"Backstabbed" wiring: bad rap?

[David Nebenzahl]

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.

[bud--]

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.

[albee]

Solely anecdotal, but seems like quite a coincidence that I've had problems with them staying connected, particularly in receptacles that received frequent use (not taking out and working on, simply plugging and unplugging of appliances). As a previous respondent said, if done correctly and not disturbed... But if "anecdotally", merely using the receptacle a lot in the manner intended is enough to cause such disturbance, well, then it's not functioning as intended.

Now, I don't have non-backstabbed ones with which to compare them, but I can't fathom that a non-backstabbed receptacle would have done the same.

My amateur and anecdotal .02 worth.

[RBM]

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

[Stormin Mormon]

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.

[Stormin Mormon]

I've seen several problems with backstab sockets, but few or none with wrap around the screw types.

[Don Phillipson]

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.)

[Pete C.]

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.

[David Nebenzahl]

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.

[David Nebenzahl]

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.

[Nate Nagel]

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

[Pete C.]

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.

[gfretwell]

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.

[Larry The Snake Guy]

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.

[Robert Green]

I've had two backstab failures, one near a disposal where the switch was mounted on an outside wall and another on an inside wallswitch. I think the thermal expansion/contraction plus the disposal vibration did the first one in. Not sure why the second one failed. It's an indisputable fact, though, that there's much more connection area in a screwed down wire than there is with a pinch and grab kind of connector.

If the grabber is hard enough to bite into the copper to make a connection, it's most likely strong enough to bite through it *eventually* if helped by vibration, thermal forces and even the simple repeated toggling of the connected switch. Once arcing starts, no matter how small, corrosion and failure are likely to follow. More connection area in the screw connections means less of a chance of arcing or pulling loose. Also, it's very much harder to see a bad back stab than it is to see a wire not completely under a screw. I'd agree that the delisted AWG 12 is a strong hint that anecdotal evidence has added up to backstabbing being a bad idea, both with people and electrical devices.

BW

[Doug Miller]

Note that it is no longer approved for anything except AWG 14 conductors. Code once permitted the use of AWG 12 conductors in backstabbed connections, as it once permitted aluminum conductors in branch circuits and various other practices and materials that have proven in experience to be less safe than originally believed.

If installed properly _and not disturbed_ it's unlikely they'll have much problem. OTOH, if a backstabbed receptacle or switch is removed for any reason, simply the act of moving the device can loosen the connections enough to cause trouble.

I'd consider the de-listing of AWG 12 conductors to be sufficient evidence.

[Perry Aynum]

Why take the risk? Is the extra two minutes required to pig-tail the ends and screw them down too much?

[JIMMIE]

Obviously you have never paid $300 for an electrician to find a bad one or have the power in you livingroom go out when you have guest coming over because of one. As far as I am concerned these things were BROKE the day they were made. After my experience and expense with them I made the decision to replace all the outlets and switches in my home. When I started performing the replacements many of the wires pulled out of the back of the switches and outlets when I was pulling them out of the box. Most of the wires only required a firm tug to pull them from the device and only a few actually required me to press the release.

[RBM]

Obviously you have never paid $300 for an electrician to find a bad one or have the power in you livingroom go out when you have guest coming over because of one. As far as I am concerned these things were BROKE the day they were made. After my experience and expense with them I made the decision to replace all the outlets and switches in my home. When I started performing the replacements many of the wires pulled out of the back of the switches and outlets when I was pulling them out of the box. Most of the wires only required a firm tug to pull them from the device and only a few actually required me to press the release.

Out of curiosity, do you know who the manufacturer was?

[Andrew M. Saucci, Jr.]

One advantage of a backstabbed connection is that if the end of the conductor is carefully trimmed, none of the conductor is actually exposed inside the box. That can reduce the chance of a short, especially in a metal box or where a bare grounding conductor is present. This would be a particular advantage if screw terminals were not present at all (uncommon these days).

Screw terminals can be dangerous too if they are over tightened or under tightened, or if the conductor is poorly trimmed.