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Help with Wire 'Looping' inside a box

Posted by scottys (My Page) on
Mon, May 31, 10 at 21:51

I decided to rip down the sheetrock in my hallway rather than try to strip off 3 layers of wallpaper and as long as the walls are open I thought I'd change the old #14 cloth covered wire BX cables with new #12 BX (it's a 15 amp circuit).

The problem is this: There is a 2 toggle switch box and one of the black wires has the insulation removed in the middle of the wire so it can loop around the screw and continue over to a screw on the next toggle switch to give that circuit power. The #14 wire is thinner so it was easily bent but the #12 is thicker and harder to bend and also I'm not sure how you can easily remove the plastic insulation mid-stream like it was done previously.
Anyone have ideas? Thanks.


Follow-Up Postings:

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RE: Help with Wire 'Looping' inside a box

Two pigtails on the power wire with a wire nut, one for each switch.


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RE: Help with Wire 'Looping' inside a box

No reason to use #12 wire on a 15 amp circuit. It just makes it harder to work with and will affect box fill calculations.


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RE: Help with Wire 'Looping' inside a box

The method you describe of chaining the power leads to multiple switches, or receptacles for that matter, used to be standard practice. It is no longer accepted.


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RE: Help with Wire 'Looping' inside a box

"It is no longer accepted.

By who?

It is not in violation of the NEC.


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RE: Help with Wire 'Looping' inside a box

also I'm not sure how you can easily remove the plastic insulation mid-stream like it was done previously.

You don't remove a section. Just use your handy electrician tool to cut the insulation and then slide it out for the amount of exposure you desire. Repeat for multiple fixtures.


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RE: Help with Wire 'Looping' inside a box

Thanks for all of your responses.
Hendricus: used the pigtail/wirenut idea and it worked nicely, much easier than the loop method with the thicker #12 wire.
Joed: You are correct, #14 would have been fine, but I prefer #12.
Randy427: I believe Brick is correct- this method while not commonly used, is not a violation of NEC.


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RE: Help with Wire 'Looping' inside a box

"It is no longer accepted.
By who?

It is not in violation of the NEC.:

Yes it is.

The NEC requires that all devices be installed according to their listing instructions.

The side wiring instructions for switch and receptacle devices do not list 'looping' of conductors as described above as an accepted wiring practice.

Rather, instructions typcially show conductors prepared with cut ends only, the insulation stripped from these cut ends to a prescibed length, and then only looped a maximum of 3/4 of the way around a terminal.

Installating side wired conductors any other way is a violation of the device listing and therefore a violation of the NEC.


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RE: Help with Wire 'Looping' inside a box

"The NEC requires that all devices be installed according to their listing instructions.

The side wiring instructions for switch and receptacle devices do not list 'looping' of conductors as described above as an accepted wiring practice."

The listing instructions only include the length of stripped wire and that it must be under the screw-head in the correct direction.

They say nothing about were the wire can then go.

It is in conformance with the NEC and the device instructions as long as the length is at least the same as the strip gauge length for the device.

It actually works well in multi-gang switch boxes.

The switches can be wired together ahead of time, and then a single wire nut used to feed them all power.

Is is a little more work to replace a device, but avoids pig-tails all over the place and a crowded box.


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RE: Help with Wire 'Looping' inside a box

Sorry, I do not agree with your interpretation brickeye.

All wiring instructions and listing for receptacles illustrate cut conductor ends with specific instructions to remove the insulation the fixed distance depending on whether the conductor will be side wired or back wired.

The UL listing of receptacles only permits connections to the side terminals or back terminals as tested according to the devices wiring instructions.

Unless you can prove otherwise with specific listing instructions from a specific manufacturer or supporting documentation from the UL White Book or some other testing aganecy to back your claim, using this looping-through method while side wiring remains a violation of the NEC at worst.... and a very sloppy, shoddy wiring practice at best.


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RE: Help with Wire 'Looping' inside a box

> and a very sloppy, shoddy wir ing practice at best.

I would have to respectfully disagree here.

For me, anyway, it's easier and faster to use a wirenut and multiple pigtails. However, I agree with Brick that the loop method is a significantly less cluttered one. I also suspect it's more secure and thus actually a bit safer than a wirenut splice.

As for the code, I can see both sides of this discussion. To my recollection, though, no device *ever* specified looping in its instructions. Despite that, it was a fairly common method 30-40 years ago. What's changed? I'd venture to guess that it's a labor issue rather than a code issue. It's probably faster for most pros to make up the pigtails than to fiddle with the TP insuulation, but I could be wrong.

