"Backstabbed" wiring: bad rap?

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I'm here to say that the conventional wisdom that one gets here--that "backstabbed" wiring is bad, evil, and always leads to failure--may not be correct.
[To the perplexed, "backstabbed" means that instead of using screw terminals to connect wires to devices such as outlets and switches, the stripped (solid) wire is pushed into a connector that grabs the wire inside the device. Very commonly used "in the field".]
The opinion one reads here most often is that this is an inferior wiring method that must always be suspected when there are electrical problems, that it should be avoided and that it should be corrected if found.
I'm not sure that's correct.
First of all, it is an approved, UL/CSA tested, and, most importantly, code-approved (US building code) wiring method. If it was as all-fired bad as folks here claim, why would it still be allowed? After all, the building codes tend to err on the side of caution.
My own experience, as limited as it might be, has not shown backstabbed connections to be the source of any trouble. I recently worked on a house built in the 1960s in which all devices were backstabbed. I was called to add a circuit, not to correct any problems. There was no current problem with any device that I could see, nor was there any history of any such problems.
I'd like to see some more evidence for the badness of backstabbed connections. Everything I read here is either based on anecdotal evidence, or just speculation and personal preference.
I will say that I personally don't like backstabbed connections; as tempting as they are (a lot faster than stripping/bending/screwing/crimping using screw connections), I prefer the "old-school" method. But I do think they've gotten an unfairly bad rap. Furthermore, I refrain from automatically correcting them (replacing backstabbed connections with screwed ones) when I see them, on the theory of "if it ain't broke, don't fix it", and I suggest this to others. Especially newbies and DIYers; I think it's bad advice to automatically suspect backstabbed connections as the source of a fault, and to imply that they should all be ripped out and redone.
Let the brawling commence.
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David Nebenzahl wrote:

They are allowed by the NEC because they are listed by UL.
UL used allow #12 wire in backstabs. Not anymore. Apparently their original standard was flawed. (How about the #12 backstabs in use?)
Seems like several failures come up here in this rather limited forum each year. IMHO they have minimal contact area, minimal clamping pressure, and in slightly adverse environments are subject to chemical deterioration. You will probably have no problem with backstabs. You also probably won't need the pressure relief valve on your water heater. I don't see any reason to take the chance.
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The practical point is that (in many jurisdictions) the Fire Safety Code is the only part of the Building Code that is retroactive, i.e. when the FSC is updated (some) property owners may be obligated to retrofit (some) structures or fittings so that they comply with the current code. (I do not know the American system, viz. whether part or any of the NEC is also in the Fire Safety Code. But codes are periodically revised, so code authorities may require this in future.)
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Turning a wire on a screw provides more surface area and more pressure on the connection. An installer can see how well the connection is made, unlike the blind connection of a backstab. I personally have used backstabs thousands of times without any issues. I have the experience to feel when the conductor is not fitting correctly in the blind clamp and needs to be redone. The bulk of my business is electrical repair, and a large number of open circuit problems turn out to be backstabbed outlets. I think some manufacturers make better backstab connections than others, as there have been times when I unscrew an outlet and pull it out of the box, leaving four wires, unattached in the box
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So, all the people who have had bad backstap experiences, we're all just random chance, and not evidence of a problem? Scuse me while I go barf.
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David Nebenzahl wrote:

I've seen a number of problem push-wire / back-stabbed devices personally, and they represent a sizable percentage of the number of problem devices I've dealt with.
I have a house that happily has all 20A circuits with 12ga copper wire (other than the larger dedicated circuits of course), and has many 12ga push-wire connections that are no longer allowed.
I've not had specific failures of these connections as the devices seem to be of reasonable quality, however where I have had opportunity to replace these devices for other reasons (adding GFCIs or changing to Decora style devices) I have seen evidence of less than optimum push-wire connections, i.e. discolored area at the connection point from heating.
The devices I have used for replacement have generally been the "spec grade" variety and have had the much better clamp type back-wire connections. These back-wire connections allow the same convenience of inserting the stripped wire in a hole without the need to wrap around a screw, but instead of relying on a feeble spring connection the wire is captured between full size metal plates that clamp around it with screw pressure, not a spring.
These back-wire devices also work nicely in my shop where I have stranded wire pulled through conduit. Stranded wire doesn't work well wrapped around screw terminals and not at all with the push-wire type devices.
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On 8/14/2009 6:05 PM Pete C. spake thus:

