I have ground wires attached to copper plumbing on the house side of the dielectric coupling. The telephone service box has a ground wire which I found attached to copper plumbing. The satellite dish also has a ground wire which I found attached in a similar manner. Shouldn't they be grounded as best as possible to earth? In other words, shouldn't they be attached to the water service line on the dirt side of the dielectric?

Maybe it doesn't really matter and the data equipment just needs a big electron sink to dampen some kind of electrical noise. But I kind of think it's a safety issue. In the event of a lightning strike on the dish/telephone line I would think you'd want an uninterrupted conduction path to the earth.

I looked around for an installed ground rod but either this house doesn't have one or it's inaccessible.

4 Answers 4


National Electrical Code 2014

Chapter 8 Communications Systems

Article 800 Communications Circuits

IV. Grounding Methods

800.100 Cable and Primary Protector Grounding.

(B) Electrode. The grounding conductor shall be connected in accordance with 800.100(B)(1), (B)(2), or (B)(3).

(1) In Buildings or Structures with an Intersystem Bonding Termination. If the building or structure served has an intersystem bonding termination as required by 250.94, the grounding conductor shall be connected to the intersystem bonding termination.

(2) In Buildings or Structures with Grounding Means. If the building or structure served has no intersystem bonding termination, the grounding conductor shall be connected to the nearest accessible location on the following:

(1) The building or structure grounding electrode system as covered in 250.50
(2) The grounded interior metal water piping system, within 1.5 m (5 ft) from its point of entrance to the building, as covered in 250.52
(3) The power service accessible means external to enclosures as covered in 250.94
(4) The nonflexible metallic power service raceway
(5) The service equipment enclosure
(6) The grounding electrode conductor or the grounding electrode conductor metal enclosure
(7) The grounding conductor or the grounding electrode of a building or structure disconnecting means that is grounded to an electrode as covered in 250.32

(3) In Buildings or Structures Without Intersystem Bonding Termination or Grounding Means. If the building or structure served has no intersystem bonding termination or grounding means, as described in 800.100(B)(2), the grounding conductor shall be connected to either of the following:

(1) To any one of the individual electrodes described in 250.52(A)(1), (A)(2), (A)(3), or (A)(4)
(2) If the building or structure served has no intersystem bonding termination or has no grounding means, as described in 800.100(B)(2) or (B)(3)(1), to any one of the individual electrodes described in 250.52(A)(7), and (A)(8) or to a ground rod or pipe not less than 1.5 m (5 ft) in length and 12.7 mm (1/2 in.) in diameter, driven, where practicable, into permanently damp earth and separated from lightning conductors as covered in 800.53 and at least 1.8 m (6 ft) from electrodes of other systems. Steam or hot water pipes or air terminal conductors (lightning-rod conductors) shall not be employed as electrodes for protectors.


An Intersystem Bonding Termination can be either a set of terminals securely mounted and electrically connected to the meter enclosure, a bonding bar near the service equipment enclosure, or a bonding bar near the grounding electrode. These terminals are specifically for bonding and grounding of communications and other "intersystem" circuits.

If this exists, the telephone and dish should be bonded using these terminals.


If an Intersystem bonding termination does not exist, this section provides a list of acceptable alternatives. Included in the list is the "interior metal water piping system". Which can be used as long as the connection is within 5' (1.5 m) of the point of entrance, and the piping is in direct contact with the earth for 10' (3 m) or more (250.52(A)(1)).


This section gives even more alternative bonding locations, and again points to 250.52(A)(1) Metal Underground Water Pipe..


Bonding to the water piping system may not be a problem, as long as the termination is within the first 5' of the pipe entering the building and the pipe is in direct contact with the earth for 10'. However, if the dielectric union is not conductive, there should be an appropriately sized bonding jumper connecting the two sections of pipe.

If you're worried about it, or you're having problems. You could move the bonding terminations to the other side of the dielectric union, use an alternate bonding method, or install an intersystem bonding termination and use that.

