Panel Grounding vs. Lightning Rod Grounding

Code does not address lightning grounding except where lightning might harm a human. Code is about human safety. (For example, a TV ariel and lightning rods have a dedicated earth ground defined by code.) Code must be met and then exceeded for appliance protection.

Code does require earthing of everything to a common point. Code requires connections to earth ground to be less than 20 feet. And code required a dedicated earth ground - water pipe is no long sufficient for earthing. An electrician will meet code requirements. But protection means code is also exceeded.

For lightning protection, wire gauge is not important. Wire length, no splices, not inside conduit, separated from other wires, and no sharp wire bends are more critical. Code does not address these 'also' issues. IOW a ground wire from breaker box to earth must not go over the foundation and down to earth. That is too long, too many sharp bends, and not separated from other wires. Earthing must be routed through the foundation and down to earth for better surge protection. Reason why is wire impedance.

A utility demonstrates how to kludge a solution when the building was constructed wrong:

also upgrades earthing to 'exceed' what only met code.

One underlying concept is impedance. Whereas a 50' romex wire to breaker box would be well under 0.1 ohms resistance to AC electricity

- that same wire may be 120 ohm impedance to a surge. Code is mostly about wire resistance. Electronic protection requires low wire impedance which is why grounding must exceed the 1990 code. Many mistakenly assumed their panel was grounded by assuming wire "resistance". They did not grasp a more important concept - wire "impedance".

Experience without underlying knowledge teaches nothing. Experience is only educational when concepts such as wire impedance are understood. So many 'knew' grounding did nothing by forgetting to learn fundamental concepts such as wire impedance. Their 'less experience' combined with no fundamental knowledge taught them nothing.

Lightning protection is in different standards (NFPA 780.) The NEC requires the earthing system for a lightning protection system to be bonded to the power earthing system. There is also a NEC note referencing NFPA 780 that says electrical system 'grounded' metal within 6 feet of lightning protection conductors may have to be bonded to those conductors (to eliminate arcing between). Lightning protection provisions are in NFPA 780. I believe that includes requirements for power service surge protection. .

. The NEC requires the wire from phone and cable entry protectors to be max 20 feet to a common bonding point (with exceptions). (20 ft may be too long.) .

. Water service pipe (at least 10 feet metal in the earth) is required to be a grounding electrode, as it has been since 1776. A municipal metal water pipe system will have the lowest resistance to earth. Because metal water pipe may in the future be replaced with plastic the NEC also requires a =93supplemental=94 electrode. .

. A rather nutty idea.

In the event of a strong surge producing large currents to earth, the voltage of the building =91ground=92 can rise thousands of volts above =91absolute=92 earth potential. The protection is largely to keep all building wiring at the same potential.

For phone and cable wires, that means there should be a short wire from their entry protectors to the =91ground=92 at the power service. A long wire allows high voltage to develop between power and phone or cable wiring if there is a surge on phone/cable wiring. That high voltage appears at anything connected to both power and phone/cable. The NIST guru on surges, has written "the impedance of the grounding system to ' true earth' is far less important than the integrity of the bonding of the various parts of the grounding system." .

=93Preferred=94 is correct. =93Right=94 is bad. =93Wrong=94 is, amongst oth= er things, a code violation.

-- bud--

Precisely! That is why I have spoken in favor of a bonded ground system for years in this newsgroup. Thanks for the info regarding bonding the lightning arrestor system as well.

You could have probably dispensed with the thanks.

Although I'm sure that you're thinking alot about "grounding" lately, it's my guess that you'll not have time to make much use of the information.

On the other hand ....... maybe you could request interment with an 8 foot copper clad rod.

Tell them to check with me for placement of the rod.

Please indicate exactly where I said ..... don't ground a panel.

To help you out ...... the gist of my opinion is ............. in my experience, it doesn't seem to make a difference whether a panel is gounded or not. In 40 years of installing I've had both grounded and ungrounded panels damaged by lightning. Matter of fact, just had another one yesterday. Panel grounded to cold water pipe not more than

10 feet away. Damaged by lightning.

********************************************************************************

And how was the cold water pipe grounded?

I'm guessing that it went into the....well,...ground. That's the way they are run here, anyway.

**=EF=BF=BD*****

In this area, we have city water which comes into the premise along with the power lines, telephone service and cable TV wires. I tried to trace it back to the telephone pole and down the street to the plumbing NIC in order to find out, but I lost track of it amoungst all the other pipes and wires. So I finaly called the water company and they said that the end of the pipe is up in Poughkeepsie NY at a reservoir someplace.

