Grounding wire from panel to gas pipe???

[blueman]

Can you explain what this means and why it implies that it shouldn't be grounded?

Also, where would I find this tag?

[blueman]

According to your explanation, then I would think that the gas pipe SHOULD be grounded. For you say that the in-house pipe is insulated from the underground piping and hence NEITHER grounded nor "cathodic protected".

Of course the pipe may end up being indirectly grounded through an appliance ground, but that seems like all the more reason for installing a solid, secure, permanent ground connection to the panel ground. After all, what if the appliance is miswired and the appliance ground is energized resulting in the pipe being energized (yet insulated from earth ground), resulting in shock just like with a water pipe...

[blueman]

Yes, but my question remains whether to attach the gas pipe to panel ground not for the purpose of grounding the panel but for the converse purpose of ensuring that the metal pipe inside the house never gets energized.

[blueman]

The electrician installed one exterior copper rod sunk in the ground and attached directly to the 200A main breaker (which is exterior to the house in a box with the meter) and then a second copper wire running from where the water source enters the house (old galvanized

1" metal pipe) to the grounding strip within the 200A Subpanel.

Service Entrance 200A Main Breaker 200A Subpanel 100A Subpanel Neurtral----->[----------]---------->[-----------]--------->[-----------] [ | ] [ ] [ ] Earth grnd -->[--------- ]---------->[-----------]--------->[-----------] | Water pipe -----|

Note that all other subpanels feed off of the 200A Subpanel. Note I have also shown where the neutral and grounds are bonded at the main breaker.

Does this make sense and is it legal?

[blueman]

Do you need to explicitly bond the hot and cold pipes together using a copper wire jumper, or is there electrical continuity through the war heater? (Note my house is all coper pipes)

Also can I bond the gas pipe to the subpanel indirectly by just jumpering the gas water heater intake pipe to the cold water pipe entering the hot water heater?

Or is it required to directly bond the gas intake pipe at the meter to the panel ground using a single wire?

Or is all of this unnecessary since the water heater itself provides a conducting path bonding the gas pipe system to the water pipe system (and then back through the water pipe to the panel ground)

[Jeff Wisnia]

I agree with you on that providing as you say, the grounding is done on the house side of any insulated coupling.

I was responding the the "buried thus same potential" statement, and should have made mention of the what you just did, that an "extra" ground between the panel ground and the in-house gas piping can't hurt, and may even be required by code.

Jeff

[Bill]

There are two issues here. Providing a good ground for your electrical service *and* grounding metal pipes in the house to prevent them from becoming energized.

Grounding your electrical service...

In the old days when all pipes were metal, a cold water pipe ground would do. But then there were problems with rubber grommets on water meters in basements isolating the inside water piping from the outside water piping, plastic piping run outside underground, and the ground wires becoming disconnected or damaged say by a lawnmower or whatever.

So a better grounding solution was found. That is a cold water pipe ground

*and* a separate ground wire run from the electrical service panel to two ground rods placed 6 ft. apart. (double back-up) Also a ground wire which electrically connects the water pipe before the water meter to the water pipe after the water meter.

Grounding metal pipes/objects in the house to prevent them from becoming energized...

The idea of a 3rd prong on an electrical plug (ground wire) for an electrical appliance is that the metal case of the appliance is grounded. Then should there be a loose wire which touches the metal case and a person walks up and touches the metal case, the person will not be electrocuted. Or it would trip the breaker also protecting someone from being electrocuted.

Same thing with metal pipes or objects in a house. It is possible that a hot water pipe (which might be isolated because of rubber grommets) could become energized. So it is a good idea to run a ground wire from the cold water pipe to the hot water pipe (in homes with metal piping).

Hot and cold water pipes are very accessible to people. Sinks, washing machine, etc. Although gas pipes are not readily accessible to people, I suppose it wouldn't hurt anything to ground this as well. If grounding the gas pipe, I think running a ground wire from the gas pipe (house side of meter) to the ground rods or to a cold water pipe ground would be best. I don't think it would be a good idea to run a separate ground wire from the electric panel to a gas pipe.

