screw terminals, either loose connections or spread, broken terminal housings due to overtightening.

I have only has a tiny number of failures with spring terminals and they are obvious at the install unlike with loosening screw terminals.

Wiring is also WAY faster with spring terminals.

Cheers

Ken
 
I'm just curious - with regard to UL certifications - usually you need a torque screwdriver / etc for screw terminals.

I'd imagine that all goes away with push-in or spring terminals. That would probably be worth it alone for those doing UL listed panels.
 
I'm just curious - with regard to UL certifications - usually you need a torque screwdriver / etc for screw terminals.

I'd imagine that all goes away with push-in or spring terminals. That would probably be worth it alone for those doing UL listed panels.
It's true.
 

Similar Topics

anyone in need of some schneider atv31's 208V 3 phase 1/2 hp drives? magelis touch screen modbus hub phoenix ethernet switch LMC20 motion plc et al?
Replies
0
Views
1,199
I am building a machine , and I have 3 Air Springs ( Air Bags ) that need to Inflate and Deflate very quickly. What type of valve do you recommend...
Replies
5
Views
3,113
In cleaning out I found two new AB Bulletin 2707-NC1 cables. Anyone need one? Olias
Replies
6
Views
2,100
Hi just a question, does a 4/2 valve with coil on one side and a spring return on the other side, but not a 3/2, a 4/2 does it exsist ?
Replies
2
Views
2,126
Wife is making me clean out my parts room (to her it is junk) Well I found some boards,and for the life of me I ca'nt remember what they are...
Replies
8
Views
2,463
Back
Top Bottom