It seems that all too often I get called by someone who wants a ground for their computer where the house wiring has no ground. They've had the idea that I could just take a separate ground wire to the outside or to the panel.
I thought that was a code violation because it would be creating more than one path to ground, or something like that. The best that I could do, I would tell them, is to install a GFCI for personnel protection (per NEC 406.3(D)(3))and a surge suppressor for equipment protection.
But today I was reading an old article by Rex Caudwell in which he says that "neither a surge arrestor at the panel nor a point-of-use arrester at the appliance will work properly without a high quality grounding system to dissipate the surge."
So I decided to investigate further and found me 250.130(c), in which I was surprised to learn that I can, indeed, run a separate EGC from an ungrounded recept right out to the GE or any point along the GE system.
So am I getting this right? And if so, how could I have missed this all these years?
--So I decided to investigate further and found me 250.130(c), in which I was surprised shocked to learn that I can, indeed, run a separate EGC from an ungrounded recept right out to the GE or any point along the GE system.
So am I getting this right? confused And if so, how could I have missed this all these years? blush crazy--
many miss this,not the preferred practice but compliant. unless in Massachusetts. Not allowed here.
The real problem is how you actually connect this. If you read 300.3(A) it says you can't just string THHN back to a ground point. (not a chapter 3 wiring method) On the other hand I think if it is suitably protected that is better than having ungrounded outlets. I have heard of running a new grounded circuit in the accessible areas and tapping off that with fished grounding conductors down/up to the ungrounded outlets through the wall where they are somewhat protected. I would talk to the AHJ and see what they think.
Personally I would just run new cables for grounded outlets in the locations that actually use the ground. (most consumer products have 2 prong plugs anyway)
Okay, Greg. Lts more code to check out. And you're right: the AHJ is a very good idea.
As for "I have heard of running a new grounded circuit in the accessible area and tapping off that with fished grounding conductors...to the ungrounded outlets through the wall where they are somewhat protected" -- if I am able to fish a ground, usually I can fish the entire NM cable (as you suggest in your next paragraph).
"Most consumer products have 2 prong plugs anyway": I am looking at the adapter for this laptop rigth now and it is 3-prong!
As was pointed out, if your plug has a ground pin, the equipment expects a real ground. You are taking your chances with an adapter. I certainly would not connect an ungrounded PC to a grounded phone line. Your modem becomes the fault path.
I'm sorry, but I was under the impression that stringing in a new ground was a practice no longer allowed. That is, all conductors had to be in the same cable / conduit.
I remeber this being depicted when grounds were introduced, and I have encountered houses built with a separate ground strung along with the 2-wire romex. Yet, I have heard many assertions that you can't do this any more ... nor can you just tie it to any handy piece of plumbing.
I do see the need for a real ground path, though. Electronic appliances often use the ground path ... either to always have power ("instant on," timers, motion sensors, etc.), or in order for the surge suppressor to work.