To remove dangerous voltage on metal parts from a ground fault, electrically conductive metal water piping systems, metal sprinkler piping, metal gas piping, and other metal piping systems, as well as exposed structural steel members """""""that are likely to become energized"""""""", must be bonded to an effective ground-fault current path [250.4(A)(4)]. Although bonding isn?t required for isolated sections of metal water piping connected to a nonmetallic water piping system, metal water piping systems must be bonded in accordance with the following:
My house is about 40 years old. I just took a hit on my computer equipment. I think it is because the CATV is bonded to my cold water pipe. I don't think the copper pipe is grounded.
My water heater is gas so it is unlikely to become energized. Is the copper pipe in my basement required to be grounded?
Can I make the CATV guys ground their equipment to my service mast as my grounding electrode is likely buried on an inside wall that is covered with sheet rock and a concrete floor?
Your internal copper water pipe, except small isolated sections, should be bonded to the grounding electrode system, which in your case is going to be one or two driven ground rods connected to the neutral/ground bar of your main service panel.
The CATV guys will ground their equipment to anything they can find that's grounded
The thing I am pondering now it that I have a dead modem, dead router, and 2 dead motherboards.
I would like to be able to pin it on the CATV guys as it almost had to come in on the CATV as I have a UPS and both computer power supplies are good. The only thing that was not connected to the surge suppressor were the Cat 5s going to the network cards. That was an over site on my part as the UPS does have network jacks.
I agree with you that the piping "should" be grounded. I want to know if it "has" to be grounded.
I think it was you that posted a link to the NEC online once. Do you still have that link? I saved the link, but the computer is not working at the moment. :)
As always, thanks for you suggesti>Your internal copper water pipe, except small isolated sections, should be
Originally your water pipe was required to be used as a grounding electrode and connected to the power system ground. That connection now has to be within 5' of the entrance of the water pipe to the house. Your house is old enough the connection could have been anywhere.
With the PVC water service you now have, the interior metal water pipe has to be bonded to the electrical system ground with similar rules, but the connection no longer has to be within 5' of the entrance. Bonding requirements are in 250.104-A.
If the water pipe is not connected to the power system ground it is not the CATV guy?s problem.
--------- The requirements for grounding electrode for CATV are in 820.100-B. (They are about the same for phone.)
The only point on water pipe that can be used for the CATV ground is the first 5 feet inside the house. (This may have been different in the past.)
Your metal electric service mast is another permissible grounding point.
(In recent versions of the code, there has to be an accessible point provided to connect the CATV, phone, ... ground to.)
The grounding conductor from the CATV entry block has to be 20' or less, (or a ground rod has to be added and the CATV block still has to connect to the power grounding system). But the connection from the CATV entry block to the earthing wire at the power service should be as short as possible as I said under single point ground in your previous thread.
--------- You don?t describe your computer setup. If you have widely separated computers, each connected to its own suppressor, and interconnected by ethernet, a surge can shift the ground potential at one end resulting in a high voltage between computer and ethernet cable at both ends.
As I said in your previous thread, when using a plug-in suppressor all interconnected equipment needs to be connected to the same plug-in suppressor, or interconnecting wires need to go through the suppressor. And external connections, like ethernet, phone, CATV also need to go through the suppressor . Connecting all wiring through the suppressor prevents damaging voltages between power and signal wires. A UPS can act as a plug-in suppressor.
If *all* equipment was connected to the same suppressor, the ethernet cables wouldn?t have to go through the UPS.
Another question is what are the surge protection ratings of the suppressor/UPS.
Originally my house was supplied by a well. The house has a partial basement and a crawl space. The well is located in the crawl space. The first drop from the well is to the clothes washer. (This could actually be the grounded part if the pipes are indeed grounded. The panel is located on an inside wall in the washer/dryer room. That part has a poured slab floor) My health is not good, so crawling under the house is a big deal. I did take a flashlight and look. None of the copper pipe is even in contact with the earth although I would not have been able to see a ground clamp if there was one.
