Last November I had DirecTV install a satellite dish at my house. They ran a ground from the dish about 80' to an outside plumbing bib. It is a single wire (green insulation) and looks to be about an 8 gage or so. It has at least three 90 degree turns in it.
In the past 2 months I have had two pin hole leaks develop in my cold water copper plumbing within 5' of the water bib.
I am receiving contradictory responses on the alt.construction site as to whether this is a permissible grounding situation under the NEC and also as to whether this might have caused the problems with the piping.
I've googled and not found anything directly relating to this issue.
Can someone provide me the NEC codes for this? Any comments as to the potential for the problem being caused by the grounding would be greatly appreciated.
I cannot comment authoritatively on the connection being the cause of the pin hole leaks. I can tell you that unless that hose bib is within five pipe line feet of ware the metal pipe line enters the home then the installation was and is a violation of the US NEC. The applicable language of the US NEC is:
810.21 Grounding Conductors ? Receiving Stations. Grounding conductors shall comply with 810.21(A) through (J). (A) Material. The grounding conductor shall be of copper, aluminum, copper-clad steel, bronze, or similar corrosion-resistant material. Aluminum or copper-clad aluminum grounding conductors shall not be used where in direct contact with masonry or the earth or where subject to corrosive conditions. Where used outside, aluminum or copper-clad aluminum shall not be installed within 450 mm (18 in.) of the earth. (B) Insulation. Insulation on grounding conductors shall not be required. (C) Supports. The grounding conductors shall be securely fastened in place and shall be permitted to be directly attached to the surface wired over without the use of insulating supports. Exception: Where proper support cannot be provided, the size of the grounding conductors shall be increased proportionately. (D) Mechanical Protection. The grounding conductor shall be protected where exposed to physical damage, or the size of the grounding conductors shall be increased proportionately to compensate for the lack of protection. Where the grounding conductor is run in a metal raceway, both ends of the raceway shall be bonded to the grounding conductor or to the same terminal or electrode to which the grounding conductor is connected. (E) Run in Straight Line. The grounding conductor for an antenna mast or antenna discharge unit shall be run in as straight a line as practicable from the mast or discharge unit to the grounding electrode. (F) Electrode. The grounding conductor shall be connected as follows: (1) To the nearest accessible location on the following: a. The building or structure grounding electrode system as covered in
250.50 b. The grounded interior metal water piping systems, within 1.52 m (5 ft) from its point of entrance to the building, as covered in 250.52
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 (including any metal well casing effectively bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductors. Interior metal water piping located more than 1.52 m (5 ft) from the point of entrance to the building shall not be used as a part of the grounding electrode system or as a conductor to interconnect electrodes that are part of the grounding electrode system.
Take special note of the last sentence of 250.52(A)(1).
If you can obtain the use of a clamp on current meter, that has a valid certificate of calibration that is traceable to a National Institute of Standards and Technology (NIST)source, to see if there is current flowing in the satellite antenna's Grounding Electrode Conductor (EGC) then you will have strong evidence of the satellite TV installers culpability in your pin hole leak problem. A reading from a a similarly certified direct measuring multimeter connected in line would be evidence that would be hard to refute. The use of a similarly certified meter shunt would also suffice. Unlike a clamp on meter you will have to break the line to measure if you use either of these last two techniques. I would think it most unwise to alter the installation in any way until the necessary evidence is in hand in an unimpeachable form. The testing should be witnessed by the localities electrical inspector if they are willing to do so. If not then have the measurements done by a licensed master electrician or a third party testing company.
Do you have the ability to measure current and voltage in small quantities? I doubt that the installer used 8 awg. I have a DTV dish and they ran the #12 goofy green wire ( all humor intended ) to my electrical service riser, right next to the Telco ground.
It is "possible" that this new connection has created a new path for some current/voltage.
Is your water pipe bonded to your service? Might be where the water comes into the house or at the water heater. Has someone installed plastic pipe in the water system?
Might be time to consult with some local professionals
Generally speaking, the purpose of grounding these dishes is to dissipate a lightning strike so it doesn't get into your house and melt things or start a fire.