That's about as close as I can come to an exact location.

Good point. Also, code no longer recognizes a cold water pipe ground as adequate protection.

The code (US-NEC) *requires* water pipes (10 ft min in earth) be used as a grounding electrode, as it has for a very long time.

Because water pipes may in the future be replaced with plastic, the code requires a "supplemental" electrode. Ground rods were used (generally a poor electrode).

Connections to a water pipe must now be made within 5 ft of the entrance to the building.

-- bud--

This is simply not true. For many years NEC *allowed* using the cold water pipe as a ground but it is no longer acceptable.

Ground rods were and are the preferred method in all but exceptional circumstances.

Better yet, connect to the same ground rod as the electrical service ground. BTW, while researching this in the NEC I noticed that code says not to ground communications circuits to the lightning arrestor system.

. From the National Electrical Code:

250.50 Grounding Electrode System. If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. 250.52 Grounding Electrodes. (A) Electrodes Permitted for Grounding. (1) Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more .... End quote.

Metal water pipe, if it exists at the building, *shall* be used as a grounding electrode.

Water service pipes were required to be used as a grounding electrode in the oldest NEC I have, 1968. They were not "allowed" - they were

*required*. In 1968 they would have been the *only* electrode used in most installations. They were required to be used as an electrode far before that. They are *required* to be used as an electrode today. .

. Ground rods are among the worst electrodes that are allowed. A "good" ground rod, for the NEC, has a resistance to earth of 25 ohms or less. (Generally 2 rods are installed so resistance doesn=92t have to be measured.) If you connect 120 volts to a 25 ohm ground rod you get a ground current of 5 amps. That won=92t even trip a 15A breaker.

A metal municipal water supply system has a much lower resistance to earth, typically 3 ohms, and is likely the lowest resistance to earth of any electrode available at a house.

Since about 2005 a "concrete encased electrode" (commonly called a Ufer ground) has usually been required to be installed for new construction. This is a good electrode, and has replaced the near useless ground rod as the required "supplemental" electrode.

The code requires a "supplemental" electrode for a water pipe only because a metal water service pipe may be replaced by plastic in the future. From the National Electrical Code Handbook published by the NFPA: "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." (The NEC is also published by the NFPA.) .

. As can be seen in the NEC quote above, the earth ground is a "system" generally made up of more than one electrode. Connections can be made anywhere on the "system" including the wires connecting the electrodes. .

. A lightning rod system is kept separate from the power system except:

- the lightning earthing system must be bonded to the power earthing system

- 'grounded' metal in the power system that is within 6 feet of lightning protection conductors may have to be bonded to those conductors.

-- bud--

Bud repeatedly forgets 250.53(D)(2) that says:

The cold water pipe is 250.52(A)(1). It was once sufficient as an earth ground. Today, that water pipe is no longer sufficient. Code is quite blunt about this. With or without a cold water pipe ground, the building must always have one of the other earthing electrodes defined by 250.52(A)(2) through 250.52(A)(7).

Robert L Bass is correct:

McGraw Hills "National Electrical Code Handbook" by McPartland also says Bud is wrong. A fact so important as to be published in capitals:

Just another source that says Bud is wrong.

So with all the usual wisdom of a committee, it has been decreed that miles of cold water pipe, buried 8 or 10 feet below ground level is not as good as an 8 foot rod embedded in one spot of unknown soil.

OR ..... could it just be that ........... under normal conditions,

99.99% of the time, a cold water pipe IS a good ground but .......... JUST IN CASE it isn't ..... everyone should go to the extra time, trouble and expense to install an 8 foot ground rod?

Ahhhhh yes ............ the safety zealots strike again.

Definition: Saftey Zealot. One who looks for the most remote possibility of something going wrong and then decreeing that everyone should go through the time, trouble, expense and inconvience to not allow it to happen, even though the time, trouble, expense and inconvenience and sometimes danger that is conveyed to the masses ..... is not justified by the number of incidents that occur.

Example: The safety zealots cry that a law should be passed that everyone who owns a firearm should be required to have a trigger guard engaged on the weapon whenever it is not in use.

That is ..... a law that could not be enforced. A law that would completly negate the reason that most law abiding citizens own a firearm .... self defense. A law that would not affect stupid people who leave their firearms accessable, who would not obey it anyway. Thus resulting in the time, trouble expense and inconvenience of the majority of millions of law abiding firearm owners, with no discernable difference in the end results.