Would it not be the CATV guy's problem if the pipes were PVC? Everyone now a days uses PCV for repairs. I pay $100 a month for Internet/Cable. I think I would be justified in asking them to come back out and ground their system to the service mast. I am still considering asking them to pay for my computer repairs.
The two computers that were damaged were setting within 3 ft of each other. There were actually 3 all plugged into the same place. The cheapest one that I had built from spare parts didn't get damaged.
All 3 computers were plugged into the same UPS (1500va). The router, modem, speakers and monitor were also plugged into the UPS. One of the computers that took a hit was plugged into the surge suppressor only jack (No battery backup) The other one that took a hit was on battery. (I only have one monitor. I use a KVM switch)
The thing that is most puzzling to me is what was damaged. Changing the modem fixed my Internet connectively problem. I also have a wireless laptop. The laptop could still talk to the good computer, but neither computer could access the Internet. Changing router allowed them to talk to the Internet.
This causes a question. Why would the LAN card still be good in one computer and take out two others plugged into the same router? For this to happen, the hit would have to enter in the cable modem. It then would have had to continue on the CAT 5 cable. Then through the router to fry 2 out of 3 motherboards.
The power supplies in all 3 computers are good.
All the equipment was connected to the same suppressor.
I had almost the same blowup; the cable modem, router and motherboard .... plus my scanner got it too. My cable was grounded at the NE corner of the building to a ground rod, which the cable company put in many years ago. The current thinking is to ground the cable to the electric meter. My electric meter is at the other end of the building wrapped around by a deck. So, I called Comcast and ask that they come out to properly ground my cable service. Before they came, I pulled up a few key boards on the decking and added a couple of pull wires from the area of the electric meter, to the outside edges of the deck. When the tech came, he said, "well, I was going to tell you that I'd have to reschedule, due to the large amount of work, but you did it all, so I'll do it!" They ran a new drop to the pedestal, added a cable box next to the electric meter and ground it all to the electric meter. LOL, shortly after I canceled my cable modem as fast DSL was available and, in a few weeks I will be canceling Comcast in favor of Dish.
If I were the cable company, and if you had interior metal water pipes, I would argue that the NEC (if it is enforced in your area) requires the water pipe to be either bonded (pvc water service) or connected as a grounding electrode (10' underground metal water service). In either case I (the cable company) would argue that I connected the cable to a permissible electrode (assuming they did) and that it was not my responsibility to verify that all water pipes are connected to the electric service properly. Of course you could try asking them to pay.
If the CATV drop is near the power service, I suspect they would move the grounding point to the metal service mast.
Sounds like a good possibility. I don't remember you wrote the CATV lead went through the UPS/suppressor.
Particularly if there is *no* bonding between CATV entry and power service to shunt some of the surge, that could result in a surge too large for the suppressor (which may now be damaged).
For damage you need a difference in the voltage between power and CATV. Particularly with no interbonding that could also result from a surge on the power lines. And if the electric service is not earthed at the house the possibilities grow.
First you should ensure that your electrical system is properly grounded, otherwise moving the cable ground connection to the mast or any other part that should be grounded but may not be grounded, could provide no protection at all. After all your copper water pipe should have been grounded but wasn't. All metal parts of the building operating system should be grounded, it is your job to ensure that they are grounded by what is considered an acceptable ground according to your local electrical code and/or the NEC. For this reason I don't think you will have much success with a claim against the cable company.
Well this is still my question. What if some of the piping gets replaced with PVC? It happens all the time. I see no reason to have to rely on the copper in the basement as a grounding path. The CATV should be bonded to the service mast.
Terry That is why the US NEC forbids piping that is further than five feet away from were the piping comes out of the earth being used as a Grounding Electrode. If the cable installer connected to the water piping at any greater distance then the installation was in violation of the National Electric Code.
