How Can My 1924 Water Main Be Galvanized If It Still Works? & Best Grounding Methods

D107

We have been planning on preventively replacing our 1924 3/4" water main. Almost everyone else's --galvanized--on the block has long ago failed. Ours works fine, no noticeable pressure issues. I just had to lower house pressure from 70 to 60. The box is on the street a 20 feet away and the pipe comes through the floor and attracts to magnets so I assume that means it's galvanized. Could it be some other metal? (Westchester ny). Don't want to replace it if I don't have to. Our thought was that if we waited until it failed it could be at a very inconvenient time and also we had no idea WHERE it would fail, possibly near the house and cause a flood inside and out.

delta T

D107 said:

Our thought was that if we waited until it failed it could be at a very inconvenient time and also we had no idea WHERE it would fail, possibly near the house and cause a flood inside and out.

This is the crux of it. Buried galvanized will eventually fail. I have replaced many galvanized services in my area (southern CO). The problem is, that imminent failure may not show any signs before hand. Flow restriction is not always evident and everything will seem fine.....until it isn't. Most of the failed lines that I pull out are so thin that you can crush them in your hands.

Another consideration is that often old galvanized services were connected to the main using a short piece of lead piping. While this may or may not be a real problem (depends largely on the water chemistry involved, see Flint, MI) I think we can all agree that having lead in potable water system is generally something to be avoided.

I would strongly advise that you start planning for replacement and do it on your terms and not on an emergency basis.

I say all this as a plumber who has a 100+ year old 1/2" galvanized service with a lead connection to the main that I still haven't replaced yet.....every now and then I hear my washing machine shutting off with a thump and wonder.....is today gonna be the day? I have plans to replace it next summer when we tear the front yard up for some major landscaping renovation, I just hope it lasts me that long.....

pecmsg

D107 said:

We have been planning on preventively replacing our 1924 3/4" water main. Almost everyone else's --galvanized--on the block has long ago failed. Ours works fine, no noticeable pressure issues. I just had to lower house pressure from 70 to 60. The box is on the street a 20 feet away and the pipe comes through the floor and attracts to magnets so I assume that means it's galvanized. Could it be some other metal? (Westchester ny). Don't want to replace it if I don't have to. Our thought was that if we waited until it failed it could be at a very inconvenient time and also we had no idea WHERE it would fail, possibly near the house and cause a flood inside and out.

You know its galv, why wait? What happens when it fails in the middle of the winter from frost heaves. No water service, higher repair bills because you don't have time to shop, poor at best workmanship for the same reason.

Do you wait until the cars dead to replace it?

D107

@pecmsg We are not waiting--have two estimates coming-- but since the plumber expressed surprise it still works and I couldn't understand how there'd be no flow problems if it was galvanized but @delta T answered that easily.

Plumber wants to install an angle stop ball valve where the new main will enter the bottom of the foundation wall--guess it saves elbows. Then the water meter, then a ball valve, then PRV. Never heard of those angle stop ball valves used for mains. Hope to do this in a few weeks. They'll use the boring method, and install 3/4" --or 1" my preference--K copper coil. No sleeve.

Have also been advised to install a dielectric union since the main offers a parallel neutral path for electric current flow. Sometimes they insert a run of non-conductive pipe in the main to break the conductivity. See attached pdf.

Jamie Hall

If you decide to install a dielectric union.... make sure that you still have a solid ground connection somewhere. The neutral from the electrical service is not -- repeat NOT -- a ground.

D107

@Jamie Hall Yes, as I understand it and the electrician will have to verify, there needs to be at least two buried ground rods. And while main is being replaced they should be using jumpers. In fact the advice has been to call utility company to come out and check the neutral connections to make sure there isn't an issue with the neutral path. "These connections should be checked at the pole as well as the electrical meter...and the electrician can check the netural connection in the meter box as well as within the panel." (rules vary by locality in terms of that the utility will agree to check.)

pecmsg

Can't say I'm familiar with breaking the grounding ability of the cold water line underground. Not done in Suffolk county!