You're talking about the kind of back-wire connections found on GFCI outlets, right? To me, that's the best of both worlds: the convenience and speed of back-wiring plus the positive connection offered by a screw clamp. I think I'll start using those outlets instead of the el cheapo Home Despot ones.

Being able to use stranded wire is definitely a plus.
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On 8/14/2009 6:18 PM David Nebenzahl spake thus:

Follow-up to my own reply: Do those "spec-grade" outlets come in non-Decora style? I generally don't like Decora outlets when installing in older houses.
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David Nebenzahl wrote:

You can get "spec grade" outlets in the traditional style (I have several boxes of them waiting for upstairs renovations) but not all of them have back wire clamp type connections.
nate
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Nate Nagel wrote:

Yes, also I've yet to see a non Decora style GFCI, so for that you'd have to resort to a horribly overpriced GFCI breaker to avoid the Decora style, or else hide the Decora GFCI in a cabinet or similar and use non Decora receptacles downstream.
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On Fri, 14 Aug 2009 11:51:03 -0700, David Nebenzahl

There are some installer errors that make these more unreliable. If the wire is not straight when you poke it in you can deform the contact. If the wires are not folded in carefully you can stress the connection.
BTW the U/L listing doesn't say something will actually be reliable. It just says when it fails it won't start a fire the box can't contain.
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However, all kinds of unreliable crap is UL listed. A UL listing is a pretty good indication that something probably won't kill you or burn down your house, but says nothing at all about whether it will function properly. Building codes put a little more emphasis on function, but are also updated fairly regularly because things that were once required are finally proven to be bad ideas.
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Larry The Snake Guy wrote:

By coincidence I have the UL standard [15 years old] for "Snap Switches". For AC-only switches (which is what are commonly used) the switch must pass all the following at rated voltage: - 10,000 operations at rated current - 10,000 operations at rated current and power factor around 0.8 - 10,000 operations at rated current controlling incandescent loads [high inrush current] - 100 operations at 4.8x rated current and power factor around 0.5
IMHO this is testing for whether the switch will "function properly".
My recollection is receptacle tests are similarly rigorous and include plugging and unplugging and operating for a periods at significantly above rated current.
I think most of us would be very unhappy if fuses or circuit breakers that are UL listed did not "function properly".
For devices like TVs, it is not possible (or desirable) for UL to determine if the device is actually useful. The test is whether the device will "kill you or burn down your house".
Standards may not be perfect. They weren't for #12 backstabs, old technology #12 and #10 aluminum wire, or devices originally used with that wire. And standards for GFCIs have changed quite a bit.
IMHO standards are not adequate for #14 backstabs - maybe if they were limited to #20 wire or smaller....

The NEC has very few equipment construction requirements and I can't think of any performance requirements.
The 'prime directive' is that "equipment required or permitted by this Code shall be acceptable only if approved".
"Approved" is "acceptable to the authority having jurisdiction."
The NEC generally has only a few rather general guidelines on what should be acceptable. "Authorities" generally accept equipment that is "listed" or "labeled", but it is up to the "authorities".
The NEC did not eliminate #12 backstabs or change requirements for #12 and #10 aluminum wiring.
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bud-- wrote:

The standard you quote may or may not test whether the device will "function properly" as you did not include the pass / fail standards. If the fail standard is "fire" and the pass standard is "no fire", then the switch could well stop functioning "properly" well under the cycle count limit and still pass the test.
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Pete C. wrote:

