compression lugs vs. ring tongue lugs

[Designer69]

is there any difference between the two?

looks to me like they are the same thing

 

[petersonra]

usually the difference is that when people say ring tongue terminals they mean something intended for smaller size wires, maybe approximately <#6, where as compression lugs usually refer to similar style terminals for larger wire sizes.

You are right that they don't look all that much different, other than physical dimensions.

I kind of distinguish between them based on whether you can crimp the temrinal with the single hand crimpers or you have to get the big crimper out that takes two hands.

 

[Jraef]

Well if they both have ring tongues, then they are the same in that single regard, but only that. There is a big difference in the termination technology.

In a compression lug, you have a specific amount of pressure that is expressed on the connector and conductor, theoretically to form a solid mass without voids that could lead to corrosion and resistance. In the process, the die of the compression tool leaves a specific mark that is only impressed AFTER the proper amount of compression pressure is applied, giving an inspector a visual indication that the lug is applied correctly.

A crimp ("Sta-Kon") type ring lug just relies upon a simple indentation on the copper lug body to flatten out and make contact with the conductor. Much less accurate, no true indication that is was done correctly etc. etc. I can't tell you how many crimp terminals I have found in troubleshooting where the installer forgot to strip the wire properly (or at all) and crimped onto the insulation. The ring tongue lug had the proper dent in it, but there was LITTLE OR ZERO connectivity. That could never happen with a compression lug. But the technology for compression lugs is way too expensive to apply to small conductors.

There is also a HUGE difference in pull-out strength. I think it's been shown that if you try to pull a conductor out of a compression lug, the conductor itself will fail first, but on a crimp lug, they pull out relatively easily.

 

[Besoeker]

In a compression lug, you have a specific amount of pressure that is expressed on the connector and conductor, theoretically to form a solid mass without voids that could lead to corrosion and resistance. In the process, the die of the compression tool leaves a specific mark that is only impressed AFTER the proper amount of compression pressure is applied, giving an inspector a visual indication that the lug is applied correctly.

A crimp ("Sta-Kon") type ring lug just relies upon a simple indentation on the copper lug body to flatten out and make contact with the conductor. Much less accurate, no true indication that is was done correctly etc. etc. I can't tell you how many crimp terminals I have found in troubleshooting where the installer forgot to strip the wire properly (or at all) and crimped onto the insulation. The ring tongue lug had the proper dent in it, but there was LITTLE OR ZERO connectivity. That could never happen with a compression lug. But the technology for compression lugs is way too expensive to apply to small conductors.

There is also a HUGE difference in pull-out strength. I think it's been shown that if you try to pull a conductor out of a compression lug, the conductor itself will fail first, but on a crimp lug, they pull out relatively easily.

I have seen the simple hand-operated crimp tools that I think you are referring to.
We do a lot of panel wiring and, for small wiring, we use ratchet type tools that have to go through the full crimping cycle before release.

They are not exactly cheap - about $50 - and we use them for terminals like this:

All the tools have serial numbers and are regularly assessed for correct operation. This is done on a calibrated test rig where a number of crimps are tested for strength.

 

[Jacob S]

There is also a HUGE difference in pull-out strength. I think it's been shown that if you try to pull a conductor out of a compression lug, the conductor itself will fail first, but on a crimp lug, they pull out relatively easily.

Although it was not scientific, years ago when I got my first AMP ratcheting crimper, i performed tests on 16, 18, and 14 gauge wire with their appropriate butt connectors or ring terminals screwed together to test pull out strength (I know, kind of strange, but I was curious). I used large woodworking clamps to spread apart "U's" of wire crimped together and I found in pretty much every case, the wire failed first. I was quite surprised. It does go to show that using the correct crimpers, dies, and terminals will go a long way in ensuring that small crimp connectors make a solid reliable connection.