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Old 25-Aug-2014, 7:57 PM   #1
ralfagus
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Need help/opinions on my install

I installed a winegard HD7698P on a 1 1/4" EMT pipe 10' tall on the roof.
I drilled a hole through 2nd story roof overhang and used U brackets to hold mast against 2x4 rafter under roof overhang. The bottom of the pipe rests on a 2' section of 2x4 that sits on the roof of my 1st floor roof. There is about 3' between 2nd story roof overhang and fist story roof.
Grounded coax with grounding block and mast using #10 insulated stranded copper wire to service grounding rod. Grounding block and mast have their own ground wire. Used screw side of existing grounding clamp to press wires against rod since there wasnt enough space for new clamp. Ground rod was under service panel between exterior and interior garage wall so I had to drill hole in exterrior stucco wall to get to rod.

Questions are:
Is it ok to run mast through the roof overhang like I did?
Is it ok to use same grounding clamp as service ground wire?
Is it ok to run the grounding wires through exterior wall to get to grounding rod within the wall?
Can one attach grounding wires to electrical service panel instead?

I just want to make sure im not doing something wrong as this is my first time mounting an antenna.
Below is a picture of the grounding clamp and can provide more pictures of the install when I get home if it helps.


Last edited by ralfagus; 25-Aug-2014 at 8:00 PM.
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Old 25-Aug-2014, 10:04 PM   #2
GroundUrMast
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If the mast passes through the roofing material and underlying sheeting, you'll certainly want to have an appropriately sized flashing / boot to stop rain water from damaging the structure under the roofing material.

Quote:
Is it ok to use same grounding clamp as service ground wire?
I'm sure the NEC would require the connector to be approved for terminating two wires. However, if the connection is electrically sound and mechanically secure, it will no doubt function.

Quote:
Is it ok to run the grounding wires through exterior wall to get to grounding rod within the wall?
The NEC says you can run grounding conductors into and through the structure. When grounding an antenna system, I avoid this if possible. I would prefer to keep fault current out of my house to the degree I'm able.
Quote:
Can one attach grounding wires to electrical service panel instead?
Yes, but be sure to understand the hazards involved when working around energized equipment. It is no doubt much safer to place an appropriate clamp on the exterior conduit that attaches to the meter base (presuming it's accessible).
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If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)

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Old 26-Aug-2014, 2:56 PM   #3
ralfagus
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Thank you for the info. I noticed the rod I attached the ground to is rebar.
Is that normal. I see what looks to be a thicker copper cable atraches to it which I think is one of the service box ground wires.
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Old 27-Aug-2014, 3:44 AM   #4
GroundUrMast
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Quote:
I noticed the rod I attached the ground to is rebar.
Is that normal.
It sounds like you have a "UFER" ground system. It's becoming more common to see the foundation steel used as the primary grounding electrode. Codes recognize this as an acceptable grounding electrode that is generally superior to one or more driven rods. (Often, the impedance of driven rods will be several orders of magnitude greater than that of the "UFER" system. The ideal is a very low impedance.)
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Old 27-Aug-2014, 7:05 AM   #5
ralfagus
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Thanks again! I just wish there was enough space for another clamp. It only sticks up from the concrete far enoughto to allow one clamp.
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Old 27-Aug-2014, 10:32 AM   #6
Stereocraig
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So, would a 25G tower in 2160# of concrete provide an acceptable ground?
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Old 27-Aug-2014, 5:44 PM   #7
GroundUrMast
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My understanding of the generic NEC requirements for this type of grounding conductor is that at least 20 feet of steel needs to be encased in at least 2 inches of concrete, close to the area where the concrete and soil meet. The bonding conductor between the electrical service and UFER ground is supposed to be #4 AWG. Also, the code requires that all other grounding rods, buried pipe, etc. must be bonded together, to form a single contiguous system. These bonding conductors are generally required to be #6 AWG.

So, Im uncertain if there is enough steel in your tower foundation to qualify it as a UFER ground capable of serving as your sole electrical service ground. I'm inclined to think that if bonded to your electrical service, it would very likely provide a superior connection to earth as compared to a a typical driven rod.

As always, a connection to earth is only one element in the grounding / bonding system. Solid, reliable bonds and grounding conductors that are capable of handling fault current loads are vital to preventing dangerous voltage differences between grounded objects.
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If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)

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Old 30-Aug-2014, 9:48 AM   #8
Stereocraig
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It's only about 15' from my service entrance and I have plenty of solid #6.
Cheap insurance, for sure.

On a side note, we had some really close strikes yesterday AM and we lost our router.
Nothing else was affected, so maybe it was just coincidence.
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Old 17-Sep-2014, 6:53 AM   #9
ralfagus
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I wanted to ask if its ok to ground your mast and rg6 to the exterior of the electic utility box instead of using the same grounding rod & clamp as the electrical panels ground wire? Im planning to use 2 clamps like the one below to the exterior of my meter box. I see cable and satellite companies use this grounding method. Would this put me in compliance with NEC code?

Also, I know solid core #10 is better than stranded but home depot here only has stranded and had to use that. Is stranded adequate?

Im using a grounding clamp (similar to the one by groundurmast's name) attached to the mast above where the EMT conduit (mast) comes out above the roof instead of at the bottom (below roof). Is that ok or is there reason it has to be at the bottom? I am asuming any energy captured would be best to be kept from going through the roof material.



Heres a pic of my setup in case it aids answering any of the questions.

Last edited by ralfagus; 17-Sep-2014 at 7:15 AM.
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