>>

The "pass standard", _as I stated_, is that "the switch must pass all the following". The switch must still work after over 30,000 operations. And that is only part of the standard.
UL standards, as they apply to wiring components (switches, receptacles, fuses, circuit breakers, panels, wire, motor starters, wire nuts, ...), is that those products will "function properly", not just that they will fail safely.
For some other equipment, like TVs and industrial control panels, it is not practical or desirable to test if the device functions as intended, and the test is that it fails safely. That may involve using "listed" or "recognized" component parts that are tested to "function properly" as above.
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bud-- wrote:

What you stated, did not include pass criteria as *I stated*.

You say that, but you did not post the actual UL test pass criteria.

All UL tests that I'm aware of test only for safety, not durability, reliability, or functionality. If the device does not cause a hazardous condition that might result in an insurance claim (note it is *Underwriters* Laboratories, not *Consumers* Laboratories), it passes.
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Pete C. wrote:

My original post said "the switch must pass all the following at rated voltage". I quoted a portion of that in my last post. With minimal reading ability anyone should be able to determine the UL test requires a switch to survive over 30,000 operations at rated voltage and at least rated current.

With minimal reading ability anyone should be able to determine switches need to pass all of the following:
- 10,000 operations at rated current - 10,000 operations at rated current and power factor around 0.8 - 10,000 operations at rated current controlling incandescent loads [high inrush current] - 100 operations at 4.8x rated current and power factor around 0.5
That is what my original post said and the requirements were taken from the UL standard.

Then you are apparently not aware of a lot of UL tests.
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bud-- wrote:

Again, that is incomplete criteria as it does not clearly specify the pass / fail criteria. It is entirely possible for a device to be cycled that many times, with the rated voltage and current applied and fail in a way that presents no fire or shock hazard. and pass a safety test.

And again, anyone with minimal reading ability can see that what you quoted is not a complete test specification and does not include the pass / fail criteria.

I've seen a number of them and none had anything to do with non safety durability. A product could be a piece of crap and fail, as long as the failure mode did not create a hazard that could lead to an insurance claim.
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Pete C. wrote:

The pass criteria, as I have said several times, is the switch survives over 30,000 specified operations at rated voltage and at least rated current and is functional at the end of the tests. The switch is not allowed to fail during the 30,000 tests. A switch must "function properly" to survive over 30,000 operations.

What more do you want? From the information given I could construct tests for the 30,000 operations. You want the exact language from UL? Maybe you could look at your copy of UL30. The switch is not allowed to fail during the 30,000 tests. There are other additional specs, but a switch must "function properly" to survive over 30,000 operations. The test is not just about "failing safely".

THE PASS CRITERIA, AS I HAVE SAID SEVERAL TIMES ALREADY, IS THE SWITCH SURVIVES OVER 30,000 SPECIFIED OPERATIONS AT RATED VOLTAGE AND AT LEAST RATED CURRENT AND IS FUNCTIONAL AT THE END OF THE TESTS.
Did it come through that time?

As have said several times, a switch must survive all 30,000 specified operations and be functional at the end to be UL listed. A piece of crap is not likely to survive 30,000 operations and remain functional.
Or do you think a piece of crap can survive 30,000 operations and remain functional?
What UL standards have you read?
Do you really think the electrical industry would allow, for example, fuses and circuit breakers to open at random current levels, and only be required to "fail safely"? That would be ridiculous. I have not read the standard but I have seen references to required clearing times at 120% and 200% of rated current rating. They certainly are tested at their rated available fault current. I expect a lot more from fuses and circuit breakers than that they just "fail safely".
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bud-- wrote:

You really have a reading comprehension issue. Again, what you have quotes is not a complete test specification as would be used by any reputable testing laboratory as it does not contain clearly defined pass / fail criteria.
Your diversion into circuit breakers doesn't help your case at all since a circuit breakers are allowed to "soft fail" and trip at lower than their rated current.
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