D107

@pecmsg It is my understanding the the new national code no longer allows--I guess on new installations--the water main to be used as a ground; grounds must be from buried cables. Of course I'll have my electrician verify this. Plumber explained to me that he will re-ground the system as he found it; if I want to bring it up to code I'll have to get the electrician to do it.

EBEBRATT-Ed

@D107
Do what you want but I would install a copper water main and I would NOT use any dielectric fittings unless your utility or electrical inspector insists on this.

Ground rods are very poor grounding electrodes. If your neutral wire from the pole is connected properly you will have no or very low current flowing on the water main.

You want to have good grounding in case of lightning strikes a copper water pipe improves this grounding.

The best ground is a copper wire or plate buried in the concrete footing. This can't be done with an existing home.
Master Electrician in 3 states

EBEBRATT-Ed

Also, my brother bought an old house about 20 years ago and moved in in September. He has a well with a galvanized pipe from the well to the house. In the middle of December all of a sudden and with no warning he had no water...not a drop. It didn't make any sense as the day before the water was fine.

But that's how quick the galvanized plugged up. We tried blowing it out and snaking it from both ends with no success.

Digging a trench with frost in the ground is no fun

Fred

I had galvanized from the street into my 1902 house until about four years ago and the majority of the houses in this area, same vintage still have galvanized. It's a crap shoot when it's that old. Also, a lot of times what you think is galvanized is old lead pipe. Not good, especially for young children. Lead will leach.

JUGHNE

Some "good" galv pipes will start to leak if they are uncovered, the weight and compaction of the earth is holding them intact.

Most would be reluctant to put a pipe wrench on that.

On a nice warm, sunny day you would get a good install.
Opposite conditions will give you a "git er done" job costing more.

You said you lowered your inside pressure, what is the city pressure....maybe 100PSI....that can push a lot of water thru a restricted pipe to your pressure regulator.

Jamie Hall

EBEBRATT-Ed said:

@D107
Do what you want but I would install a copper water main and I would NOT use any dielectric fittings unless your utility or electrical inspector insists on this.

Ground rods are very poor grounding electrodes. If your neutral wire from the pole is connected properly you will have no or very low current flowing on the water main.

You want to have good grounding in case of lightning strikes a copper water pipe improves this grounding.

The best ground is a copper wire or plate buried in the concrete footing. This can't be done with an existing home.
Master Electrician in 3 states

Amen, brother @EBEBRATT-Ed .

That said... what we did, back in 1960 when the well was installed on the farm where Cedric lives, is we abandoned all the old galvanized pipe in place (there was a lot of it!) and left the system ground attached to it. The "new" well lines are polyethylene... and we are hoping they last...

Intplm.

@D107 Good move replacing the galvanized pipe now and on your schedule rather than later. Galvanized at that age is to be commended for it longevity and retired for it deterioration.

I have galvanized too. Every day it gets closer to full replacement.

Maybe use a brass fitting rather than a dielectric between the two foreign metals.

jumper

Weren't other ferrous materials used besides galvanized gray in those olden days?

D107

EBEBRATT-Ed said:

@D107
Do what you want but I would install a copper water main and I would NOT use any dielectric fittings unless your utility or electrical inspector insists on this. Ground rods are very poor grounding electrodes. If your neutral wire from the pole is connected properly you will have no or very low current flowing on the water main.

@EBEBRATT-Ed With all the different jurisdictions on this it gets a little confusing. I've been told that the new national electric code prefers grounding electrodes to water mains, though I'm more likely to trust your expertise than theirs. Why would they do that? Fear of the pipe becoming a 'partial, if not only, neutral path?' How would that happen, over time? A good connection goes bad? And your view seems to be that very low current flowing on the water main is a better risk than not having a good enough ground. When you say 'if your neutral wire from the pole is connected properly...' which pole are you referring to?

