Grounding question when replacing pullchain fixture

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Old 09-27-08, 11:22 AM
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Grounding question when replacing pullchain fixture

Rough 'schematic' can be viewed at www.spunsimply.com/wiring.gif Hopefully it illustrates the below.

Previous owner of the house had installed a pullchain light fixture in a closet in the middle of a run of cable coming from the panel and going to several other loads (2 outlets and a switched light fixture) in another room. This was an old fixture and it finally burnt out some time ago (before I moved in). The cable is new - three wire, modern insulation, etc. [section 1 on diagram]

The old fixture was not grounded. As far as I can tell, the owner cut the three wires in the cable, attached 'both' hots to the hot screw on the fixture, both neutrals to the neutral screw, and then put a short length of bare copper wire on as a pigtail connecting the two ground wires to each other and to a screw that was sunk into the closet ceiling (within a box, just not a box with a ground screw) - the ground wire did not connect to the fixture itself. This created a parallel circuit so even when the fixture blew, the outlets and light beyond continued to work. [section 2]

The replacement fixture has a single hot, a single neutral, and a single ground coming off of it, as you'd expect. My plan was to simply connect the three strands of each type of wire - one from the fixture, two from the two halves of the split cable. [section 3]

Here's the question - and a point of disagreement with my friend who was looking at this with me - assuming the panel is properly grounded, then making the connections this way should a) work without any dangers, b) retain the parallel circuit so everything function independently and c) be an improvement over the old setup, no? The fixture will now be properly grounded to the panel/outside as opposed to being grounded just to the house. Grounding anything to the box or a stud will keep people from getting zapped but is a lesser fix than this method, right?

If I've missed anything blunderously obvious as well, please let me know. Thanks!
 
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Old 09-27-08, 12:32 PM
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Depending on the size of your closet and the type of fixture you may not be able to install any lighting.

Incandescent surface mounted light require 12" clearance past the shelf edge. Fluorescent can be reduced to 6".

If you can descirbe your closet setup more can be determined if you can do what you want.
 
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Old 09-27-08, 01:56 PM
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It's close to a walk-in closet size with plenty of distance between the shelf edge and the point on the ceiling where the fixture is hung. An electrician I trust looked at the space a while back and his one note was that I would need a covered fixture - no bare bulbs - because it's within a living space. Based on that I bought a standard flushmount ceiling fixturem the kind with the square of frosted glass.
 
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Old 09-27-08, 09:54 PM
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Connecting a circuit grounding wire to the grounding connection on a fixture is always the right thing to do.

Connecting two wires to one screw is always the wrong thing to do.

Other than the grounding and the two wires under one screw, there is no difference between the old and new diagrams.

The fixture will now be properly grounded to the panel/outside as opposed to being grounded just to the house. Grounding anything to the box or a stud will keep people from getting zapped but is a lesser fix than this method, right?
THe above makes absolutely no sense to me. The phrase "grounded just to the house" is not clear. There's only one place that a circuit can be safely grounded--there must be a path for any fault current to flow all the way back to the power company transformer.
 
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Old 09-29-08, 10:32 PM
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I don't know why I typed house - I meant box. This was the disagreement with a friend - is the pigtail still needed when the new fixture has a ground wire (and was it doing anything in the old setup)? The options would appear to be attach the fixture ground wire to the cable ground (tied back together), or do that and also run the fixture wire (or a pigtail from the same point) to a screw in the box. My assumption was that we no longer needed the screw - attaching the fixture wire to the cable would suffice.

I think what's throwing me off is that this fixture is in the middle of a run. If it were a standard ceiling fixture and there were three wires in the cable, I'd tie the fixture ground and cable ground together, then connect that to the green screw on the mount bracket.

On this point, I'm not certain but you seem to be saying that the previous owner had this set up wrong - two wires to each screw (although to me it's essentially one wire stripped midway and wrapped around the screw) doesn't work. Is the plan for the replacement fixture (two wires to one fixture wire) also wrong? How else would I put a light on this cable?
 
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Old 09-30-08, 04:50 AM
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If your box is metallic the ground wire from the cable should attach to the box and to the grounding lead from the fixture. If the box is non-metallic it would just attach to the fixture lead.

When John said 2 wires under a screw he meant that only 1 wire should be under a screw head. If you have 2 screws you could connect 2 wires, otherwise you would need to pigtail the wires and connect to the single screw.
 
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Old 09-30-08, 09:44 AM
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although to me it's essentially one wire stripped midway and wrapped around the screw
If it is "actually" one wire stripped midway, then it's okay. But if it's only "essentially" one wire stripped midway, then it's probably wrong.

All grounding wires in the box, all grounding screws in the box, and the box itself if it is metal, should all be bonded together.
 
 

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