[jlupine]

As I said, the pipe in the house is copper, and the supply from the main in the street is lead.  The lead pipe is not a standard iron-pipe diameter, is not as uniform in diameter as iron pipe, has a bend and a little waviness that is almost impossible for iron, has the dull gray (not black, not galvanized) and splotchy white appearance of lead oxide, is non-magnetic, and has a bulbous, clamped (not threaded, not soldered) connection with a valve, to the other side of which my copper pipe is connected.

My AW Sperry CA-300A ground tester indicates that all of my outlets are grounded.

The electrical system uses conduit as the ground.  My CRC Handbook of Chemistry and Physics lists the following electrical resistivity in microhms/cm at 20 degrees Celsius:

Cu - 1.673   Fe - 9.71    Pb - 20.648

The alloys in the pipe would probably not have these elemental values but should be fairly close.  I expect the steel conduit to be reasonably close to the iron value as well.  So, a short run of lead to the soil is probably a lot lower in electrical resistance than the much longer run through the conduit.

My copper pipe also extends outside and into, possibly through, the sidewalk to supply the lawn sprinkler system.  I don't know where the copper changes into the PVC that I see whenever I change a sprinkler head, but it's possible that the copper actually makes it to earth before the change.
 
I haven't checked the code, but I doubt that cities would retroactively outlaw their own lead supply pipes since they'd have to assume the expense of replacing them.  Certainly, modern code requires that new construction would make a  less toxic choice, but I don't see how they could require the homeowners to replace the city's supply pipes.  

Incidentally, it seems to me that a lot of plumbers use Sn-Sb solder on copper pipe.  I think of antimony as highly toxic:  does less of it leach out of the joint than lead in Sn-Pb solders ?  I prefer the Sn-Cu solders that I've seen.  I don't know what they cost, but they melt and flow fine.  I wonder why antimony is still permitted.

Jan

[Dan Banquer]

"The alloys in the pipe would probably not have these elemental values but should be fairly close. I expect the steel conduit to be reasonably close to the iron value as well. So, a short run of lead to the soil is probably a lot lower in electrical resistance than the much longer run through the conduit."
  The above is true but I think we need to look back to the classic definition of earth ground which is a copper rod 1,000 ft long inserted straight down into the earth. Theoretically this allows any amount of charge to be "dumped to earth." Since this is not practical the connection to the city water system gives a much larger amount of conductor into the earth than just the usual eight foot rod. There is one caveat however. Many of us have noticed that new main water pipies that are being laid don't exactly look like cast iron but alot more like plastic. This makes me wonder if any of the city officials bother to tell their constituents that the earth ground through the water pipes will now be severley degraded.  In addition I watched a news program this weekend about the lead water pipes in the Washington DC area and the possible problems it was causing.
  It would appear that both the water pipe connection and the ground rod may be necessary. I would still consult an electrician however before doing anything.
             d.b.

[DVV]

"The alloys in the pipe would probably not have these elemental values but should be fairly close. I expect the steel conduit to be reasonably close to the iron value as well. So, a short run of lead to the soil is probably a lot lower in electrical resistance than the much longer run through the conduit."
  The above is true but I think we need to look back to the classic definition of earth ground which is a copper rod 1,000 ft long inserted straight down into the earth. Theoretically this allows any am ...

One more point, an unknown - it's important to be sure just how well grounded are the water pumps along the way, from the reservoir/water factory to one's home. I have had an opportunity to see a friend discover his own apartment building water pump was probably not grounded at all. In view of the required power those electric motors need to have, this is no small problem.

Exactly the same thing happens when people use heating pipes for grounding; they discover more often than not that heating pipe installations are seldom really grounded. Thus, instead of receiving dead quiet, they end up receiving nice hum and eddy currents.

Theoretical ground, as outlined in IEC documents, should have a voltage potential of 0.8V or less and an impedance of 2 ohms or less. I have yet to see somebody lucky enough to have this, with perhaps the exception of those fortunate enough to own their own houses who have invested in at least 10 foot copper rods stuck into the ground, and without hitting or even touching any pipe down there.

This is the reasoning behind separate ground filtering, I think - you can't really have it, so you may as well be resigned to not having it and do what you can to make it as close to the ideal as you can. Simply isolating it is, in my view, sheer nonsense, because all too often, what you end up having is no proper grounding at all.

Hum loops are certainly possible, but invariably they appear when some ground point assumes the ideal ground potential and actually sees all but that theoretical value. In other words, a poor design job in which nobody bothered to look into separate ground potentials.

