Grounding/bonding question

[fyrmnk]

Hi all, just curious when it became required that the main water line not be the only source of ground for the service.

I always recommend ground rods/wire be installed on older homes with only the water line connected to supplement it, but curious when that became required. Thanks in advance.

[Jim Katen]

Originally posted by fyrmnk

Hi all, just curious when it became required that the main water line not be the only source of ground for the service.

Finding the answer's a bit tricky since my NEC collection has gaps. Here's what I know:

The 1951 edition was the first to require the use of a supplemental electrode if the buried portion of the water pipe was less than ten feet long or if there were "some likelihood of the piping system being disconnected." (In my mind, that means *any* water piping system, but I digress.) This requirement did not exist in the 1947 edition.

The 1962 edition was the first to recognize plastic fittings. In addition to the less-than-ten-feet and likelihood-of-disconnected provisions, they added "isolated through the use of non-metallic piping or insulated couplings" to the list of conditions that would trigger the requirement for a supplementary electrode.

The 1971 edition was basically the same as the 1962 edition in this regard. Then there's a 10-year gap in my collection.

The 1981 edition calls for a supplementary electrode no matter the condition of the water pipe. "A metal underground water pipe shall be supplemented by an additional electrode of a type specified blah, blah, blah." There are no change bars next to this section, so it must have appeared in either the 1975 or 1978 editions.

So the short answer to your question is 1975 or 1978. Of course in some cases it was 1951.

I always recommend ground rods/wire be installed on older homes with only the water line connected to supplement it, but curious when that became required. Thanks in advance.

I don't recommend adding a supplementary electrode on older homes unless I see a problem with the water pipe. Mostly it's because I don't see how adding the supplementary electrode makes the system any safer. Perhaps I should reconsider my position.

How many others do what Kevin does? If so, what do you say in your reports about why it's a good idea?

- Jim Katen, Oregon

[kurt]

I don't say a thing. It seems the GEC is not the primary path anyway; too much resistance in the earth, and all that, no?

[fyrmnk]

Originally posted by kurt

I don't say a thing. It seems the GEC is not the primary path anyway; too much resistance in the earth, and all that, no?

Since water lines must not be the only ground connection now, and there's no way to verify that the water line is metal in contact with the ground for at least 10' out from the home or that it provides less than 25 ohms resistance is why I recommend it.

Is it not done primarily for the lightning protection? Maybe I'm just overly anal on the grounding. I worked many years for a commercial electrician (grant it, mostly communication towers and tops of high rises) and we did an ungodly amount of grounding, although in most cases that fell under lightning protection, not just system grounding.

I don't make a big deal about recommending the supplement, I just cite the same reasons I listed above. I'm certainly not against changing my position if need be, keep the feedback coming.

Thanks again.

[kurt]

In my case, I'm looking @ old properties w/lead water entrance 90% of the time. The other 10% are new copper. Our plumbers union won't allow any form of plastic; never has. So, I don't have the "is it 10' of metal?" concern; I know it's metal.

The earth is not a particularly good grounding path; my oafish understanding is that the earth has relatively high resistance, and stray current is going to travel through the neutral back to the transformer. Honestly, I don't know why we have the connection to earth; probably does have to do w/wild spikes like lightning.

After that, I certainly wouldn't argue against additional grounding paths. If it makes someone feel they've gone the extra yard, go for it.

[mcramer]

Originally posted by kurt

In my case, I'm looking @ old properties w/lead water entrance 90% of the time. The other 10% are new copper. Our plumbers union won't allow any form of plastic; never has. So, I don't have the "is it 10' of metal?" concern; I know it's metal.

The earth is not a particularly good grounding path; my oafish understanding is that the earth has relatively high resistance, and stray current is going to travel through the neutral back to the transformer. Honestly, I don't know why we have the connection to earth; probably does have to do w/wild spikes like lightning.

After that, I certainly wouldn't argue against additional grounding paths. If it makes someone feel they've gone the extra yard, go for it.

Grounding of the service has nothing to do with clearing faults, it's all about protection from outside sources such as lightning, higher voltage line falling on a lower voltage line, etc.

[kurt]

Thanks. That's (more or less) what I figured. It's taken me about 4 years & 11 months to understand how the grounding/bonding/earthing thing works, and I still have to repeat it over & over for it to sink in.

Calling it "earthing" might be a better idea, since it doesn't have anything to do w/clearing ground faults.

[PAbernathy]

Yep....just another one of the MANY Grounding & Bonding myths we see in the seminar world. Finally glad people are catching on that the Ground Rod and other electrodes only play a role in Lightning, High Voltage Surges and Contact Surges.....not in the function of the OCPD and so on.

In my seminars I have a fast and easy way to explain it...and it is catching on thanks to educators and people like Mr. Holt.