another approach for star grounding

Started by wjurgens on 28 November 2005. 5 replies.

Originally posted at johnlsayers.com, topic 4738.

Hi guys: I'm wiring up 5 room studio in my basement that John Sayers did the design on. I'm in the Kansas City, Kansas area I've been reading through the star grounding threads and have come up with what I think is a slightly easier way to accomplish this first, I'm using plastic boxes, and pulling wire through wood studs. also the outlet plates will be plastic, so the IG & safety ground will be one & the same there's two ways folks are doing this best I can tell 1) pull a home runs of 3 wire ROMEX to each and every outlet black for hot, white for neutral, and bare ground as your isolated ground 2) daisy chain 3 wire ROMEX to multiply outlets, don't use the bare ground. separately pull individual THHN green cable, one for each outlet. depending on the local codes the THHN can either be bundled with the romex, or might need to be run in conduit. For safety, the grounds must be run with the associated conductors OK, so here's my hybrid approach, I've got 30 outles so the idea of using method #1, and pulling 30 separate pieces of romex didn't seem very attractive, not to mention that you'd need 30 breakers back at the panel for each home run. Method #2 still has you pulling lots of THHN cable, along with romex, so it also seemed like a bit of a pain. so the alternate method allows three outlets per run. we will use 14-4G ROMEX, which has a black, white, red, blue, and a bare ground. First, we'll run 14-4G from the panel to the first outlet. Here we'll wire up the hot & neutral and use the bare ground. for the run between the 1st and 2nd outlet we'll again use 14-4G, but won't use the bare ground. For the 2nd outlet we'll use the blue for ground. For the run from the 2nd to 3rd outlet, we'll step down to 14-3G ROMEX which has black, white, red, & bare ground. Again we won't use the bare ground, instead well use the insulated red The red & blue ground wires will need to be recoded with green electrical tape at all exposed ends using the one bare ground wire for the first box. should be no problem, as the other grounds that will be wired through that 1st box will all be insulated. to me this seem lots easier than pullling all the individual THHN cable. It also keeps all the wire in the jacket, which makes for cleaner connections back at the panel, compared to Method #2 which has all the loose THHN cables coming back to the panel. In the case where your not using conduit, I'm not sure there is an approved way to enter the panel with all the loose THHN cable. The 14-4G cable is not to hard to find, Although, typical home center won't have it on the shelf. I found it in Kansas City at an electrical supply house without much trouble. Cost for the 14-4G was $99 for a 250' roll Let me know what you guys think, I'm headed over to the supply house to pick up the 14-4G ROMEX and will start wiring later today thanks! Warren
Interesting idea :D The first thing that runs through my mind is if it will met code requirements, with the appropriate conductor identifiation of course. :?: Andre
I would check w/ your local codes before pulling any wire. This may not be an acceptable practice, although it makes since as far as concept. It may also cost more $$$ doing what you're suggesting. You could install a large conduit (minimum 3/4", maybe a one inch), and you can do similar to a central point for the wires, then break them out to half inch conduit to go to your individual outlets. If you need a better idea of this, give me a little time, and I'll draw something up. Also, if you're running conduit, you'll probably want metal boxes. Also, you can check my thread w/ pictures on conduit runs... Start here, and go through the pix... http://www.johnlsayers.com/phpBB2/viewt ... &start=135
thanks for the feedback I can't think why this would not meet code, we just happen to have some extra ground wires in there. I don't have any inspection to deal with, so safety is the primary concern I have a home wiring book that shows as an example using 14/3G romex with an IGR receptacle. They tied the bare ground to the frame of the IGR, and the red (recoded for green for ground) to the isolated ground. pretty much the same idea just extended to cover multiple outlets. Since I have plastic boxes there's no need for IGR's, and hence only one ground In the threads I was reading, one guy in Colrado got tripped up by the inspector when he ran individual THHN wires for the grounds and cable tied them to the ROMEX. The inspector said that THHN can not be run unprotected in the studs. The inspector made the guy go back and put the THHN in FMC. I guess that's good for protection, and would give you a clean way to enter the panel, on the other hand it seems like a dumb idea from the standpoint of "mutual inductance" (correct term??) where the grounds being in the same proximity as the hot and neutral help to trip the breaker. It seems like putting the grounds in FMC would preclude that even if they are run next to each other. Others in the forums have said that in there areas they are allowed to run THHN wire for grounds outside conduit bundled to the romex The relevant code issues as I see them are 1) are the ground conductors run with the associated hot & nuetral ---- YES 2) are all wires inside a protective casing --- YES 3) non-green ground wires must be recoded green --- YES am I missing anything here? thanks for the help! Warren
The relevant code issues as I see them are 1) are the ground conductors run with the associated hot & nuetral ---- YES 2) are all wires inside a protective casing --- YES 3) non-green ground wires must be recoded green --- YES am I missing anything here?
Nope. Now, here's another option...you can tie hot and neutral to multiple outlets, just be sure to have a "Home Run" for the ground for each outlet.
yes, daisy chaining the hot and neutral across the three outlets in the run is the key to this method. This is the only way you can have enough wire when using 12-4G romex to handle the isolated grounds for three outlets black - hot for all three outlets white - neutral for all three outlets bare copper - ground for first outlet in the run blue - ground for 2nd outlet in the run red - ground for 3rd outlet in the run also using the bare copper in the first box keeps it away from anything that could screw up the isolated ground scheme another key is that you can drop down to 12-3G between the 2nd & 3rd outlet thanks again for the input bye the way Aaron, I looked your thread from the link above. Wow! I'm gonna need to spend some time there.... looks like you covered quite a bit of things I'll running into! Warren