grounding of dss sattelite dish

[drtymex]

Well,I just had a dish installed and workmanship and installation was flawless,but,my only concern is method of grounding of the dish was an insulated #14 to a 3/8" dia. ground rod,wasn't there for the install so I can't tell you the length,and was not bonded to the grouding system of the house.

Looked under 810-21 and 820,wasn't sure if this covered dishes or is there some exception to the rule?I would think you need to bond to existing grounding system.Correct me if I'm wrong.

 

[tom baker]

Re: grounding of dss sattelite dish

810 is the article for satellite dishes, and the coax is covered by Art 820. The title of Art 810 is a bit misleading, but it does cover all recieving stations, such as a DSS.

 

[hurk27]

Re: grounding of dss sattelite dish

We have that problem around here all the time. And we have had some of those dishes hit by lightning too, that little #14 wire just vaporizes like it wasn't there matter of fact you wouldn't know it was installed but by the ends left at the dish and melted copper on the ground. that little ground rod which can most of the time be pulled right out of the ground as it's only 3' long. and the fact that there is no bond to the main service GE this is asking the lightning strike to come right into the house following the coax to the receiver to get to the house neutral/ground which will be a better ground!
It will always be better to give the lightning a better path out side the house. I still don't understand why the NEC allows for the #14 to the little ground rod but it does to me this is asking for problems in the event the dish takes a hit.
Well thats my two cents worth.

 

[drtymex]

Re: grounding of dss sattelite dish

Thx again for you replys!!

 

[hornetd]

Re: grounding of dss sattelite dish

810.21 requires that that electrode be bonded to the electrical system electrode.
--
Tom

810.21 Grounding Conductors ? Receiving Stations.
Grounding conductors shall comply with 810.21(A) through (J).
(J) Bonding of Electrodes. A bonding jumper not smaller than 6 AWG copper or equivalent shall be connected between the radio and television equipment grounding electrode and the power grounding electrode system at the building or structure served where separate electrodes are used.

 

[gwz2]

Re: grounding of dss sattelite dish

Go with ' hornetd 's post.

 

[sparky46514]

Re: grounding of dss sattelite dish

I just had DirectTV installed.Had Dishnetwork and had grounded multiswitch myself with # 12 to the ground electrode.DTV just reused # 12 but am unsure if he would have ran a ground conductor if it had not been there.Installer did not seem to be aware of code other than it was out there.

 

[satman]

Re: grounding of dss sattelite dish

Your right most DSS are not grounded to NEC, in fact the grounding of the mast is now eliminated from the instruction manual of the latest Dish Network System.

810.15 specifies that all metal antenna masts
810.21 be grounded with a #10 AWG copper. Insulation not required.

820.40 (A)(1) coax ground wire shall be insulated
820.40 (A)(4) grounding conductor shall be #14 AWG

820.40 (D) Bonding jumper required between antenna system electrodes

satman

I use #10 AWG insulated for both coax and mast.

 

[boblam]

Re: grounding of dss sattelite dish

This is a related topic. A DSS was grounded via a small wire from the multiswitch to an interior metal cold water pipe inside of the house. This caused a problem for me as it set up a ground loop between the dish and some high end stereo gear in the house. There was a noticeable hum from the stereo. Is it acceptable to remove the ground from the cold water pipe and tie it to the ground of the home's electrical system? Can I also ground the coax near the equipment through the home's electrical ground via an existing outlet? In experimenting, this solved my ground loop problem. If this isn't acceptable, what is?

 

[dereckbc]

Re: grounding of dss sattelite dish

Originally posted by boblam:
1. Is it acceptable to remove the ground from the cold water pipe and tie it to the ground of the home's electrical system?

2.Can I also ground the coax near the equipment through the home's electrical ground via an existing outlet?

3.If this isn't acceptable, what is?

1. No, the cold water pipe should already be part of the ground electrode system.

2. Yes, you may ground the coax near where the equipment is used. But to meet code you should also have it bonded to the ground electrode system where it enters the building.

3.Refer to 1 & 2. The hum you mention is quite common in A/V gear. Many people in mis-guided attempts ground the equipment that is not in compliance with code. It does solve the noise problem, but leaves an extreme risk of fire and shock danger in the event of a fault or lightning strike. There are several methods of eliminating the noise and remaining compliant with code. The problem is as you mention ground loops. The loops cause slightly different voltage potentials in the ground system where the sensitive equipment is plugged into and referenced to the electrical system. What is needed is a single point ground for all the A/V equipment, or isolation techniques. Here are some proven methods. Some expensive, and some economical.

1. $ Install a quality surge arrestor that has surge protection devices with I/O ports for your grounded signal cable (i.e. coax cable). This creates a single point ground for the AC supply and signal sources. Use the surge protector to power all the A/V equipment and reference all signal cables. There are several manufactures that supply these devices. Look for UL-1449 ratings.

2. $ Install isolation balums on grounded signal cables like coax. This will break the ground loop created by the A/V equipment power ground and coax electrode ground.

3. $$$ Similar to # 1 is to install a balanced power isolation transformer system. It contains an isolation transformer, I/O ports for signal cables, surge protection, EMI/RFI filters, and voltage regulation. Again all A/V equipment and signal cables pass through the device to create a single point ground.

4. Cheapo. Do not do anything, and live with the noise.

[ December 30, 2003, 12:08 PM: Message edited by: dereckbc ]

 

[boblam]

Re: grounding of dss sattelite dish

I agree with most of your comments.

I thought acceptable central building ground points are:

1. Grounded interior metal cold water pipe within five feet of the point where it enters the building.
2. Grounded metallic service raceway.
3. Grounded electrical service equipment enclosure.
4. Eight-foot grounding rod driven into the ground (only if bonded to the central building ground by #6 or heavier bonding wire).
5. Other acceptable grounding electrodes that comply with sections 250 and 810 of the National Electrical Code (NEC).

Wouldn't changing the ground from the waterpipe to the ground in the electrical system be the same as point 3 above?

I tried doing as you suggest and tie everything to one common ground; however, there must still be a ground loop somewhere between the water pipe and the home's electrical system ground that causes a hum in the stereo system. Thoughts?

 

[dereckbc]

Re: grounding of dss sattelite dish

boblam, any of the electrode points are acceptable.

Check to make sure the water pipe is bonded or poorly bonded to the electrical service. I have never seen a clamp that did not fail in a short period of time. You might also have some insulationg joint like through a water filter or something.

If you want to go all the way, install a dedicated branch circuit to your A/V equipment. Route all entry coaxes so the pass by the GEC for the service and bond the shields and any surge protectors to the GEC. Then at the A/V equipment install either a surge refence equalizer or isolation transformer as previously mentioned.

In my experience most A/V equipment does not use a ground, so the only ground is from outside or interconnecting coaxes. The TVSS reference equalizer should do the trick.

[ December 30, 2003, 05:45 PM: Message edited by: dereckbc ]