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Why not 2 grounding screws on receptacles?

Posted By: chimo

Why not 2 grounding screws on receptacles? - 10/14/04 12:56 PM

All-

If you are wiring a series of outlets, and are allowed to use one set of screws for the line, and one set for the load, why do you have to pigtail the ground? I understand the ground screw is only rated for 1 conductor, so why don’t they make outlets with 2 ground screws? Wouldn’t this make for a safer connection (eliminating a possible weak connection with a wire nut?)

Thanks,

Chimo
Posted By: Creighton

Re: Why not 2 grounding screws on receptacles? - 10/14/04 02:47 PM

See 250.148. The continuity of the grounding conductors shall not be interrupted. First ground the box, then ground the receptacle to the box, so that removal of the receptacle willlnot interupt the grounding circuit.
Creighton.
Posted By: Anonymous

Re: Why not 2 grounding screws on receptacles? - 10/14/04 05:52 PM

If you are talking about a duplex receptacle you might think about it this way. Your wiring two individual receptacles and have the option to break the tabs to either half switch or wire with two different hots. Or, to break off both tabs and wire with two individual circuits / neutrals. either way your only grounding one strap or yoke.
Posted By: earlydean

Re: Why not 2 grounding screws on receptacles? - 10/14/04 06:07 PM

Grounding is so important that it cannot depend upon the device for it's continuity. Like Creighton said, first the continuity of the ground is assured, then you bond the receptacle to the grounding system via pigtails or jumpers. By the way, a wire nut is a superior connection, in my opinion. Although either, done correctly, is an excellent connection.
Posted By: chimo

Re: Why not 2 grounding screws on receptacles? - 10/14/04 06:38 PM

Now I understand, continuity is the key. Which brings up one more question- In a duplex config., why only allow 1 conductor under the ground? If the grounds were twisted together, you would maintain continuity if the outlet was removed. Is it just a matter of solid contact between the wires & screw?
Posted By: Tom

Re: Why not 2 grounding screws on receptacles? - 10/14/04 10:15 PM

The basic rule is one wire per terminal, so that limits you to one wire under the screw. This rule applies to all terminals, not just equipment grounds.

Twisting the wires together is not recognized as a splicing method, you have to finish the job with a splicing device (such as a wire nut) or brazing, welding or soldering.
Posted By: golf junkie

Re: Why not 2 grounding screws on receptacles? - 10/14/04 10:32 PM

We pigtail all conductors, I thought that everyone did. It is not considered code compliant to run the full ckt. current through a device strap.

I don't know the code reference off the top of my head but that's the enterpretation here in Nebraska.

GJ
Posted By: resqcapt19

Re: Why not 2 grounding screws on receptacles? - 10/14/04 11:04 PM

GJ,
Quote
It is not considered code compliant to run the full ckt. current through a device strap.

That will be news to UL as the listing says that you are permitted to use the device to splice the circuit conductors.
Don
Posted By: e57

Re: Why not 2 grounding screws on receptacles? - 10/15/04 12:04 AM

I too splice all conductors, UL listed or not. Personnal quality / prefferance. (Not saying that those who do use the device terminals perform lesser quality work.) But I would have a kiniption if one of my guys does it, as I feel it sooner or later may become a call back for warrantee. And, I would defininatley hit the roof if it were done on a 3, or 4 wire circuit. This could subject the circuit to under/over voltage should the neutral fail. And, that may also be a code requirement for the 'grounded conductor', as well as the 'grounding conductor'. (I'm on my other computer and can't check now.)
Posted By: electricman2

Re: Why not 2 grounding screws on receptacles? - 10/15/04 01:31 AM

Pigtail is required for the grounded conductor if part of a multiwire circuit.
Posted By: twh