Also while grounding things in the house, it is very important to ground metal objects around sinks and especially the bathroom. Like metal medicine cabinets which have a built in light fixture. The heat from light bulbs can cause insulation on wiring to melt away, then the metal cabinet can become energized. In a bathroom you are in bare feet and might be turning on the water while opening the medicine cabinet with the other hand - zap!

What can go wrong...

I have seen ground wires from main electrical service panels become disconnected. There could be a situation where the ground wire(s) from the main service panel become disconnected but someone ran a ground wire from there to something else like a gas pipe. Then an appliance could malfunction and this in turn could cause the gas pipe to become energized (if it was not inadvertently grounded via an appliance). So for this reason it is *not* a good idea to ground things such as this to a connection in the electrical panel, but to ground them directly to a ground such as cold water pipe and/or the ground rods.

Also you can get different "ground potentials". The ground at point A may be slightly different electrically from the ground at point B. For this reason, it is a good idea to ground everything at one point. That is run all ground wires or bond various grounds to say the ground rods or a main grounding point.

[John Hines]

No.

No, each utility does its own thing. Let the phone, and cable companies run their own grounds, to the unified ground of the electrical system.

Grounding is much less a concern to the gas company with their underground architecture than it is to the electric and phone companies with their aerial ones.

Yes, same gauge wire for all your grounding runs.

The galvanic corrosion problem mentioned refers mixing the types of materials on the pipes and wires, don't use a copper grounding clamp on an iron pipe, and vice versa.

A gas appliance, such as a furnace or range, that has an electrical hookup, will ground the gas line(s) that are connected to it, so you don't need to worry about it.

You need to "jump" over anything that is removable, such as the water meter, and the water heater, so that the plumbing is always grounded even if something is removed.

-- Silly sig to prevent isp ad

[John Grabowski]

Usually there is continuity through the water heater, however it is not an approved connection. You must use a #6 copper or #4 aluminum wire with approved water pipe ground clamps.

That is how I do it. I usually run one continuous piece of bare wire through each clamp on the hot water pipe, cold water pipe, and the gas pipe on the water heater. When the inspector comes he goes straight for the water heater and sees the bonding. If you have a hot water heating system and/or a well, those pipes need to be bonded with the others as well. Try and keep the clamps back far enough so that they will not interfere and do not have to be removed to change out the water heater.

In New Jersey the above bonding is required. Check with your local electrical inspector to learn what is required in your area.

There should also be a jumper wire from one side of your water meter to the other.

[John Grabowski]

I think that the water pipe grounding conductor should have been connected at the same point as the ground rod conductor at the main breaker in order to be code compliant.

Are the neutral conductor and the water pipe grounding conductor terminated separately so as to be isolated electrically from each other in the 200 amp subpanel?

[Randy]

The advice to check with the local inspector (AHJ "Authority Having Jurisdiction" in electrical-speak) is proably the best advice.

For those that want to read about it, EC&M (Electrical Contracting and Maintenance Magazine) has this article -

See also:

Randy

[sym]

ive found most inspectorsdo not enforce this code here and some are requiring only one ground rod we still use two but ground rods are nearly worthless,certain conditions dont matter how many you drive down you still dont get the 25 or less ohms to ground

[blueman]

Yes. That is what I was trying to show in the picture.

[Tom The Great]

Only qualified allow qualified personnel work on electrical systems, and follow all construction codes.

IMHO:

1. Required per 2005 NEC 250.104(B)
2. Required.
3. Per 250.104(b) use 250.122 as source of size.
4. Nothing special, but ensure you follow the NEC and local codes. Give your local code enforcement inspector a call.
5. 250.104(B) tells you the options you have to bonding the metal piping to. One includes bonding to the grouding electrode. If your water pipe meets the requirements of 250.52(A)(1), then it is a grounding electrode. So a water inlet piping can be used per code.