This is one that you'd probably want to run by your own AHJ. Since there's tradition behind this method, maybe the older ones would be more open-minded about it.


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RE: Help with Wire 'Looping' inside a box

"As for the code, I can see both sides of this discussion. To my recollection, though, no device *ever* specified looping in its instructions. Despite that, it was a fairly common method 30-40 years ago. What's changed?"

Just because guys have been "doing it that way for 30-40 years" does not make the practice right or even code compliant.

It isn't.

They don't call them "terminals" for no reason, you know.

They are called "terminals" because that is where conductors are meant to terminate and end....not "pass through".
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For the record, I am an AHJ and an electrical inspector.

For existing work that had no other practical alternative but to continue to use a looped conductor, I'd permit it.

For use in new work, I'd reject it everytime.

Because if you plan properly, there is never, ever any reason to use that wiring method. Ever.

But I'm sure there will be some older (and younger) ones who would disagree.


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RE: Help with Wire 'Looping' inside a box

But I'm sure there will be some older (and younger) ones who would disagree

At least you got that part right :)


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RE: Help with Wire 'Looping' inside a box

"The UL listing of receptacles only permits connections to the side terminals or back terminals as tested according to the devices wiring instructions."

And that is exactly how they are being used.

I have never had any AHJ anywhere complain about window joints to attach multiple devices to a single wire, and it is not prohibited by the NEC or any installation instructions.

As far ads the device screw goes what happens to the wire after it leaves the device terminal has nothing to do with the device.

It is slower and more labor intensive to create window connections so it is not seen as commonly as it used to be.

The quest for faster installation has already resulted in push wiring on devices for both #14 and #12.

The failures in #12 connections quickly led to them not being allowed, and the holes for push wiring no longer accept #12 conductors.


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RE: Help with Wire 'Looping' inside a box

Every Military and commercial specification I've ever installed
required this style of wrap to prevent strain on the connection
and possible arcing or loosening. Omega shaped bends place
reverse strain on the connections. Ω

"wrap the wire 2/3 to 3/4 of the distance
around the screw without overlapping "

Here is a link that might be useful: Fig. 2.


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RE: Help with Wire 'Looping' inside a box

And yet the installation instructions provided in figure 2 do not illustrate nor approve 'omega' type connections, so go figure that interpretation...

I have never seen any devices that permitted this 'omega' wiring method, particularly in residential work.


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RE: Help with Wire 'Looping' inside a box

man-42 makes a compelling case... but I was wondering about the effect on box fill calcs for each method...

... when I found this from THE Authori-tah, Mike Holt, official High Priest of NEC 2008... it shows that not only can you use the "looping"/Omega technique withIN the box, but that the legally mid-stripped conductor may continue on to another j-box, ad infinitum.

Considering there's no hard limit on the number of switches and receps one can connect to a single 15A branch, SURELY someone on this forum holds the record for the most mid-point Omega strips on a single conductor. ;')

Here is a link that might be useful: Loops OK, but watch the LENGTH w.r.t. box-fill


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RE: Help with Wire 'Looping' inside a box

And yet the installation instructions provided in figure 2 do not illustrate nor approve 'omega' type connections, so go figure that interpretation...

There are three disapproved methods and the 'omega' is not on them either. So...still figuring.


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RE: Help with Wire 'Looping' inside a box

'Window' splicing and terminal connections have been used (and even preferred) in high reliability wiring for a very long time (and remain common in ships, aircraft, and spacecraft (luckily the NEC does not apply to much of these).

By reducing the number of separate connections reliability is improved.

Manhatten42 is blowing smoke.

This would fall within workmanship, and unless NOT allowed specifically it IS allowed.

It likely originated when all joints were soldered, and saved an enormous amount of work (and space) in boxes.

While we throw wire nuts (and other approved connections around) EVERY joint was soldered for many years, making a 'window attachment' to a terminal both safe, effective, and a real tie saver.


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RE: Help with Wire 'Looping' inside a box

Wow, didn't expect to still see discussion on my original question.

Manhatten42: You stated your opinion that the loop method is a sloppy and shoddy wiring practice. I just wanted to note that my home was one of 60 or so built in a 3 block radius in 1952-1953 and presumably all wired the same since it was just one builder.
57 years later they are all still standing so the loop method can't be so bad regardless of what the NEC currently may or may not think about the method.


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