A point about code changes in the past 40 years: pipes installed by a plumber should not achieve electrical code grounding requirements. Electrical code wants its own earthing and wants its own dedicated bonding. Meanwhile, electrical code still demands that piping be bonded - so that pipes do not become energized and become human safety problems. That electrical source could be either inside the house or via city pipes. Either way, that electrical danger is made irrelevant when bonded to AC electrical box ground. All this grounding defined only for human safety.
Your question is not about human safety. Your question is about transistor safety. That means earthing must exceed what code requires. For example, if cable was 'grounded' by a water pipe, well, was it earthed? Even that pipe length can mean grounding but not earthing. Sharp bends and solder joints are more reason why lightning will also take other, destructive, paths into the house.
That is your problem. Lighting surge was permitted inside the house where protection inside numerous appliances was then overwhelmed.
How could NICs and router be damaged? A similar example. Lightning struck AC electric. Surge protectors adjacent to two computers simply connected that surge from black 'hot' wire to many other wires into each powered off computer. Surge was shunted from black wire to green wire and through network card on two computers. Surge traveled via network into a third computer's NIC card. Through motherboard ground, out modem, and to earth via phone line. Semiconductors in network cards and modem replaced to restore entire system AND to trace that surge.
Surge entered via the most common entry wire - AC electric. Surge found a path to earth ground via phone line. Phone line appliance was damaged by a surge that entered on AC electric. Surge was shunted into two powered off computers to find earth ground, destructively via a third. Surge that was not earthed before entering a building will find too many destructive paths. Fix one, and the surge will find another. Solution is always to earth that surge before it enters a building.
A surge need only overwhelm protection in one location to then become a good conductor to earth. One damaged computer may simply act as a surge protector; destructively protecting other electronics. That destroyed component made a better path to earth so that a surge did not overwhelm protection inside other components.
Once a surge is permitted inside the building, then solutions become too complex. Fix one potential surge problem, and the next surge will find another destructive path through another appliance. A surge must be earthed before it can even enter the building so that protection inside all electronics is not overwhelmed.
Water pipes are typically bad grounds for transistor safety. Pipes are too long, too many 90 degree bends, solder joints, etc. Most important - each incoming wire must make a dedicated connection of 'less than 10 feet' to the same earthing electrode. How those connections are installed is as critical as electrode resistance - short, no bends, no splices, separated from all other non-earthing wires, all earthing wires are independent until all meet at the earthing electrode, etc. A summary was posted in comp.sys.mac.comm on
4 Jul 2007 entitled "DSL speed" at
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Pipes are traditionally poor earthing connections. This made worse when the incoming pipe is not within a 'less than 10 foot' connection of breaker box and telco provided surge protector. Discussed is the difference between grounding for human safety verse earthing for transistor safety. Protection means a surge must be earthed before it can enter a building. CATV must make a short connection to same electrode that all other utilities also make that short connection to. Grounding to pipes (not to be confused with bonding) is not acceptable as it was 40 years ago.
Meanwhlle above only defines secondary protection. Your modem, network, etc protection also means the prmary protection system must be inspected:
Ask the cable company to move the ground to the mast. Make sure your electric service is grounded - may require adding 2 ground rods. Make sure the water pipes are bonded.
For reliable information on surges and surge protection see the IEEE at:
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the NIST guide at:
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The NEC requires now, as it has required for a very long time, that a metal underground water service pipe, 10 feet or longer underground, be used as a grounding electrode for an electrical service. Bonding can use a little different methods and is required when the service pipe is less than 10 foot metal underground.
When used as shown in the IEEE and NIST guides, and manufacturers literature, plug-in surge suppressors protect connected equipment. Protected equipment is all connected to the same suppressor or external wires, including phone, CATV, go through the suppressor.
Both guides recognize earthing, single point ground, service panel suppressors and plug-in suppressors. If you don?t have a single point ground a service panel suppressor does not always protect.
