Do push-in connections actually overheat?

[RossS]

Having spent the better part of the afternoon trying to chase this down and basically getting nowhere, I thought I'd post this here.

There's a ton of opinion out there, and a whole lot of it is consistent with my own opinion that push-in type connections are not as electrically or mechanically sound as screw type, including wire nuts. But when I went looking for actual evidence, you know, like studies and such by groups that get paid to destroy stuff, I came up empty.

Can anyone point me to an actual study, preferably by a nationally recognized testing laboratory, of how well push-in type connections perform and whether they tend to overheat under higher load conditions?

Just to clarify, this is my actual question: "Can anyone point me to an actual study, preferably by a nationally recognized testing laboratory, of how well push-in type connections perform and whether they tend to overheat under higher load conditions?"

 

[zbang]

You could start with the applicable listing specs and ask how those were developed. I suspect that the NRTL will ask for some dollars to see that.
You also need to define "higher load conditions", does that mean under, at, or over the rated current?

 

[ptonsparky]

I had an oops hooking up a .5 KVA transformer in my shop a few weeks ago.
24 volt secondary. I can verify that the insulation on the conductor smoked and not the lever lock connection.

Under normal usage I don't see an issue.

 

[jim dungar]

Stab type for sure; if by spring type you mean wire nuts, no, not looking for those. And I couldn't find engineering type drawings/diagrams of the different types of WAGOs. I assume the push-in are just like stab type, but I'm not sure about the lever type.

No.
I have probably misused the term 'Spring style' which nothing like the wiring device 'stab-in'. The spring-cage style have been used for more than 40 years, and appear to now be called 'push-in' by Wago along with their original 'Cage Clamp'.

 

[readydave8]

Your picture has a code violation!

I thought was a mirror image

 

[readydave8]

I bought a thousand or so Ideal version 20-25 years ago

Not to confident in beginning, mixed a few in here and there to see how reliable they were

The only failure I remember was due to wire not completely pushed in, or worked its way back out while twisting wires to fit crowded box

Still don't use in damp locations, crawl space, etc

Don't know how many I've used, when 1st batch used up started buying by the 100

 

[RossS]

You could start with the applicable listing specs and ask how those were developed. I suspect that the NRTL will ask for some dollars to see that.
You also need to define "higher load conditions", does that mean under, at, or over the rated current?

Approaching rated current, continuous.

 

[RossS]

You could start with the applicable listing specs and ask how those were developed. I suspect that the NRTL will ask for some dollars to see that.
You also need to define "higher load conditions", does that mean under, at, or over the rated current?

What do you mean by "applicable listing specs," AIA MasterSpec or UFGS (which, if you're unfamiliar with it, is a federal version of the same sort of thing)? I've thoroughly scoured the UFGS and found nothing; my clients are mostly federal so I'm focused on that. But the MasterSpec would be a good place to get a lead, so I'm going back to that to dig a bit deeper. So far, it's only pointing me to things like MC connectors, pin connectors, etc., but I'm still digging.

 

[RossS]

Another factor to consider is also if the wire connection is listed then it faced destructive testing. Wago and Ideal products are fairly respected even with their push ins when in the past installer error and other issues causes some concern for some people

That's what I've assumed, and that's what I'm hunting for. I'm surprised I haven't found it online. I've reached out to WAGO and am waiting to hear back, that could take a while - my request will probably catch them off guard. I'll probably have to reach out to ABB, Hubbel and/or Ideal as well, especially if I never hear back from WAGO.

 

[jim dungar]

This of course may be slightly over exaggerating the push type connection, but it gets the point across.

Actually you may be underestimating some styles.
Some push-in connectors, like wirenuts, actually push the conductor against a conductive surface while others, like wiring devices, do not.

 

[jim dungar]

That's what I've assumed, and that's what I'm hunting for. I'm surprised I haven't found it online. I've reached out to WAGO and am waiting to hear back, that could take a while - my request will probably catch them off guard. I'll probably have to reach out to ABB, Hubbel and/or Ideal as well, especially if I never hear back from WAGO.