  • I'm pretty sure that a bonding jumper across a dielectric union defeats the purpose of the dielectric union. (Ion transport can occur in the slightly acidic water and electron transport is facilitated by the jumper. Galvanic corrosion should occur.) Yet many municipality allow or require the jumper! Something is amiss. Much debate about it online.
    – Paul
    Aug 6, 2014 at 4:49

Bonding to a metallic water pipe system is pretty common for satellite and telephone systems. While this may not be the best choice for termination, if the grounding system is correctly installed, it will work just fine.

The NEC (and Article 250 applies to all grounding systems, while 800 only has additional requirements) requires an electrical bond to the water pipe system in addition to at least one other electrode and all electrodes are required to be bonded together to make a single grounding electrode system.

It is important to understand that electrical circuit ground wire (equipment ground) should not normally carry current. The purpose of the equipment ground is to carry fault current safely back to the ground bus on the panel, which is bonded to the neutral at the service panel. Shorts do not go into the ground, they go back to the source.

Grounding electrode conductors tie the electrical system to a local ground reference which establishes "zero volts" as the potential you are standing on. It also helps to dampen transient voltages and lightning, though it would not help much for a close strike.

Driving a separate ground is both dangerous and ineffective. This notion has been around in the electronics community for decades and is based in the wrong assumption that faults go into the ground. The reality is that by doing this you are depending on the earth to carry enough current to trip the breaker and clear the fault -- which will pretty much never happen. the recommended practice for electronics is to run an isolated ground receptacle which ties directly to the panel ground rather than being tied to the numerous other ground wires in the building.


Yes, the ground is a safety and it doesn't do much good on the house side of the dielectric. That said, most cable/dish installers will just connect their ground anywhere they are allowed to connect the ground. And most will never actually verify it is actually grounded. If the electrical panel is not too far away, move the ground connections there. If that is not an option, use a grounding stake or connect to the service side of the pipes.

  • Are you sure that it's okay to attach these grounds to the electric panel? This does not sound like it will meet NEC.
    – Edwin
    Aug 4, 2014 at 16:52
  • Why not ground alongside of the location the electrical panel is grounded to?
    – bib
    Aug 4, 2014 at 18:54
  • I mean attaching the ground wires to the body of the panel. In southern California and in the one location on the east coast where I live, this was acceptable practice for grounding data lines.
    – diceless
    Aug 4, 2014 at 20:55

If you can avoid, never ground anything, especially electronic equipment to a water pipe. There are three main reasons for this (and bunch of lesser reasons):

(1) If lightning strikes near you and it contacts the water main (like on a bridge or water soaked ground) it will fryolate anything you have grounded to the water main.

(2) Since everyone else is connecting their house supply to the water line, it means there will be a strong 60 Hz hum on the line which will vibrate anything you attach to it at 60 Hz, speakers, anything.

(3) Every bit of junk noise from every piece of badly isolated piece of equipment in your neighborhood (think Tvs, old VCRs, etc etc etc) will come in on that water line and infect all your equipment.

The optimal solution is to sink your own ground. Of course, that takes time, money and effort, but if you want well-grounded, noiseless equipment that is what to do.

  • Water main on our street is HDPE. Besides, the ground I am talking about is the Primary Protector ground which (as I have learned since asking this question) doesn't connect to the neutral of any electronics. It simply is a safety for overcurrent/voltage conditions that might occur on the lines outside the home (under the "Protection" heading: ecmweb.com/code-basics/article-800-communications-circuits )
    – Paul
    Aug 6, 2014 at 4:07
  • You said you were thinking of attaching to the water service. If you do that, you can say goodbye to anything connected to the "water service" in the event of nearby lightning strike. Aug 6, 2014 at 9:39
  • I said it is attached to the water service. I don't see the difference between a few feet of copper service line and a few feet of copper ground rod when it comes to lightning protection. Can you enlighten me?
    – Paul
    Aug 6, 2014 at 13:36
  • A grounding rod will not be affected unless the lightning hits your property directly. A strike on anything connected to the water service will have an effect even at a long distance, even thousands of yards away from your property. Aug 6, 2014 at 14:57
  • Our street main is non-conductive HDPE pipe. So this is not an issue for me, correct?
    – Paul
    Aug 6, 2014 at 15:57

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