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Daneel 07-17-2011 03:50 PM

rewiring old house-multiple earth grounds
 
I am sure there have been many reported wirings of old houses.

I am gradually rewiring an old house (log cabin). I think the original wiring must have been done by the seat-of-the-pants of whoever was doing the wiring -- different people at different times.

Most of the circuits are two-wire. There is no separation in the main fuse panel between neutrals and a few safety grounds.

I am finding multiple connections between neutrals and safety-grounds and "earth" grounds, for example...

fuse panel neutral to meter base neutral to ground rod (3/4" EMT);
garbage disposal neutral to cold water pipe under sink;
hot water heater (10 A @240 VAC) safety-ground to cold water pipe;
bathroom junction box neutral to well (2" pipe perhaps 20-25 feet into the earth).

Is it dangerous to have multiple earth-grounds throughout the house? Or is it just screwy and not to code?

My understanding is that in the main panel (and only there) the neutral bar should be bonded to the safety-ground bar; that the safety-ground should be connected to a ground rod; and that there may also be a connection to a well or cold water pipe.

Is this correct?

Can the ground rod be connected either to the main panel or to the meter base?

I am planning on replacing the fuse panel with a 100A or 200A breaker panel. How long should the ground rod be? What diameter? Any alternatives to a copper rod? What guage for the safety ground to the panel?

Thanks for your help,
Daneel

a7ecorsair 07-17-2011 04:18 PM

Your main panel, the panel that is connected directly to the meter socket, has to have the grounding electrode conductor, that thick piece of copper wire, connected to the neutral bar and then to the grounding electrode. The grounding electrode can be different things. Could be a water pipe, a ground rod, or a concrete encased electrode.
Sticking a rod in the ground and tying a wire to it or just connecting to any old piece of pipe doesn't create an effective ground.

gregzoll 07-17-2011 04:45 PM

Length of the rod, depends on how deep you can drive it. 8 feet is the norm, but if in a rocky area, you may have to use a UFER, or other method to ground, if not able to drive the ground rod that deep. I would say that you really need to read through the NEC to understand what you are doing, before you put your life, and others lives at risk.

a7ecorsair 07-17-2011 05:03 PM

Quote:

Originally Posted by Daneel (Post 688057)

Most of the circuits are two-wire. There is no separation in the main fuse panel between neutrals and a few safety grounds.

This could be O.K.

I am finding multiple connections between neutrals and safety-grounds and "earth" grounds, for example...

fuse panel neutral to meter base neutral to ground rod (3/4" EMT);
This could be O.K. too, depending on where the grounding conductor is attached.
garbage disposal neutral to cold water pipe under sink;
Not good. The neutral is connect to the water pipe? Is there a neutral line coming in with the power wire too?
hot water heater (10 A @240 VAC) safety-ground to cold water pipe;
bathroom junction box neutral to well (2" pipe perhaps 20-25 feet into the earth).
Really...gee, it does need some work.

Is it dangerous to have multiple earth-grounds throughout the house? Or is it just screwy and not to code? Dangerous and ineffective

My understanding is that in the main panel (and only there) the neutral bar should be bonded to the safety-ground bar; that the safety-ground should be connected to a ground rod; and that there may also be a connection to a well or cold water pipe.

Can the ground rod be connected either to the main panel or to the meter base?
See the other reply

I am planning on replacing the fuse panel with a 100A or 200A breaker panel. How long should the ground rod be?
8 feet
What diameter?
1/2" in most cases
Any alternatives to a copper rod?
UFER or concrete encased electrode.
What guage for the safety ground to the panel?
#6 copper works because it doesn't need protection.

Thanks for your help,
Daneel

Leave the work safety out when mentioning grounds.
Your main panel neutral and ground bars can vary depending on how the panel is made. In your main panel, ground wires and neutral wires can be connected to the same bar. If the bar is an add on, it has to have a connection to the main neutral bar with an approved link and cannot be just the panel case.

mpoulton 07-17-2011 06:39 PM

Quote:

Originally Posted by Daneel (Post 688057)
garbage disposal neutral to cold water pipe under sink;
...
bathroom junction box neutral to well (2" pipe perhaps 20-25 feet into the earth).

These two may be extremely dangerous. Are the neutrals connected ONLY to the pipes, or do the wires ALSO run back to the neutral/ground bar in the panel? If they are only connected to the pipes, then the pipes (and, in the case of the well, the earth itself) are being used as the return current conductor for those loads. This has the potential to electrify your plumbing. Very bad.

gregzoll 07-17-2011 07:16 PM

I am starting to think that the Bubba that wired this, intended to use the copper in the house for the path return, or thought that they were working on a vehicle. If I personally had to deal with it, I would have the house disco'd by the POCO, pull all wiring, and rewire properly, and have inspected before having any power allowed back into the main.

Daneel 07-17-2011 08:13 PM

neutrals go back to main panel
 
All the circuits I have checked DO have hot and neutral wires going back to the main panel. No "car wiring" so far.

Sorry, I for got to mention this. It would never occurred to me to have a single wired circuit. If I find anything like this I will disconnect it immediately.

Thank you for your cautionary replies.
Daneel

gregzoll 07-17-2011 08:41 PM

You are welcome to post a picture of the panel if you wish, to get further input. You may have to use a Genset while trying to get the rooms rewired. Have you drawn out a plan on paper, so that you can keep track of your progress, and also able to determine all circuits needed for this cabin?

Anti-wingnut 07-17-2011 08:54 PM

It's Ufer, not UFER. As in Mr. Ufer

a7ecorsair 07-17-2011 09:17 PM

Quote:

Originally Posted by Anti-wingnut (Post 688296)
It's Ufer, not UFER. As in Mr. Ufer

Sorry for the sloppy typing and not giving proper credit to Herbert G. Ufer for designing the concrete encased electrode...


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