Retrofit-Grounding Fifties-Era House?

[(PeteCresswell)]

I tried this in misc.rural, and got a recommendation to try it here.

------------------------------------------------------------- Been quite awhile since I started wondering what it was with the "Building Wiring Fault" lights on my UPS'.

In doing some homework prior to getting a generator transfer switch installed, it became apparent that houses need tb "Grounded" - and the typical ground is one or more copper rods pounded into the ground and then attached to a (neutral?) wire in the breaker panel.

This house is a split-level, crawl space but no basement, built in the fifties and I am unable to find anything that even looks like a ground.

One reason for no ground might be what the house is built on: a shale ridge. The builder scooped a notch out of a hillside, sold the topsoil, and built this house on the notch. Go down about 4", and you hit shale that is so solid that you need an air hammer or a breaker bar and lots of time to get through - as in 3 days with a breaker bar and a tin cup to make 2 4" wide 28" deep holes for a boat rack I put in last year.

Realistically, we've been in this house for 30+ years and never lost an appliance to electrical surge... but still... there's got tb good reasons for grounding.

That being said, I'm exploring after-the-fact methods.

The obvious is the copper pipe that water comes in on: buried several feet deep and running a good 30' to the main under the street. Seems like this was SOP until some time in recent history when it was deemed inadequate.

The second thing that comes up is a "Ufer" ground wherein the ground wire is tied to rebar in the house's foundation. I can find a lot of articles on the techniques of doing this in new construction, but nothing about retrofits.

The third approach seems tb lateral: long trenches in the yard with the grounding medium layed in the trench. Seems impractical to me bc the standard calls for 30" deep...

Has anybody been here: retrofitting a ground system to a house built on shale or rock?

[gregz]

I would want an evaluation of the current hookup from the pole. Do you have a pole ?

Greg

[(PeteCresswell)]

Per gregz:

Yes.

Could that be something the electric utility would be willing to do?

I'm thinking maybe some sort of equipment or even personnel safety concern.

[gregz]

Don't think. If it were here, I could ask local permit office for requirements. If things were changed, then power company should inspect before meter was attached.

Greg

[bob haller]

look for ground wire coming down side of pole.

there are hammer tools designed to install ground rods which are currently coper coated stell for strength

[crazy]

That's simple.

Drill a hole all the way thru the core of the earth. Eventually, the drill will exit somewhere in China. Run a copper wire all the way thru this hole, and connect the far end of the wire to the ground rod of whoever has the closest house to your hole, in China. Then connect the near end to your breaker box ground bar.

That's all there is to it!

Plus, there's MORE.....

If your house ever gets hit by lightning, some idiot in China might get electrocuted. That's the price they pay for hating Americans.

[trader4]

Have you pulled the panel cover off and looked inside? The ground wired would be inside, tied together with the neutral. This was standard practice in the 50's. In the 50's having the system grounded was already standard practice. Back then, likely they would have tied it to the water pipe. But it's also possible there is a ground wire going somewhere.

[bud--]

I assume this is the US, and there is an electrical code that is substantially the same as the National Electrical Code.

There are several major elements to the building "ground" system.

One is a bond between the neutral and service panel enclosure. The enclosure is the basic system "ground". The bond may be a visible strap. It can be a screw that just looks like a mounting screw for the neutral bar. This bonding is critical for tripping breakers when there is a short from, for instance, the hot wire in a drill to the metal drill case that is connected to the ground pin at a grounded receptacle.

Another element is one or more earthing electrodes. They are not for tripping breakers. They keep the building "ground" at approximately earth potential, and keep the hot and neutral wires at a reasonable potential with respect to earth.

The third element is grounding conductors that go with the branch circuit and connect to the ground terminal on receptacles. The grounding conductor can be a bare or green wire, or it can be the metal of the wiring system.

I would understand "building wiring fault" to mean that there is no branch circuit grounding conductor or there is no neutral-ground bond at the panel. The UPS has no way of telling if the building "ground" is earthed.

In the 50s the water pipe would have been entirely adequate as an earthing electrode. A metal water service pipe and metal municipal water system is still the best earthing electrode you will find at a house. Relatively recently a "supplemental" electrode has been required because the metal water service pipe can be replace by plastic in the future. The the N-G bonded service bar should have been connected to your water pipe (#6 wire is usually used for 100A services), and a bonding wire should have been connected across the water meter. The code now wants the wire from the panel to connect within 5 feet of where the water pipe enters the house. This will be your best earthing electrode.

This is the next best earthing electrode, but is only practical to add before the foundation is poured.

Ground rods can be driven at an angle or even installed flat. Ground rods are about the worst electrode.

Ask the electrical inspector what they would recommend.

[(PeteCresswell)]

Per bob haller:

I think I found it: 6mm solid copper coming out of the breaker box in two places. I was looking for that woven flexy stuff that appears in so many photos - and the patina made it look like an old telephone cable.

One runs through a wall, down behind a drain spout, and disappears into the garden soil next to the house.

The other runs along the ceiling, into the furnace room, and attaches to a cold water pipe.