Now all this is using the NEC, and guessing about your local setup. Only a qualified person working on site can help you. So this is not a how-to, but a starting point for planning your operation. Research with your local inspector, or AHJ.

later,

tom @

[Doug Miller]

Note the word "a". Not "the".

And it flatly prohibits using it as the *only* grounding electrode.

You have things backwards. The ground rod is the *primary* grounding electrode, and the water piping is the supplemental electrode.

You're also wrong about the reason.

"Bonding of piping systems... the basic concept is to ground any metal pipes that would present a hazard if energized by an electrical circuit." [National Electrical Code Handbook, Section 250-80]

I don't know how to put it any simpler than that.

[Bud--]

The NEC has for a very long time required that water service pipes be used as a grounding electrode. The current code REQUIRES that water service pipe with metal pipe underground length of 10 ft or more be included as a grounding electrode. Because this pipe may in the future be replaced with plastic pipe, a supplemental electrode is required - usually ground rod(s). For new construction use a Ufer ground/concrete encased electrode. These electrodes are connected together to make a grounding electrode system. The earthing resistance of a metal municipal water system is lower than anything you can provide in a house.

bud--

[Bud--]

I agree. The NEC requires the water service pipe (if 10 ft or more length underground) to be connected to the ground/neutral at the service disconnect, along with the ground rod. Also connecting it to the ground bar in the subpanel is OK.

bud--

[blueman]

Well, I called our local gas company (Keyspan) and after a few handoffs, I was told that they do NOT recommend grounding the gas pipe. In fact, they say that if they see such a bridging on a service call, they typically remove it.

[Bud--]

So what? Metal water service pipes (10 ft or longer) are REQUIRED by

250.50 to be a part of the grounding electrode system. This basic requirement has been in the code for a very long time. Ground rods are not required to be installed.

So what? See reason.

You have things backwards. With a water pipe a "supplemental" electrode is required - 250.53-D-2. A "supplemental" ground rod is a strange name for the "primary" grounding electrode.

Grounding rods are 'good' if their resistance to earth is 25 ohms or less (or use 2 rods and it doesn't matter). Municipal water pipe earth resistance is typically under 3 ohms.

Grounding electrode conductors to a water pipe must be up to 3/0 copper for large services. For a ground rod they can be #6 Cu for any service. For a Ufer ground #4 Cu.

A ground rod is not required, only another electrode. A much better choice for new construction is a Ufer ground/concrete-encased electrode. Presumably the NEC language has been changed to require Ufer grounds for new construction (if there is a foundation or footing). [Are AHJs requiring Ufer?] Ufer earth resistances are likely under 5 ohms.

From the National Electrical Code Handbook - 1996 publushed by the NFPA under 250.81(a) [in 1999 this morphed into 2005-250.52-A-1] ?The requirement to supplement the metal water pipe is based on the practice of using plastic pipe for replacement when the original metal water pipe fails. This leaves the system without a grounding electrode unless a supplementary electrode is provided.?

(Note that the ground rod is a "supplementary" electrode.)

If the water service pipe is plastic and there is interior metal water pipe it is required to be bonded by 250.80. If the water service pipe is metal (10 ft...) it is REQUIRED by 250.50 to be a part of the grounding electrode system and 250.80 is irrelevant.

I don't know how to put it any simpler than that.

bud--

[Doug Miller]

"A part", yes -- but it is not permitted to be the *only* grounding electrode.

Technically true, but misleading. You may use a ground rod, a ground plate, a buried wire ring, or the metal framing of the building, as the *only* grounding electrode. But not a water pipe.

The Code permits using a ground rod, alone, as the grounding electrode. It prohibits using a water pipe, alone, as the grounding electrode. Quibbling over which is "primary" and which is "supplemental" doesn't change those facts.

Irrelevant. The Code does not permit a water pipe to be the only grounding electrode.

Again:

I'm not sure why you're having so much trouble grasping this.