However, after the law is passed, it will never be recinded. Only the law abiding citizens are left holding the bag, victims of the Safety Zealot.

A familiar pattern.

. 250.52(A)(1), water pipe, is *required* to be used as a grounding electrode in my NEC quote above.

Apparently poor w_ thinks it is significant that water pipe is not in the list in 250.53(D)(2), which are electrodes that can be used as "supplementary" electrodes for water pipe. It is obvious to anyone with a brain why water pipe is not in that list. w_'s reading of this whole NEC section is bizarre. .

. w_ doesn=92t think water pipe should be used as an electrode even though the NEC *requires* it. .

. As I wrote, the NEC didn=92t "allow" water pipe to be an electrode, it

*required* water pipe to be an electrode. For a long time it was the only electrode in almost all installations.

And water pipe is *required* to be used as an electrode today.

Robert L Bass is clearly wrong.

w_ ignores the quotation that a "supplemental" electrode is *only* required because water pipe may be replaced by plastic.

w_ ignores comments on why water pipe is the best electrode at most houses. .

. w_ is an internet nut. He arrived here because someone said "water pipe". He has posted this drivel on alt.home.repair, which covers wiring issues, many times and is always challenged by the electricians that post there (not that it does any good).

Questions for w_: =96 Is water pipe required to be used as an electrode? =96 Is a "supplementary" electrode only required because water pipe may be replaced with plastic?

-- bud--

Numerous reasons why a building only earthed by the cold water pipe is insufficiently earthed =96 no longer meets code. Robert L Bass was correct and Bud is wrong.

Numerous other reasons. For example, if a cold water pipe is the only earthing, then a plumber doing service may be shocked when servicing that pipe.

Another reason - having a known, sufficient, and reliable electrode is far more important to human safety than having a more conductive electrode. Even if the cold water pipe is a better conductor, it still is inferior to a dedicated earth ground rod because reliability is essential.

Nothing can be grounded to cold water pipes anywhere inside the structure. That grounding was once acceptable. Grounding any appliance to cold water pipes anywhere inside the building is no longer acceptable per code and for reasons provided above.

Bottom line - using a cold water pipe for earthing is insufficient according to code. Yes, a cold water pipe must be bonded to the panel at a point 5 feet from where pipe enters earth. This is important, for example, because exterior currents that might enter a building on water pipes must be bonded to breaker box so that those currents are neutralized; can not a human threat. So yes, the water pipes still must be bonded to breaker box.

But utility water pipe as the only earth ground - a complete code violation.

This is beyond and for reasons not related to the original topic. This is about human safety; not panel safety. Panel grounding requires a short connection to the single point earth ground.

*required* water pipe to be an electrode. For a long time it was the only electrode in almost all installations.

And water pipe is *required* to be used as an electrode today.

Robert L Bass is clearly wrong.

- he frequently is.

pipe". He has posted this drivel on alt.home.repair, which covers wiring issues, many times and is always challenged by the electricians that post there (not that it does any good).

When the conversation devolves from technical to personal insults it is a sure sign that the person posting insults has nothing further to offer on the subject.

Water pipe can be plastic. How does it provide earthing (as you said it always must) if pipe is plastic? Very simple. Water pipe need not be an earthing electrode.

Required: metal water pipes must be bonded to the electrical panel

- even if that earthed pipe is plastic. Bonded does not mean earthed. So that dangerous currents from outside a building do not threaten human life, pipe bonding must occur within 5 feet of earth. Water pipes are required to be bonded. Pipes are not required to be an earthing electrode.

Code is quite clear. Even if the water pipe is an earthing electrode, the building is not earthed until some other earthing electrode is installed. Code has changed. Only earthing electrode that is not sufficient is the cold water pipe.

Water pipes must be bonded to the electrical panel. Nothing says that water pipe must be an earthing electrode.

Code {250.53(D)(2)} that says this was quoted. A book on the 2005 National Electrical Code was so blunt about this as say so in CAPITAL letters:

Robert L Bass has posted accurately. Bud must ignore National Electrical Code 250.53(D)(2) to post inaccurately. Water pipes are required to be bonded and are no loner sufficient for earthing.

Again, returning to the subject: water pipe bonding does not solve panel damage which would explain why others who 'thought' the panel was grounded instead saw damage. Panel must not be grounded to water pipes. Grounding to an outside faucet, for example, is an insufficient ground per code and for lightning protection.

"Technical insults"?? Like my panel's better than yours?? My battery's bigger than yours? :-)