I think I'll pursue gregZ's recommendation and find somebody who can tell me if the system is actually working (in light of the "Ground Fault" lights on various UPS'). Maybe the guy who installs the cutover switch...although I have learned the hard way that not just any electrician chosen at random is what I'd call a craftsman.... Competence I don't know enough to judge... but the appearance of some of their work makes me wonder -)

One thing I don't like is that the 6mm copper is bundled in with an RG6 TV cable and several Cat5 Ethernet cables on it's way to the water pipe. Unencumbered by any knowledge, I have to wonder if a high voltage spike grounding out along that copper might bleed over and fry whatever Ethernet or TV devices are on the ends of those cables. Or can I trust it to completely take the path of least resistance?

While looking for the elusive house ground, I noted that the TV antenna we had installed several years ago has a long ground wire, but no ground. The wire is just coiled up in the garden soil next to the house under the antenna. I guess Job#1 (after a call to the installer....) is to run that wire through the crawl space and mate it up with a cold water pipe. ??

[(PeteCresswell)]

Per [e-mail]:

Bingo for both.

They used solid copper instead the woven flexy stuff I was looking for... so it took awhile to recognize it.

In the context of the "Ground Fault" warnings from various UPS', though, I still think I need to have the ground electrically verified... I'm guessing there are tools for that and it's just a matter of finding the right person with the right tool.

[Mr.E]

Possible that the ups is looking for a device ground at the outlet and does not have continuity back to the panel. It has no way to measure the complex ground/neutral panel connection. A voltmeter can be used to verify the ground integrity at the outlet. A 25 watt test bulb will indicate if the ground has a high impedance even though shown to exist by the voltmeter. Your house ground seems to be of the older rod plus pipe standard that was prevalent when built.

[trader4]

The UPS would have no way of knowing if there is an actual earth ground of not. It could have a way of knowing if the outlet ground is connected to the neutral, but that's it.

There are two issues. One is if the panel has an earth ground, which you have now verified. The other is if the grounds from outlets are in fact connected back to the panel ground. If you're having problems with UPS faults about ground, I would suspect that the outlet does not have a ground path back to the panel.

[gregz]

Best to separate things as much as possible. all my incoming is all in one place, but the wire to the water ground is 35 feet away.

Antenna ground should be far away as possible from other things, including your house.

Greg

[trader4]

Says who? Typically an antenna is installed on the roof of the house and the ground is run to the single point grounding system for the house. Where should they run it to? Afghanistan?

[.-.]

Great discussion and useful information. It wasn't a retrofit, but I do have thick layers of sandstone about 18 in. below grade (no basement!) and so made sure that the water and gas piping in the house, now about 10 years old, is bonded to the copper water supply pipe going to the street. The gas supply pipe is plastic. The water pipe is buried in a trench about 3 feet deep chipped out of the rock and back filled with sand and top soil.

The main panel is connected to a ground electrode which the contractor made by drilling down into the stone and putting in a copper rod. I've checked for a voltage difference a few times between the panel and the incoming copper water pipe and it measured zero on the most sensitive setting of the multi-meter. Probably that's because the top soil is usually moist to wet since rain water doesn't sink into the sandstone, but slowly moves horizontally keeping the region around the top soil and stone conductive.

The incoming water pipe and ground electrode are about 15 feet apart with no direct bond. Should there be one?

Tomsic

[bud--]

I agree. There should also be a ground block where the coax enters the house. That allows the coax shield to be earthed. That connection, in particular, plus the ground wire from the TV antenna, should connect to the earthing system near the service panel. During a surge "event" (or a near lightning strike) the "ground" at the service panel may be thousands of volts different from 'absolute' earth potential. Much of the protection is that all wiring in the house - power/TV antenna/cable/phone/... - rises together. That requires a short wire from entry protectors to a common connection point on the earthing system. The distance from the service N-G bond to the common connection point also has to be short.

[bud--]

Some gas utilities don't want their gas pipes bonded to the electrical. With a plastic supply it shouldn't matter. The way the NEC handles it is that metal gas pipe is connected to the building ground at appliances, like gas stoves and furnaces.

Zero voltage means there is little, if any, current to earth (shouldn't be much anyway).

Not obvious if it is from the description, but the water pipe should also be used as an earthing electrode. Water pipe and ground rod should both connect to the service panel neutral-ground bar. They can connect at the bar, or (if I remember right) the ground rod wire can connect to the water pipe wire at a convenient point. There should be a bond wire across the water meter.

My guess is that the resistance to earth is quite high. In a surge "event" the building "ground" will lift higher above 'absolute' earth potential than usual. Having short ground wires from entry protectors (phone, cable, dish, ...) to a common connection point on the earthing system is more important than most houses. And the distance from the service N-G bond to the common connection point should also be short. You want all wiring to rise together.

[bob haller]

YES!!!! and the water meter should have a jumper, since meters can be poor conductors and mayy be removed at some time

[(PeteCresswell)]

Per bud--:

Is there a conflict there for a TV antenna mounted on the North end of the house with coax running down the North wall and entering the crawl space there - and a service panel on the opposite end of the house?

[trader4]

In that situation the technically correct thing to do would be to have another ground rod on the end of the house with the antenna and have that ground rod bonded to the ground rod at the main panel. However there are plenty of houses out there that just have the antenna ground on one end and the panel grounded on the other. This common ground is one reason utilities, ie electric, phone, cable, etc come in at the same place.