My plumber pointed out that the ground connections at the house are all secondary to the main ground--from the street? not sure what that means.

I had the service upgraded to 200 amps a decade ago, they put in new grounding rods, etc. I do see a piece of old BX cable that was detached--maybe that was the old ground embedded in the 1924 foundation?

Jamie Hall

In theory (right...) the neutral should be solid to the pole and thence to the transformer -- and the transformer should be grounded. Your neutrals (which are connected to the neutral to the pole) in the building wiring should also be grounded at the main switch box -- and nowhere else.

So you have a total of four wires to think about. The two hot lines coming in and the neutral coming in and the ground. If everything is wired the way it should be, there should be less current in the neutral than either of the hots (that depends on how the loads are distributed) and none at all in the ground. However, there is some resistance in the neutral to the pole, so unless the loads are perfectly balanced (never happens!) there will be a slight voltage difference between the neutral and the ground at your house -- and hence there will be a small current in the ground at your house. If the grounding is good at your house, it will hold the actual voltage there very close to zero. If it isn't, or something evil happens to the neutral to the pole or the ground at the transformer, there is a potential for higher voltages -- which can be a shocking surprise. So... you need a good ground.

Not to mention that a really good ground will limit -- not eliminate -- the damage in the event of a lightning strike or wires coming down and getting crossed.

Now... why not the water main? I think there are at least three reasons. The first is that using the water main would be fine -- if you could be sure that it was all metal and that it would stay that way. You can't. The tendency today is to use polyethylene for at least parts of the main, and you can't be sure that what metal is left in the ground is enough. Second, if there is an impressed current on the pipe, and the pipe is partly one metal and partly another -- say some copper and some galvanized -- that can accelerate corrosion and leakage. The third is that someone may put in a dielectric union between the ground clamp and the pipe outside the building -- and then you have no ground at all.

D107

@Jamie Hall Thanks so it sounds like you're saying the water main cannot be relied upon to be the ground--so you prefer grounding rods, or grounding rods AND the main? And that is why the national code was changed? And I should have my neutral checked by the utility? or my electrician? And that I should or should not follow the other local advice I got about either using a dielectric union or a 6 inch piece of pvc to act as an insulator against current flow? Supposedly the installation of a secondary surge arrester can be installed across the dielectric union to protect the home from lightning strikes. All this is quite above my pay grade, but as with many house projects and Wall advice, one learns a hell of a lot.

Jamie Hall

No harm to a secondary surge arrestor across a dielectric union or chunk of PVC or poly serving the same purpose. They carry no current at all unless there is a lightning or other high voltage spike.

The primary surge arrestor, though, if you have one, should be connected to ground at the main switchbox.

Do I prefer ground rods? Truth to tell, like @EBEBRATT-Ed , not really... it's remarkably hard to get a really good ground with them. It depends so much on the soil and soil moisture. But... the advantage is that they are under the control of just one trade -- the electrician -- and he doesn't have to worry about a plumber getting clever, and the plumber doesn't have to worry about getting zapped.

Either your electrician or the utility can check the condition of the neutral -- but the odds are good that you will know if there is a problem. The current come into your house on the two hots, and all your 110 volt conventional circuits are connected to one or the other -- but not both. If the neutral is intact, it doesn't matter what loads you have connected to which hot -- the neutral will carry the unbalanced current away, and the voltage won't change. However... if there is a problem with the neutral, when you have unbalanced loads which you almost always will you will notice the lights on one side or the other getting much brighter or dimmer depending on what's plugged in and turned on where (not true if you are using LED lights -- they'll just burn out prematurely instead!)

JUGHNE

Pole is power pole in alley or utility high voltage transformer location.

