I am about to purchase a house with knob and tube wiring.
I'd like to protect a circuit of outlets as best as possible (without rewiring with new 3-wire from outlets to breaker box). Same old story, right?
Before you mark this as duplicate let me explain what I will do but I also want to ask about what I think would be better. That's the more interesting question.
What I will do
I will add a GFCI on the outlet closest to the breaker with line and load connected properly. I won't mess grounding anything...just tighten the green screw and wrap the outlet with electrical tape. I will also change all the other outlets in the circuit to standard 3-prong outlets with nothing hooked to ground. I'll test my work and expect an "open ground" error, which is OK. I'll put the stickers on the outlets to indicate that these outlets do not go to ground.
So, first off can you confirm that what I plan to do is "the right thing to do" as being both permissible by the NEC and sensible in your judgement.
What I think would be better
ok, so here is the idea. I won't do it because I know it would be against code. Also please read it through as I don't believe it is anything like a "bootlegged ground" but may sound like one! I think its a great idea, but of course I am biased and mostly uneducated.
I want to ground my modern, 3-prong devices (i.e. I know the "neutral" is grounded at the box, I'm talking about the ground plug). So, on every outlet I would purchase two things
- A dead-front GFCI
- A standard outlet (likely tamper-proof, likely 20A)
Line would go into the GFCI and load would go from the GFCI into the standard outlet. I would have to have a large box to hold those two. I would then send the two (hot/neutral knob and tube) on to the next outlet pair.
Now, for the scheme:
- I would take the ground of the outlet and run it to the neural which is located between the GFCI and breaker.
- I agree that if I were to do this between the ground and neutral at the outlet, this would be a bootlegged ground.
- The ground of the GFCI would remain unattached.
- Rinse and repeat for the other outlets...they all get the pair.
What would happen
- This setup is no worse then the "proper way" described above and I think better.
- The device ground and the outlet ground would typically have little/no voltage and current. That's good. However, if hot happened to hit the ground of the device, current would flow through the bypass, and the GFCI would detect that delta in-out current and throw. This behavior is exactly what a 3-wire grounded system should do.
- A big downside of this is that you need a double box, it might look a little strange in your 100 year old house
- The other big downside is you need to buy and install this set at each outlet.
Would this work as I described and provide improved safety over the "proper way"?