Push in connectors use a different clamping means than backstabs on devices. They are easy to ensure the connection is secure for a DIY. Some also like the Wago Lever connectors.

 

I used to use Ideal (brand) push in connectors until I found WAGO lever nuts.

 

Keep in mind that none of them are allowed for open-air splices. Any use of any of these must occur inside a junction box, with the usual rules applying - cable clamp, 1/4" of sheath coming into the box, 6" of free wire beyond the sheath.

 

Any recommended box size : 1 gang octagon or 2 gang square or ? I have seen octagon jct boxes mounted to the side of the rafter. I will also use insulated cable staples.

 

I love them......Want a good price on a tool box full of wirenuts....gimme a call.?

 

Don't go crazy. WAGOs have their place but you still need wire nuts. WAGOs are good for #12 and smaller wires but you need other connectors for larger wires. Yes I know they make a WAGO for number #10 but I (as a personal preference) do not use WAGOs on high amperage circuits.

 

Are the push in connectors with no lever also better than wire nuts? Better than backstab connections on receptacles, etc.?

 

The push in has much more contact area than a backstab.

 

One of the major advantages of the Wago over backstab is a much more consistent pressure on the wire which is what the mechanical connectors are all about.

 

Some videos of Wago tests by DIYers that might be of interest. (Right up quatsch's alley!)

Resistance measurements of Wago vs wire nuts (see data summary at 13:30)

Thermal imaging under heavy overload:

Heat and flammability tests:

 

Also, Wagos do take up a bit more space in the box.

 

The backstab has an edge of spring like material pressing against the round conductor. The push in has 2 flat surfaces in contact with the conductor along the stripped length.

 

Between what points were those measurements taken? How were variables like torque eliminated? How was contact area calculated? Contact area will be different depending on wire sizes and combinations and wire connector sizes.

 

I have some Wagos that I use especially when there are multiple wire connections in the box and it's not a simple circuit. They take less space than wire nuts and can sometimes eliminate the use of an extra wire nut if you need to pigtail something. They are very expensive though (relative to wire nuts) and wire nuts are really easy to use for simple circuits, so I save the Wagos for difficult circumstances. I also use this style of connector when aluminum gets mixed in.

https://www.lowes.com/pd/Alumiconn-3-Port-Al-Cu-2-Pack-Purple-Al-Cu-Wire-Connectors/4433877

 

To clarify:

For reference, here's some numbers, best to worst. Lower is better. All solid, no stranded conductors.
Resistance depends on pressure & mating surface area

Main Panel connections, 23 uOhms,
so high pressure & high area is the
meaning I pull out of this number.

outlet screws, 165 uOhms
high pressure & high area

Wirenut, 440 uOhms
med press? & medium area?

backstab, 720 uOhms
low pressure & low area

plug/socket, 5 mOhms
low pressure & unknown area

I don’t know how these values
hold up over time except for backstabs,
which don’t seem to hold up well.

 

With so many variables and unknowns what do those number actually mean?

 

I think his point was just that all else being equal, backstab have a measurably higher resistance (impedence) which indirectly helps explain why they're less reliable (i.e. low pressure and low area). And that's assuming the backstab mechanism works perfectly, which it doesn't. How well the wire nut and outlet screws work is more a function of how well the installer uses it, whereas with backstabbing, you can be an expert backstabber but the mechanism just sucks, which is out of your control.

 

I can tell you, I've never seen a melted wago in a box. I've definitely seen wirenuts fail.

 

You're kind of comparing apples to oranges there - "fail" vs. "melt". Have you seen a wire nut melt? I've never seen that, but I have seen wire nuts "fail" in the sense that they didn't hold the wires securely (i.e. the threads didn't take hold of all wires.) I've never seen a Wago fail, but then I've never seen a Wago anywhere except in my own hands

 

But the resistance of a backstab changes based on how many times and the amount of heat cycling involved. Backstabs can and have performed for years, often without issue. If they are so problematic why does the standard still allow them or why hasn't the standard and design changed? Backstabs remove the variable of correct torque applied to screw connections.

I have probably seen an equal number of melted wire nut but the information posted above says they are superior to a backstab.

 

But the resistance of a backstab changes based on how many times and the amount of heat cycling involved. Backstabs can and have performed for years, often without issue. If they are so problematic why does the standard still allow them or why hasn't the standard and design changed? Backstabs remove the variable of correct torque applied to screw connections.

I would say a good screw connection is better than a good backstab connection, but you have a good point about removing the variable from the user's hands.

As to why hasn't the standards changed, well standards do change all the time. Like if we were having this discussion in 1970 and you said "If GFCI are so good at protecting against current leaks, then why aren't they required by code?" And I'd say "I don't know, maybe someday they will be."

I don't know why the standard hasn't changed. All I can tell you is that I've taken out numerous (more than 10) backstabbed outlets that were the source of problems, or when I removed the outlet from the box the backstab mechanism just broke apart. It is probably the single most common failure I've seen in outlets, with the next ones being broken/old GFCI devices and corroded outlets in exterior settings. But you are a real electrician and I'm sure you've seen more than I have.

 

I have seen the spring as the only thing on the splice after the cap has melted off.

 

ouch

 

But if 20 times more backstabs are in use over screw connections there will be more failures even if the failure rate rate is the same. Not hard to see that more would be affected.

 

That's true. Have you actually seen fewer problems with backstabs? Based on my own experience, and what I've read on this forum, there are certainly not 20 times more backstabs, it's probably more like 50/50 or close, and I've just seen more backstab issues myself.

 

I don't have figures of one vs the other, but would guess that every production home is wired with backstabs and screws are only used on high end custom and commercial work.

 

You seem to be saying that, in your experience, the initial or long-term contact resistance of WAGOs is high.

I don't see it that way at all. No mention was made about resistance. It was that different methods can be better than others in some situations. If the Wago cannot accept larger conductors another method needs to be used.

 

If you get too fat a wire into a connection the stiffness of the wire can cause the metal to metal contact inside to become poorer or even cause a flimsy connection port to break apart. I have seen backstab connections labeled for 14 gauge wire only while the screws next to them were rated for 12 or 14 gauge.

 

Are not they all ??.......Do you remember a real short period of time when the same backstabs on a recep would take 14 AND 12.

 

Yeah, and that right there is why they continue to allow backstabs. Banning them would be too disruptive to the house construction industry.

 

Older backstabs did allow both 12 and 14. Newer ones are only for 14 gauge.

 

Here is a melted wago, or other brand. This is in a ladies locker room, individual circuit, GFCI, and the push-in connector melted.
These receptacles have a wiring harness that attaches to the receptacle via pins. The pushin connectors are part of the wiring harness and are rated
for stranded and solid wires.

The building had only been open for 1 year and 1 month at the time of replacement.

 

Were the push-ins supplied with the receptacle? If so, was the receptacle UL listed or an Amazon find?
There are so many counterfeit splice connectors out there that you gotta ask...