Today UFER grounds are required by the National Electric Code for new buildings.
This went into effect in the last 6-9 years or so.
It is a copper wire connected to a minimum of 20' footing rebar, the footing would be contact with the lowest excavation of the building. Typically all the rebar is tied together so you have the entire perimeter of the building as grounding electrode. The weight of the building on the footing insures good contact with the earth. This bare ground wire would connect in the main service disconnect panel to the neutral/white lugs. After that point the neutral/white and bare/green ground are not to be reconnected anywhere. The system went from a 3 wire service to a 4 wire system.

Now with all that good earth contact of concrete, perhaps 8' below grade, held down by the weight of your house, you have to run only #4 copper from your lavish ground electrode to the main service.....why that small??.....because that is all the UFER ground system could dissipate. (personally I use #2 as it is more durable)

8' long ground rods are supposed to be driven so the head is a foot below grade, that puts it down to 9'. Now the max required wire to ground rods is #6....size, smaller than the UFER requirements. Smaller for the same reasoning that that is all it can dissipate.

Now a metallic water line requires a copper wire size that will dissipate the entire current available based on the size of the main service conductors. Your 200 amp service may require #4 copper. The more current available because of wire delivery size coming into your system could drive that grounding wire to the water line up to 3/0 copper (about 1/2" diameter).

So the water line is the best electrode and here we must use it, if it is available, in addition to the UFER and ground rods.
Typically in the past your copper water line was connected to a steel/iron cement lined city main. All other copper/steel water services were connected and all would have a ground wire connected to the power utility system. This created a great grounding grid.

The UFER was added to the code because of future use of non-conductive water piping being installed both for city mains and service lines.

If required to use a dielectric union, (always a potential leaker), you want to jumper around it just like a water meter.

D107

@JUGHNE This is a great clinic on grounding. I'm enclosing some photos. The panel (from 2006) has a surge protector and looks like two black ground wires? By the water main, you'll see the new copper grounds connected to the main, shutoff, PRV, meter, then it keeps going then goes up a copper water pipe and ends on that pipe.

You will also see the old ground, a piece of BX coming out of a pipe, that bends to a 90 that hugs the wall a few feet --pipe now green colored--then goes up and up and ends I don't know where. If it was going to connect back to where the electric comes into the building, it would have to 90 again and run about 10 feet to the left. Not sure if this old line is of any value or use.

Your description of the buried building ground seems like the description that @EBEBRATT-Ed made about such grounds being not doable in a residence if I understood him correctly--I'd understand it's hard to do after the building's already up.

Your suggestion of using jumpers to get around the PVC or dielectric would seem to circumvent the purpose of the circuit interruption, so you too seem to be saying that the gain of the better ground of the metal water main justifies any risk from a compromised neutral connection, or pipe corrosion or elevated magnetic fields.

Jamie Hall

Grounding an existing building is always a problem -- particularly if it is older (such as stone, not concrete foundations!) or cinder or concrete block -- neither of which help at all.

But if you think grounding a single building gets interesting... try looking through the code rules for farms, which often have a number of outlying buildings, often with very large loads.

JUGHNE

The Code book is often referred to as the "Book of Exceptions".
There are about 750 pages in the book plus 114 pages of tables.
Of the 750, 35 pages are dedicated to grounding & bonding.

Every other section refers back to the 35 pages for each requirements for that section.....again exceptions are noted that have you bouncing all the book.

The grounding electrode wire to your water service today, IIRC must be from the service disconnect panel unbroken to the city side of the water meter. It looks like your old conductor may have been in steel conduit. This requires special connections on the pipe to insure that each end is at the same potential in the event of major current flow. Today one would use PVC or simply run it without pipe provided physical protection is afforded.

Also in the book there is a requirement that all permanent metallic objects that may become energized must be bonded to this system. This includes all conductive piping, ductwork, tanks and gas piping. This is often overlooked by inspectors.

Jamie, are you required to run 4 wire services to your outbuildings? (another can of worms)

Jamie Hall

@JUGHNE -- indeed we are. And a first class pain in the neck it is, too. On the other hand, the whole show is grounded through the 200 foot deep 6 inch steel well casing... seems to work!

