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I'm planning on running some schedule 80 PVC conduit in my garage to add extra outlets. At the same time I want to ground the 2 post rack I have in my garage. A few related questions that appear unique enough because I couldn't find answers online.

  1. Everything I looked up says I need #6 ground from rack to panel to be "doing it properly". Is #6 really needed? The run is about 15'.
    • I was going to just run the ground in the PVC conduit for the outlets and use it as the ground for those outlets and the rack, any issues here?
  2. Assuming the answer to the first question is yes; since I only need the #6 sized ground for the panel can I step down the ground to #12 or #14 (depending on size of circuit) with pigtails on the outlets? Also, for the last outlet or two past the rack? I know stepping down the hot and neutral lines is prohibited but what about the ground wire?
  3. And while I'm asking questions, are there any distance from the floor requirements (or good practice) for mounting PVC conduit on the wall.

Thanks in advance!

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  • We need more info. Is this a rack for running PCs/servers? What sort of power is going from subpanel to rack? Is the PVC conduit going outside between buildings? How did you arrive at 6 AWG ground? – Harper - Reinstate Monica Jun 4 '17 at 6:02
  • You don't need that much ground wire to bond the metal of the rack. A #12 will do for a 20 amp circuit. According to Table 250.122 of the NEC #6 copper wire is only required for a 200 amp branch circuit. What have you been reading? – ArchonOSX Jun 4 '17 at 9:27
  • More info would be good. "doing it properly" basically means a straight run; no splices. As for size, you might want to include information about how much current you're talking about. Start with the number of outlets. – SDsolar Jun 4 '17 at 11:15
  • Yes the rack is a 2 post with servers and other network equipment in it. I work in IT so doing some home projects is fun. :) Everything I read for grounding racks and Bussbars says 6AWG. Makes sense if this is the Bussbar in a server or switch room back to building but not so much for a single rack. PVC is going to be mounted on wall in the inside of garage, basically I don't feel like pulling off drywall. As of now, I am planning on 20 Amp circuit 3-5 outlets. Breaker or first outlet will be GFCI. Should I do a single ground run and a separate ground for the outlets? – ErikW Jun 4 '17 at 18:17
  • a link to one of the many different things I have read that suggests #6. cooperindustries.com/content/dam/public/bline/Resources/Library/… – ErikW Jun 4 '17 at 18:22
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The answer is no if you're looking for a simple answer.

More complex answer - What everyone is trying to say in the comments is that you can size the wire according to Table 250.122 in the NEC. This table allows you to size the equipment grounding conductors according to the breaker size protecting the circuit. Example - If your breaker is a 50A then you're equipment ground should be a #8 from beginning to end and there is no downsizing. Keep in mind that the NEC has a complete Article 250 Grounding and Bonded and is one of the most complicated Articles in the NEC.

In answer to part 3 of your question. There is no distance to floor for running PVC other than it should be installed in a correct and workmanship manner. Also it should be protected from any unnecessary damage. A full description is in Article 352 Rigid Polyvinyl Chloride Conduit Type PVC.

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  • Thanks. It sounds like what I need to do is run the properly sized ground for the outlets (#12 or bigger for 20A outlets) and run a separate ground for the rack. I was just hoping to run (1) #8 or #10 ground wire for use at every outlet in the chain and then tie a rack ground in at the outlet box nearest the rack. – ErikW Jun 6 '17 at 4:34

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