Grounding a quad LNB

[mrmoose2003]

I'm replacing a dual LNB on a Dish 500 system with a quad LNB.

The SW21s both have grounding posts on the sides of the switch boxes that are connected to a grounding rod right next to the dish. I don't see anyplace on my new quad LNB that would be handy to attach a ground, but I do think it definitely needs a ground...

Any advice out there?

Thanks!

[eagle_andy]

There is a device called a grounding block that goes in line with your cables. Should be able to locate at a local retailer.

[scooper]

Or Radio Shack, Home depot, Lowes, etc...

Just take your SW21's out, and replace with the grounding blocks.

[mrmoose2003]

OK, good idea. I already have a grounding block in the line (up in the attic, but the tech who put in the dish 500 adding the outside ground, too.

[AntAltMike]

You are required to ground the mast and to ground the coax downleads as near as possible to the point at which they enter the building. The lug on a SW-21 does not ordinarily satisfy the mast grounding requirement, though if the SW-21 case was securely attached to the mast mounting bracket with sheet metal screws, then it might meet that requirement.

As a general rule, a SW-21 is not located at a point as near as possible to the point at which the coax enters the building. One exception is when the wires from the dish go almost immediately into the attic. This point can actually be inside or outside the building, and the ground connection point can be inside or outside, but common sense tells us that it is better to have both connection points outside.

You need to run 10 gauge copper or 8 gauge aluminum solid or stranded, or a 17 gauge copper plated steel wire from the mast to the building ground electrode, which is the building's ground rod or ring, the cold water pipes (including the external water faucet) and the electrical meter box. You cannot connect it to a separate ground rod unless that rod is also connected by 6 gauge wire to the ground electrode.

You also must ground the coax outer conductor with a groundwire that is approximately equal in current carrying capability to the outer conductor (shield). 10 gauge copper will do, and cable companies often use 12 gauge for this ground. It must be solid wire and insulated.

[Paralyn]

My antenna is on a pole, sunk into the ground with QuickCrete around it. I have to assume that that grounds the antenna. Then each of the two SW-21's have a aluminum ground wire going to a Radio Shack copper ground rod (about 6 feet long) which is pounded into the ground about 2 feet away from the mast/pole. Does that meet specs?

I try to stay away from grounding to cold water pipes. In our neighborhood a lot of homes have had to re-plum their pipes due to pinhole leaks cause electronic related corrosion.

[AntAltMike]

Not even close. I have read that under some circumstances, a mast that is sunk 4 feet into the ground and made of certain composition can satisfy the mast grounding requirement. On the other hand, the last time I actually read the model code (1990 edition) it was not clear that a mast in a yard had to be grounded. I believe section 810 refers to grounding masts on buildings.

A separate ground rod does not satisfy the code requirement unless it is at least eight feet long and bonded to the building's ground electrode with 6 gauge or larger wire, so if you are going to bond the ground rod, you might as well run the ground connection directly to the ground electrode and leave out the rod.

I am not familiar with any "electronic related" corrosion. Mast and coax grounds do not ordinarily carry any current. It is more likely that if someone clamped dissimilar metals together (copper and aluminum), there would a corrosion reaction at that junction. I never use the aluminum ground wire for that reason. The industry standard 3/4" water pipe clamps, which I think are zinc plated, can take an aluminum ground wire and clamp it reliably to a copper cold water pipe.