On the "anything that can become energized" thing -- especially with critters. Most livestock can tolerate a brief jolt (like milliseconds) of several thousand volts -- that's why electric fence works (and the ground terminal of the charger has to be grounded... here we go again...) but even a few seconds of 120 VAC will kill a horse. So... one gets kind of ingenious.

JUGHNE

Here in NE, the only total public power state, we have the REA companies that do the majority of farmsteads.
Almost all farms get a manual transfer switch rated at 200amps single phase. These are typically centrally located in the farmstead. "Maypole" is the term used. Most farms have a PTO tractor driven generator they park at the transfer switch when needed.
These do not have any form of overcurrent protection in them.
Therefore the state electrical board considers that transfer switch to be a "convenience disconnect". With that label then from the Maypole we can run 3 wire underground or overhead to any place on the farm. Each drop then is treated as a separate service.
Now if a permanently installed auto transfer gen set is placed at the Maypole, from the overcurrent protection of the gen set we should be going 4 wire. Fortunately existing ag installs are not subject in inspection.

Years ago I spun my wheels looking for stray voltage in a new dairy barn.....this is a serious make or break the farm problem. This is millivolts, humans can maybe feel it with wet hands or an open cut on your hands, cows will not let their milk down and maybe eventually not enter the barn.
After losing a lot of time and money, the problem was found miles away on a bad 7200 volt neutral/ground connection.
Every pole had a "butt ground coil" on the base. These were feeding into the ground the current from the 7200 volt system.
It traveled thru the earth and as it seeking more return path.
This barn was in a very sparsely populated area, the only dairy cows for miles.
You locate the bad connection by either jumping it, if no major sparking then use a digital volt meter to look for voltage drop.
Same as checking for a bad contactor under load.

jumper

@Jamie Hall Pleased that you brought up the four wire issue. Ideally inside the building there can be two more. Two hot; two returns; a dedicated true neutral; and a ground.

JUGHNE

jumper said:

@Jamie Hall Pleased that you brought up the four wire issue. Ideally inside the building there can be two more. Two hot; two returns; a dedicated true neutral; and a ground.

So how do you define a dedicated true neutral???
That is a new term to me.

pecmsg

jumper said:

@Jamie Hall Pleased that you brought up the four wire issue. Ideally inside the building there can be two more. Two hot; two returns; a dedicated true neutral; and a ground.

2 returns?

ChrisJ

pecmsg said:

jumper said:

@Jamie Hall Pleased that you brought up the four wire issue. Ideally inside the building there can be two more. Two hot; two returns; a dedicated true neutral; and a ground.

2 returns?

Residential is connected to a transformer which has a center tap. The center tap is the neutral.

So how exactly would two returns do anything?

EBEBRATT-Ed

@JUGHNE

I don't do any farm stuff but seems to me that they talked about putting an "equipotential plane" in the farm buildings the same way it's required for some swimming pools. Can't remember if it's "code" yet or not and I am too lazy to look for my code book.

I gave up on the 2017 code book. Can't read it. They didn't want to make the book any bigger with all there ridiculous changes so they reduced the print size so you need a dam microscope to read it.

I have an old "78" code book here with nice big print. I think I should wire everything to the 78 code. If it was good back then it should be good enough now. LOL

Between the small print and the size of the book the 2017 must be 4x larger than the 78

jumper

ChrisJ said:

pecmsg said:

jumper said:

@Jamie Hall Pleased that you brought up the four wire issue. Ideally inside the building there can be two more. Two hot; two returns; a dedicated true neutral; and a ground.

2 returns?

Residential is connected to a transformer which has a center tap. The center tap is the neutral.

So how exactly would two returns do anything?

That is correct that returns & neutral lead to same place, the ground on transformer. But single return for both hots mix phases. So when you plug in an instrument that depends on third prong to provide a zero reference?

If hospitals or laboratories or warships can specify six wires to each duplex; then why not your house?