The point of a ?single point ground? is that ground wires from phone, CATV, ... protectors connect with short wires to the earthing wire at the power service. If there is a strong surge the ?ground? at the house will lift from ?absolute? ground. The whole point is that the ?grounds? for the power, phone, CATV, ... lift together. Francois Martzloff, who wrote the NIST guide, 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."
While you are at it, read the responses.
Urban metal underground water supply systems have very low resistances to ground. More limited systems are likely to be a lot better than ground rods, the likely electrode that Terry will use. A ?good? ground rod for the NEC is a 25 ohms to ground ? very poor. Usually 2 rods are used and the resistance doesn?t have to be measured.
Starting with the 2005 NEC a Ufer ground/concrete encased electrode is also required for new construction with concrete foundations. Ufer is also a good ground and makes a good ?supplemental? electrode.
Connection to metal water pipes has for quite a while been required to be within 5 feet of the entrance to the building.
The short connection is to the earthing wire at the power service.
The only change has been the requirement to add a ?supplemental? electrode in the case that the metal water service pipe was replaced by plastic, as happened to Terry.
As is well known to some on this newsgroup, w_ has some bizarre ideas.
Surge danger means that all incoming utilities must be earthed to the same electrode. Just another reasons why all utilities should enter the building at a common point - the service entrance. Each utility makes a 'less than 10 foot' connection (beyond what code calls for) for surge protection.
Meanwhile code also recommends all utilities be earthed to same earthing electrode. Exception is only when it is not practicable. But another utility offers this 'buried wire' solution to providing a single point earth ground that will also provide better surge protection:
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Essential is that every utility be earthed to a common point for numerous reasons.
Ideally you want a "single point ground" with the entry protectors for CATV, phone, ... connected with a short wire to the earth electrode at the power service. When the 'ground' at the house lifts from 'absolute' ground with a large surge you want 'grounds' for phone, CATV. power to lift together. Would the mast do that? Probably. Much better than the water pipe unless there is a comparably short connection to the earth electrode wire at the power service.
I have never seen a source that says an external buried wire between phone NID and CATV entry and power service 'ground' will keep the 'ground' potential the same at all three - the basis of a "single point ground". A ground rod is also required at the CATV entry.
Bud routinely forgets to see things that would expose his plug-in protector as ineffective.
Earthing must accomplish two task - equipotential and conductivity. To achieve equipotential beneath a building, then all earthing must be 'single point'. Some facilities only use an earth ground rod. Some install earthing as demonstrated in
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Others use far more serious earthing just to achieve a little better earth ground (ie Ufer grounds). Some examples from those who want effective protection rather than expensive 'magic boxes':
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Curious how they understood a well proven technology that Bud has never heard of. They are installing protection. Bud is promoting grossly overpriced plug-in protectors that have no dedicated earthing.
My post, was about earthing, not plug-in suppressors.
Repeats what w_ previously posted without explaining how the external wire provides a ?single point ground? - as challenged in the quote at the top.
In the US, Ufer (concrete encased electrode) grounds are required for new construction with footings or foundations. They are actually a good grounding electrode. Far better that ground rods.
Terry could install a Ufer ground. All he would have to do is tear out about 20 feet of his basement wall and footing and reinstall it. Is that what you are suggesting.
And nobody is talking about a ?magic box?. Since you insist on dragging in plug?in suppressors, the IEEE guide says that if you do not have a single point ground "the only effective way of protecting the equipment is to use a multiport protector."
If w_ was not a troll he would admit Ufer grounds have been in many of my posts.
The troll?s favorite topic again.
For reliable information on surges and surge protection see the IEEE guide at:
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the NIST guide at:
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The IEEE guide explains plug-in suppressors work by CLAMPING the voltage on all wires (signal and power) to the common ground at the suppressor. Plug-in suppressors do not work primarily by earthing The guide explains earthing occurs elsewhere. (Read the guide starting pdf page 40).
Both guides say plug-in suppressors are effective.
w_ has never found a link that says plug-in suppressors are not effective.
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