Receptacles -- # of wires per screw

[RBM]

That's true, but a lot of those clamps don't work particularly well with solid conductors. Wire nuts installed correctly stay tight

[Tom Horne]

This last statement is untrue. The code requires six inches of wire in the box and extending at least three inches beyond the opening of the box "for splices or the connection of luminaires (fixtures) or devices." The code does not require that the conductors be that long after the splices are made up and the devices installed. Requiring that would overcrowd many boxes and cause more problems.

-- Tom Horne

[Tom Horne]

g on

I do not know which clamps you are referring to but that does not reconcile with my experience in thirty three years in the craft. The screw tightened clamps I have encountered have been fine on both stranded and solid conductors and work better on stranded wire then any screw binding connection without clamps ever would.

-- Tom Horne

[Tom Horne]

"110.3 Examination, Identification, Installation, and Use of Equipment. (B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling."

Information included with the listing can only be found in the Building Materials List published by the testing laboratory. To be included with the labeling the instructions must be contained within the outlined area that contains the testing laboratory seal. An Example would be "Underwriters Laboratory Listed. Copper Conductors Only." The instructions within the package that say use only manufacturers parts are not enforceable because they are not included with the Listing. The testing laboratories list items that are recognized for use with other manufacturers equipment. Thomas & Bettes makes an extensive line of circuit breakers that have been recognized for use in other manufacturers panels. Each manufacturer specifically says use only our breakers. That is not an instruction that is included in the listing or labeling and is therefore unenforceable.

-- Tom Horne

[DT]

This seems correct. I always learned that the fallback for things is the "Authority Having Jurisdiction". The NEC usually acts as the AHJ, but if something is not specified by code (NEC or local), the AHJ is usually the manufacturer. If they intended two wires to be clamped, the device would be so designed and labelled.

[RBM]

I do not know which clamps you are referring to but that does not reconcile with my experience in thirty three years in the craft. The screw tightened clamps I have encountered have been fine on both stranded and solid conductors and work better on stranded wire then any screw binding connection without clamps ever would.

-- Tom Horne

And in my thirty seven years in the business, I've found clamps work great on stranded conductors, but on some devices, such as Leviton GFCI outlets, the clamps are not nearly as secure with solid conductors

[David Nebenzahl]

On 2/11/2009 4:27 AM RBM spake thus:

I've used those same outlets and have never experienced any problems securing solid wire (#12 or #14) to the clamps. What specific problems have you had?

[pheeh.zero]

If you use back-feed and one wire on the screw-you can utilize 3 wires per screw. These are normally commercial or hospital grade 15 or

20Amp.

[RBM]

The problem is, that after tightening, the wires come loose when pushing the outlet back into the wall. They don't always come loose, but of the hundreds of these things I've installed, too many do come loose. Conversely, of the thousands of outlets I've installed with screw tight connectors, I've never had one come loose

[RonABC]

Do you have to know where it says that in the code? I'd be interested in looking that up and reading exactly what it says. Thanks.

[RonABC]

[bud--]

300.14

[RonABC]

In other words, conductors that *ARE* spliced or terminated at the box do have to comply with 300.14 even after they are spliced or terminated. Only the unspliced or un-terminated-at-the-box conductors do not have to comply.

[Tom Horne]

Ron I was not basing my position on the exception bout on the wording I quoted in my reply. Two different boards of appeal that I know of have come down in the same place. I know of no contrary formal interpretation. I'll quote the whole section so that those without ready access can follow the discussion.

"300.14 Length of Free Conductors at Outlets, Junctions, and Switch Points. At least 150 mm (6 in.) of free conductor, measured from the point in the box where it emerges from its raceway or cable sheath, shall be left at each outlet, junction, and switch point for splices or the connection of luminaires (fixtures) or devices. Where the opening to an outlet, junction, or switch point is less than 200 mm (8 in.) in any dimension, each conductor shall be long enough to extend at least

75 mm (3 in.) outside the opening.

Exception: Conductors that are not spliced or terminated at the outlet, junction, or switch point shall not be required to comply with

300.14."

My position, and the position of the Virginia state board of permit appeals, is that the six inches of free conductors is required in order to have enough wire to make the splices and connections during make up and not forever afterward.

-- Tom Horne

[RBM]

Ron I was not basing my position on the exception bout on the wording I quoted in my reply. Two different boards of appeal that I know of have come down in the same place. I know of no contrary formal interpretation. I'll quote the whole section so that those without ready access can follow the discussion.

"300.14 Length of Free Conductors at Outlets, Junctions, and Switch Points. At least 150 mm (6 in.) of free conductor, measured from the point in the box where it emerges from its raceway or cable sheath, shall be left at each outlet, junction, and switch point for splices or the connection of luminaires (fixtures) or devices. Where the opening to an outlet, junction, or switch point is less than 200 mm (8 in.) in any dimension, each conductor shall be long enough to extend at least

75 mm (3 in.) outside the opening.

Exception: Conductors that are not spliced or terminated at the outlet, junction, or switch point shall not be required to comply with

300.14."

My position, and the position of the Virginia state board of permit appeals, is that the six inches of free conductors is required in order to have enough wire to make the splices and connections during make up and not forever afterward.

-- Tom Horne

That's all fine and well, but it would really be helpful if in the future, you preface your replies to indicate that you're quoting some particular entities interpretation of the NEC

[terry]

I read that as 'Twist bare ground wires together place the twisted section under screw of the metal box and then use one of the wires to connect to the duplex'.

Unless the outlet is being 'split' (For say an Edison circuit or to switch one of the hots of the outlet) there is provision on a typical duplex to terminate two white neutrals and two black live wires. Other than that pigtail them. And yes I prefer a good quality duplex that has those terminals that trap the stripped wire end under a metal plate as screw is tightened down.

[RBM]

And furthermore, what business does the state of Virginia, or any other state, have to interpret National Electric Code? They have the right to use it, or not, they can make their own code if they choose, but the NFPA, the people who write the NEC, have panels of their own, who you can write to, to have any section of code interpreted. How arrogant that would be for someone to believe that they can interpret something better than it's author.

[David Combs]

Hi! What's a "back feed type outlet"?

Thanks!

David

[David Combs]

Are you saying that when you need to connect two wires to a screw, what you do is pigtail THREE wires together, and then that third wire, the new, short one, and hook THAT one to the screw?

Thanks,

David

[Steve Barker]

Exactly, you got it. and if the box happens to serve two directions then you have four in the nut counting the pigtail.

steve