But if they have three 90 degree bends in the thing, it is functionally useless. If you have taken a lightning strike, you will see a hole in the insulation at the location of one of the 90 degree bends - likely the top one, but maybe the lower - I forget whether the greatest differential to earth is critical here, or whether the first bend on the way to earth potential.
If your insulation is intact, I'd change it so it ran as straight and as direct to your earth connection - and I think I'd put a 10' rod at the point where the insulation would go to ground if you dropped it. Also, if your insulation is intact it is unlikely that this conductor caused your problems with the copper wire plumbing. It may have something to do with metallurgy - is there something here maybe that is not copper, and the copper may be sacrificing itself to a less noble metal?
You're definitely on the right track here. Install a ground rod as straight and near as you can to the dish, then bond that ground rod to the service ground electrode. According to NEC you need a #6 between the two, even if the equipment grounding conductor for the dish is smaller.
Thank you. It is within the 5' of where the pipe enters our slab. However, there is only about 1' of copper pipe in the ground then it transitions to pvc which runs to our well about 150' away. So there is very little copper in the ground.
As I read:
250.52 Grounding Electrodes.
(1) Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more (including any metal well casing effectively bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductors. Interior metal water piping located more than 1.52 m (5 ft) from the point of entrance to the building shall not be used as a part of the grounding electrode system or as a conductor to interconnect electrodes that are part of the grounding electrode system.
the lack of copper pipe in the ground is in violation of the NEC code, correct?
Yes Garry that's right. Since the underground water piping is non metallic that hose bib was not a permissible point to terminate a Grounding Electrode Conductor. Were is the point that is directly below the dish on the side of the house in relation to the electric meter and/or the homes service equipment?
-- Tom Horne
Well we aren't no thin blue heroes and yet we aren't no blackguards to. We're just working men and woman most remarkable like you.
UL96A is the standard for lightning protection. You can install 90 degree bends as long as they are of a large radius. (radius is dependant on the conductor size). Down leads and conductor for all of the lightning protection systems I have installed were braded wire either of copper or aluminum not building wire.
Lightning protection is sacrificial at best. I can will all assurity guarantee you that if lightning hits the dish your going to have a LOT more problems than just a toasted dish. I worked on a home that was struck in the corner. We ended up removing all of the drywall to get at the studs so we could pull new wiring. Not one piece of wire survived end to end. There was not one electrical device in the home that was plugged in, that survived. Electrically it was total devastation. There was a UL listed lightning protection system on the roof. There were black marks down the house where the conductors were.
I beg to disagree. The function of the ground conductor on a satellite dish is for lightning protection.
And a large radius bend on a house? Where did you plan to put the conductor - and how many home owners would let you string an ugly green cable all over their homes, would ya think?
I stand by my original comments. Make the conductor straight. Sorry.
Tom, the meter is on the utility pole about 140 ft from the house. The electric service from the pole to the house is underground and comes up through the slab in the garage to a 220 CB box which then goes to a 110 CB box. ie. all 220 is fed from one CB box and all 110 is fed from another about
15 feet away (also in the garage).
The dish is mounted to a chimney which is the "middle" (give or take a little) of the roof so there is no direct path without crossing the roof. It is at least 50 ft from the 220 and 110 boxes I mentioned above.
The Grounding Electrode Conductor (GEC) for the satellite dish has to end up at the 220 panel, which is the building disconnecting means; or at one of the electrodes that make up the houses grounding system. If it is not practical to run it's GEC to the 220 panel or a grounding electrode than you run it to a new separate grounding electrode which you then bond to the other grounding electrodes to make it part of the grounding electrode system.
Thanks Tom, Sounds like its time to get a licensed Electrician to look at the entire mess. The plumbing problems have already cost me over $1500 in repairs for the two pipes. Probably won't get anywhere with DirecTV or the local company that installed it, but think I'll try anyway.
Maybe if I make a big enough noise about it (local "investigative reporters" come to mind) they won't be able to continue to get away with it.
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