Re: Why not 2 grounding screws on receptacles? - 10/15/04 01:46 AM

They do, or did, make a receptacle with two ground screws. It stands out in my mind because there were two ground wires wrapped around each screw. There were also two neutrals and two hots under each of the other screws. 12 wires on a receptacle. When you have that many 12 awg wires in a 2.5 inch deep device box, there just isn't room for marrettes.
Posted By: CRW

Re: Why not 2 grounding screws on receptacles? - 10/16/04 02:41 AM

e57--Correct me if I'm wrong--are you in the Chicago area? It has always been code there to pigtail the neutral(grounded conductor) even in 2 wire circuits for the same reason as the NEC requires it for multi-wire. Since I started in Chicago, we always pigtailed every wire (well, actually we sometimes stripped a solid conductor midway and looped around the screw instead of pigtailing), and I never spliced on the device until I moved to another part of the country, and only then under the foreman's orders because they considered it faster. Plus, in Chicago we never pulled ground wires in a pipe, so there was no (wire)ground to the box or receptacle. In fact you couldn't even buy green screws at the supply house, they never saw them before.
Posted By: MattE

Re: Why not 2 grounding screws on receptacles? - 10/16/04 04:48 AM

I've seen some older GE Spec. grade receptacles with 2 ground screws, but only one of the ground screws was used in the installation where I saw them.
Posted By: e57

Re: Why not 2 grounding screws on receptacles? - 10/16/04 06:35 AM

No CRW, I'm in beutiful (sunny? What-ever, we sometimes never see the light of day here!) San Francisco, California.

On the pig-tailing, I just do not think that devises should carry the circuit, 2-wire of otherwise.

So whats this now, they dont have green screws in Chicago? They do ground devices there, right, what do they use clips?
Posted By: electure

Re: Why not 2 grounding screws on receptacles? - 10/16/04 11:25 AM

A little confusion for me. [Linked Image]..nothing new.

Is a 15 amp receptacle rated for the feed-through of a 20 amp circuit??
My belief has been that a 15A circuit could be fed through the device, but not a 20A.

Not important in my world...I pigtail them regardless...S
Posted By: CharlieE

Re: Why not 2 grounding screws on receptacles? - 10/16/04 12:45 PM

UL and other NRTLs do test the feed through strap for 20 amperes continuous on a 15-ampere receptacle. [Linked Image]

- - - - - - - - - - - - - - - - - - - - - - - - - - -
Charlie Eldridge, Indianapolis, Utility Power Guy
Posted By: Active 1

Re: Why not 2 grounding screws on receptacles? - 10/17/04 04:54 PM

I got green 10/32 screws in chi land. The receptacles here should be the self grounding type that has the clip on the 6/32. You could also use a ground wire instead but that would be rare.

GFIs here should have a equipment ground pig tail because they don't come with the self grounding clips on the 6/32. I like those premade pigtales with the screws. A few jobs might be speced out as a equipment ground wire in every pipe. Switches never have a ground to them here.

Lots of places here prohibit using a device to splce conductors feeding the next thing.

Tom

Tom
Posted By: Trumpy

Re: Why not 2 grounding screws on receptacles? - 10/17/04 05:25 PM

Forgive me for being a little out of touch from being overseas, but could I please ask why the Tunnel type terminal isn't used on electrical equipment in the US?.
[Linked Image]
Posted By: iwire

Re: Why not 2 grounding screws on receptacles? - 10/17/04 05:49 PM

What the heck is a tunnel terminal? [Linked Image]
Posted By: Trumpy

Re: Why not 2 grounding screws on receptacles? - 10/17/04 07:36 PM

Bob (iwire),
Here's a picture of a switch that uses Tunnel terminals.

[Linked Image]

The terminals for sockets here are a lot larger.
Posted By: bp-redbear

Re: Why not 2 grounding screws on receptacles? - 10/25/04 02:21 AM

What about a GFCI receptacle that is used to protect other receptacles downstream of it?

Seems likee I recall reading that GFCI's don't work f pig-tailed.

What if a GFCI is used in a multi-wire circuit?
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