As a homeowner, I have done many wiring projects over the years and I have always felt that screw connections were better and safer that the “quick wire” push in type. I have never felt that they offer a solid bond as does a screw connection. They are obviously legal or they wouldn’t be there. Am I being overly nervous about this?
Listeners write in about removing masonry chimneys and ask about blocked ridge vents, deal-breakers with fixer-uppers, and flashing ledgers that are spaced from the wall.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
No, nobody who's seen a lot of electrical work likes the cheap back-stab ones. They're legal, but they fail a lot.
There are ones where you stick a wire straight in the back, and the screw tightens a clamp on it, which are about as good as the traditional wire wrapped around the screw. But you're right to avoid the spring-action back stabs.
-- J.S.
Hi Bob,
Don't worry..be happy! I've owned my own electrical contracting company for 27 years now and it's o.k. by UL as well as many professionals. Ideal has a wire connector that replaces the common wire nut that's a push in and it takes 4#12 conductors. It works great and it sure makes life simple. I might add that I've seen as many problems with loose screws on devices.
Delbert
I agree with Delbert!. But we only use them when we need to due to many wires in box etc. Those new stab in connectors are way cool. Also we have been using some higher end recessed cans that come with them already attached!
My first task many years ago working as an apprentice was hotchecking new homes in a very large subdivision. Hotchecking consisted mostly of testing every device in a new house to make sure it worked and had the proper polarity and ground and fixing those that didn't. Almost EVERY brand new house would have 3 or more circuit segments that were just plain dead because of loose backwire spring connections. I'm embarrassed to say what the approved method of fixing them was, but it did not involve any tools.
I NEVER backwire anything. The best thing you can do is splice all of the wires in each box of each polarity to a single pigtail and wire that to the receptacle. Its fairly easy to make a good wirenut connection (twist the wires with pliers then put the wirenut on as tight as you can get it with your hand). Then fasten that wire to the receptacle tightly. This way a loose screw would only affect the load connected to that single receptacle.
Dave
Thank you for taking the time to respond. I don't know how these things got approved but I have always looked at them suspiciously. I'll have to go back and all the new wireing but the peace of mind will be worth it. Thanks again, Bob
Seems to me that there have been more positive responses for "back stabbing" with little recommendation to go back and rewire. Did you just want some (very little) justification before you posted your question? Tyr
I appreciate your input. What prompted me to post my question was this; the relative quality and safety of the two types of connections. I know that tight is good when it comes to electrical connections. The wire "backstabbed" into a switch or outlet can easily rotate. Having taken one apart, I am a bit concerned about the contact surface area. I know that a good and tight screw connection has a lot of surface contact. Push in connections must be generally safe or they wouldn't be allowed, but aluminum wire was once considered OK for resedential use but after numerous fires traced to its use, it is no longer used. Now, I may be incorrect about aluminum wire as I'm not in the business, and I certainly don't want to start a new issue, but sometimes good ideas don't work out. The amount of knowledge and expierence on this forum is overwhelming and I thank each and every one of you for taking the time to set me straight.
Hi Bob,
Just a quick note to let you know that aluminum wire is used every day. That old rumor started in the early 1970's when there were several fires blamed on aluminum wiring in mobile homes. The real problem was not with the wire, but with terminating the wire under receptacle screws that were copper or brass. The properties of the two types of metal were not the same, thus we had expansion at different rates which caused the connection to become loose over time. Once the process started it kept going. Loose connections caused overheating/arcing at the termination point. In some cases a fire resulted. There are receptacles that are UL listed for use with copper or aluminum wire. Most all wire connectors, split bolts, and terminal blocks come rated for AL/CU applications.
Delbert
Thank you for the clairification on aluminum wire. I really don't want to rekindle that issue. It was merely used as an example. Thanks again.
I don't like it but my house has aluminum wire and it is not a trailer, mobile home or manufactured home (take your pick--all the same thing). When I built an addition on my own home (if I was a cobbler I would fix my own kids shoes--not) I needed the power company to move the wire coming from the pole to the new service location--guess what? Aluminum. I always watch out for switchs/outlets that are rated for aluminum. There probably is a different rate of expansion between aluminum and copper. I always believed that the problem was more due to oxidation of aluminum/copper connections and thus a deteriorating contact. There is also a problem when copper lines are connected to the old galvanized water pipe. Galvanic response between the two metal will cause the joint to fail.
Even though I'm personally stuck with aluminum I don't think much of it. Cu is stronger and may work harden but doesn't just break like aluminum. As far as I know (I'm a general contractor and only hire electricians) aluminum is not code anywhere in residential use any more). The quick connects are not a new idea and are here to stay. If you feel better using the screws in your house--go for the feelings. I just don't think its really going to make much difference to anything else. Let's see--the black wire goes on the gold screw..........Tyr
The main problem with Al wiring is that the oxide is a very good insulator. Copper oxide isn't nearly as good an insulator. Once a joint starts getting warm, oxidation increases 10-fold, and that further reduces the contact area, contributing to a "runaway" situation.Differences in thermal expansion further contribute to the problem.AFAIK, it was never legal to terminate Al under a standard fixture screw -- the back-stab connection was always supposed to be used, since it had a knife-edge contact that supposedly would exclude oxygen and prevent oxidation. Worked in theory, not in practice.
I'm pretty sure aluminum is still code approved for service entrance cable (SEC) and to supply sub-panels. Personally, I specify copper for that too, as I don't see any reason to mix metals, but as far as I know, code allows it.
The advantage of aluminum is that it's much cheaper than copper. The disadvantage is that it requires special anti-oxidant compound and proper care to produce a safe installation.
For big feeders, the material savings justify the extra installation expense. For branch circuits, you have a lot less material and a lot more ends, so the economics don't justify it. I don't even know if they still make #12 or #14 in aluminum.
Code must allow it for feeders, because it's done a lot. There are guys here who can quote code chapter and verse, maybe one of them can tell us if there's some gauge below which it's not allowed.
-- J.S.
In my 1999 NEC, the main conductor ampacity rating table is 310-16. It lists ampacities for Al conductors all the way down to 12 AWG, but not for 14 AWG.
You basically have to use a size larger with Al, so #12 Al is equivalent to #14 copper. And of course #14 copper is the smallest allowed in standard wiring (outside of fixtures).
Aluminum is cheaper than copper, but I'm not sure I would go so far as to say much cheaper, unless you are a developer doing an entire subdivision. Several years ago when I did a main panel upgrade, I think the difference on the SEC was about $35.But aluminum does bend a little easier too, I think, if you have to get around a bunch of corners.
back in the 60's / 70's when copper became dog expensive general aluminium house wiring became popular...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Yeah, there was a copper "shortage" (did Enron exist back then?) around 1965. Some utilities were even using steel wire for service entrances, etc.
I should have been more clear. I know Al is used in feeder lines and therefore must be code. I am unaware of any code allowing use of Al for general residential wiring. I really wouldn't change my specs if it were. Got some informative discussion going with my unclear message though! Tyr