Screw type back wired devices
JohnSprung
| Posted in Energy, Heating & Insulation on
I used to think that these were almost as good as the traditional kind where you wrap the wire around the screw. But recently I had a couple where the screws had loosened for some reason, and the wires fell out the back.
So, now I’m wrapping the wires around the screws again. A real pain on the kind where the screws are flopping around.
— J.S.
Replies
Aren't GFCIs similar to the type you describe? Push in wire, tighten screw and internal clamp traps wire. Sound familiar? And you've had problems with them?
"I am the master of my fate, I am the captain of my soul." Invictus, by Henley.
Yup, it was on GFCI receptacles in two different locations. I took out the mounting screws, pulled the receptacles out of their boxes, and a wire or two fell out the back (Bathroom, hot and neutral, back deck hot only). Given the construction date of the house and the time we've had it, they had been there at least a year and a half, but less than 16 years. Perhaps they were OK when installed, but thermal cycles or vibration worked the screws loose?
One of my little projects is to go thru all the boxes in the whole place, checking things out and replacing the ultra-cheapo devices.
-- J.S.
John,
Did the same thing in my house some years ago as part of the prep work to construction of an addition and electrical service upgrade. Worthwhile project that can be done in stages.
Make yourself a list as you go as to what breaker controls what in the house. Saves lots of time in the future when you want to add on, have a problem or whatever. I organized results by room into a directory of sorts. Also marked CB numbers on the back of each cover plate for a quick reference for myself / future owners.
Beware this may be a "project maker" project. I discovered that all 3 bathroom outlets, 2 outside outlets, and 2 kitchen outlets were all on the same GFCI breaker. This situation required further attention.
Jim
Never underestimate the value of a sharp pencil or good light.
> Make yourself a list as you go as to what breaker controls what in the house.
Yup. Also I'm writing the breaker numbers with a sharpie inside the boxes.
-- J.S.
Sounds like operator error....
:)
Mr. T.
Maybe Christmas doesn't come from a store...
Maybe Christmas means a little bit more...
Wrapping the wires around most GFI terminals is a real PITA. Those screws are often recessed and between the loose screw slapping around and the angles all wrong it is harder than it need be. And as pointed out by one inspector it may also violate the manufacturers instructions for installation. Itself a violation of the Code. Sometimes you can't win for losing.
Most common reason for the clamping-type terminals failing, in my limited experience, is that the screws come backed out and the installer fails to shake the plates down so the conductor goes under them. Done it a few times myself. Interesting enough the tightening of the plate without a wire under it may, in some cases, distort the casing on the opposite side and make the wire feel attached.
The screw gets tight and the wire firms up and sticks straight out of the hole. Easy, especially in a rush or otherwise distracted, to miss that the wire is really not firmly connected.
Another point of failure is that the screw just isn't tightened enough. A wrapped screw has the advantage of being both easily visible and mechanically linked in that the wire hooks on the screw threads. The clamping device seen on GFIs are, seems to me, much more dependent on tightening pressure because the wire is straight and any slight looseness allows the wire to pull or be spun out.
My favorite plan is to pull firmly on each wire to make sure it is rooted firmly and to, just before the device is screwed into the box, double check the screws for tightness. In my experience I have to do both because a tight screw means little if the wire is on the wrong side of the plate and a wire on the right side of the plate does little good if the screw isn't tight enough or the conductor's material has migrated enough to loosen the joint.
I tell my help to 'tug and twist'. Sometimes they even do.
Had probs like that too while replacing outlets (46 total). Turns out the biggest cause (for me) was the wire being a little "bent" or "curved". You push the wire in, tighten the screw, then proceed to twist and bend the wires into the box so as to anchor the outlet. The bent wires "twist" under the clamps, and as a result come loose.
After the first instance, could not sleep well so.........
Went back two weeks later, removed each one (yup, all 46) and pulled on the wires. Had a total of 5 oulets w/ loose wires if memory is correct.
Now I "twist and tug" before I install.
I wonder if a little LocTite on the screws might help? That of course assumes that everything is positioned correctly, but if the screws are working loose from electron motion, maybe "glueing" them down would be a good idea?
Maybe a light grade of loctite, or the old substitute, fingernail polish.
-- J.S.
No way the screws could work loose. I think the failure cases are due to either getting the wire on the wrong side of the plate or failing to tighten sufficiently (enough to deform the wire slightly) in the first place.
If ignorance is bliss why aren't more people
happy?
Tightening them too tight can also be a problem, where you strip the threads in the plate. it'll never be possible to keep it tight after that.
Yeah, but you'll generally realize when you've done that, and can then correct for it by replacing the outlet or moving the wire to the other screw. And it would be just as easy to strip the screw doing normal side wiring.
If ignorance is bliss why aren't more people
happy?