I agree that it is very difficult to find third part analysis of the connectors.
I was able to find this link to a Wagon brochure that refers to testing to EN60068-2 standards

https://www.wago.com/medias/Technology-60290890.pdf?context=bWFzdGVyfGRvd25sb2Fkc3wxODY1Njc4fGFwcGxpY2F0aW9uL3BkZnxhRFUyTDJobE1DOHhNakl6T0RrNE5UQXdNekF6T0M5VVpXTm9ibTlzYjJkNVgxODJNREk1TURnNU1DNXdaR1l8MTg2OTY3ZTg5ZTI1ODFmNGNlNmNlMDE5MGE3MjUxMTliMjgwMTQ1NTY0MTA0NTJkY2ViNGZlNDk0ZDRmMmIxYg

 

[zbang]

What do you mean by "applicable listing specs,"

Maybe start with the ones listed here- https://www.wago.com/us/guidelines

Approaching rated current, continuous.

I'd call that normal conditions.

 

[retirede]

Having spent the better part of the afternoon trying to chase this down and basically getting nowhere, I thought I'd post this here.

There's a ton of opinion out there, and a whole lot of it is consistent with my own opinion that push-in type connections are not as electrically or mechanically sound as screw type, including wire nuts. But when I went looking for actual evidence, you know, like studies and such by groups that get paid to destroy stuff, I came up empty.

Can anyone point me to an actual study, preferably by a nationally recognized testing laboratory, of how well push-in type connections perform and whether they tend to overheat under higher load conditions?

Serious question. How do you decide which devices /equipment require your review of a laboratory study before you’ll use it?

 

[RossS]

Serious question. How do you decide which devices /equipment require your review of a laboratory study before you’ll use it?

Fair question, it almost never happens (this is my first), but in this case these type connectors came into use well after I hung up my tools, so I don't have the personal experience with them. My experience with back-stab receptacles and switches is mixed. My gut feeling has always been that a properly installed screw connection is always better. But when I was being pushed for speed, I welcomed them.

So what triggered this investigation is contractors submitting these type devices to use on federal jobs, and the UFC/UFGS don't approve or disapprove them, putting me - as engineer of record, in the position of having to decide.

I wish I could use their position on the back-stab switches and receptacles as a guide, but they're ambiguous there. For receptacles, one of their two approved terminal types is "solderless pressure type having suitable conductor-release arrangement," but in switches it's an optional type. Plus, that seems like a bit of a strange description and I'm not at all sure I know exactly what they're talking about. It seems like maybe they're talking about the push type, but I'm just not sure. Anybody?

 

[ptonsparky]

These Wago, release. Pricey but nice .

 

[Fred B]

View attachment 2571480
These Wago, release. Pricey but nice .

I like these for wiring up lighting especially if I'm up on ladder trying to hold the light up while making up the connection.
Also great for temp lights.

 

[retirede]

Fair question, it almost never happens (this is my first), but in this case these type connectors came into use well after I hung up my tools, so I don't have the personal experience with them. My experience with back-stab receptacles and switches is mixed. My gut feeling has always been that a properly installed screw connection is always better. But when I was being pushed for speed, I welcomed them.

So what triggered this investigation is contractors submitting these type devices to use on federal jobs, and the UFC/UFGS don't approve or disapprove them, putting me - as engineer of record, in the position of having to decide.

I wish I could use their position on the back-stab switches and receptacles as a guide, but they're ambiguous there. For receptacles, one of their two approved terminal types is "solderless pressure type having suitable conductor-release arrangement," but in switches it's an optional type. Plus, that seems like a bit of a strange description and I'm not at all sure I know exactly what they're talking about. It seems like maybe they're talking about the push type, but I'm just not sure. Anybody?

I appreciate the answer.

FWIW, I view push-in connectors vs backstabbed devices as completely different designs. The devices have proven to be (at least somewhat) problematic, while the connectors seem to have a good track record. I have not reviewed (or even looked for) any official testing of either.

The fact that a screw connection is better, does not necessarily mean that an alternative is not sufficiently robust for a given application.

 

[mtnelect]

I bought a thousand or so Ideal version 20-25 years ago

Not to confident in beginning, mixed a few in here and there to see how reliable they were

The only failure I remember was due to wire not completely pushed in, or worked its way back out while twisting wires to fit crowded box

Still don't use in damp locations, crawl space, etc

Don't know how many I've used, when 1st batch used up started buying by the 100

You know that it's not a labor sating device, when you have to go back !

 

[Fred B]

Wago Test

 

[jmellc]

View attachment 2571480
These Wago, release. Pricey but nice .

These are excellent for locations where lights may be changed frequently. Can remove the lead while others stay connected. Good for stranded or solid. On devices, stabs are never good IMHO. I've replaced lots of devices burned by stabbing. Very few burned from screw connections. On top of that, many were "protected" by AFCI breakers.