Here's a small practical example. Some years ago, I designed a very simple power amp. It worked, but the level of distortion was higher than I wanted it to be. Well, I worked by behind off trying to get it down, until a few months later it dawned on me that my feedback "ground" was at a much higher potential than it should ever have been due to poor grounding in my apartment building. A simple 10 ohm resistor between the NFB ground and the power supply ground ended that; however, I must add there is no math known to man which can work out which resistor will do the job, it's strictly heueristic, try and see. That 10 ohm resistor was about the 15th or 16th I tried.

Ground is the Al Quaida of audio, the insiduous and invisible enemy.

Cheers,
DVV

[Dan Banquer]

"Theoretical ground, as outlined in IEC documents, should have a voltage potential of 0.8V or less and an impedance of 2 ohms or less. I have yet to see somebody lucky enough to have this, with perhaps the exception of those fortunate enough to own their own houses who have invested in at least 10 foot copper rods stuck into the ground, and without hitting or even touching any pipe down there."
To the best of my knowledge here in the states that is generally not an issue. However I really do wonder how things work in a high rise building. Are there any electricians out there who have experience in this area?
When I had a distributor in Taiwan he would ground the equipment to the widow sill. This sounds silly at first except that in Taiwan there is very little of the typical woodframe construction we find here in the States and most folks live in high rise buildings. According to him at the time he was doing it he claimed it worked just fine. My guess is that the entire frame of the high rise building was tied to earth ground.
I loved the story about the water pumps.
             d.b.

[DVV]

To the best of my knowledge here in the states that is generally not an issue. However I really do wonder how things work in a high rise building. Are there any electricians out there who have experience in this area?

Well, elsewhere in the world, people make houses using bricks, Dan, not wood. Maybe stone as well. In Europe, when you say your house is made of wood, everybody thinks you are talking about your hunting lodge, or perchance your summer house.

When I had a distributor in Taiwan he would ground the equipment to the widow sill. This sounds silly at first except that in Taiwan there is very little of the typical woodframe construction we find here in the States and most folks live in high rise buildings. According to him at the time he was doing it he claimed it worked just fine. My guess is that the entire frame of the high rise building was tied to earth ground.

You just answered your own question, Dan. That's about what people living in high rise do for grounding, or use water pipes, or heating conduits. Or drive nails into walls.

BTW, does my 8th floor count as high rise? The condors still fly over me. But seriously, one thing high rise is good for is keeping company with sparrows. I don't much like birds in general, but I compensate by just loving sparrows. I feed them, and have a small gang of those tongue-in-cheek little rascals turning up rather regularly.

Well, I have to console myself with SOMETHING, right? And the official mascot of the city of Belgrade is a sparrow.

I loved the story about the water pumps.

You wouldn't if it was you in question, believe me. And another thing - you can hear them humming if you get close to them during the heating season.

Cheers,
DVV

[Psychicanimal]

Well, I have to console myself with SOMETHING, right?

As long as it's not your own hand!!!

   

[Pirate]

I have a freind who was actually called out to a home where someone was shocked while taking a shower. Furthur investigation showed where a painter had removed the breaker box panel to paint. When he reinstalled the panel somehow he screwed directly into a live circuit. This in turn made all the plumbing in the house hot when a light switch in the bathroom was used to turn on the light . Fortunately no one was seriously hurt. This is why plumbing is used for a ground.

Back in the late 1800's to the mid 1930's lead pipe was used here in service connections because of its flexability. Never was lead pipe used for mains. Yes, the local water districts spent big dollars to change out all of these types of connections once the problem was detected. I believe the Pasadena area was mostly effected.

Adding an extra grounding rod is easy as long as you do not change your existing ground. A 5/8 x 8 ft  solid copper rod is driven completly below grade next to an exterior water pipe. Usually where a hose bib is located. Using special GROUNDING ROD CONNECTORS a minimum # 6 SOLID  continuous copper wire is used to connect the two together. Some areas may use a 10' stainless rod depending on soil types.
When it comes to grounding more is always better.

[Gordy]

I've been told that the alloy grounding rods are the thing to use as they will not oxidize/degrade.  Please correct me if I'm wrong because I'm about to buy one to replace or parallel my copper rod (which is only 6' deep!).  Thanks!

Gordy

[Dan Banquer]

If a ceritfied electrcian says it's O.K. to use an alloy grounding rod; I'm not going to argue the point.
                       d.b.