Routing Options GEC for roof mounted Antenna Bonding Interconnection across Driveway

[ryanman0]

Greetings,

A rooftop antenna is grounded via 6AWG solid copper GEC (in Schedule 40 PVC) running down the roof and exterior of the one story home to a 10' rod. This is not presently connected to the intersystem bonding termination bridge. We are about to perform a Main Panel replacement and need to interconnect this per 2008 NEC 250.94. The challenge is that almost half of the home is surrounded by concrete. After a couple of failed attempts at boring a pvc run under a 30 foot driveway through extremely dense clay, we are considering other options for the bonding inter?connection.

Can we simply Run 4AWG solid copper in schedule 80 PVC up and then horizontally against the side of the brick building. There is a garage door that we would have to go on top of to do this. The distance of such a run would be almost 50 feet with 30 of these feet being horizontal runs just under the eves and around the corner towards the bonding termination bridge. 4AWG was being considered to reduce voltage drop on the long run. If not, should we just cut the long run into the concrete of the driveway and around the corner, lay down pvc, concrete over it. Any other options?

Also, the RG6 coax cable entering the building from this antenna down towards the television has a separate ground wire attached to it. This wire is also connected to the mast. However, the wire is presently not connected to anything on the other end inside the home.

Thank you,
Ryan

 

[Smart $]

Welcome to the forum... :thumbsup:

What is the purpose of the antenna?

Assuming it's a radio and/or television receive-only antenna, please read and comprehend as best possible 800.21 in its entirety... then come back and post any additional or repeat questions you have...

 

[ryanman0]

Thank you for the reply and pointing me to the relevant section. Its a television receive-only antenna. After reviewing 800.21, Everything seems fine regarding A,B, C, D, H, I, K (Copper, insulation not required, supports, Mechanical Protection, Size, single grounding conductor, Electrode Connection). However, I'm still confused regarding Section E, F, G, and J as follows:




E: "shall be run in as straight a line as practicable"
Well, in its current state, the grounding conductor runs directly from the mast down and down the wall to a 10' grounding rod. So that run meets this requirement. However, does this section E: also apply to the "bonding jumper" mentioned in section J (between the television equipment grounding electrode and the power grounding electrode)? If it does apply to the bonding jumper, would a run that travelled back up the wall about 7 feet to get over the garage (as described in the previous post) likely be considered "as straight a line as practicable" even though crossing the driveway might be an option.

F1-F3: ( depends on if the building has Intersystem bonding termination).
Well, it does have an Intersystem bonding termination near the meter. So, does this mean we need to discard the connection to the antenna's dedicated 10' grounding electrode and instead run the GEC directly across the roof towards the side of the house where the intersystem bonding termination is located? I do not see anything forbidding having both connections. Should we leave the current connection in place and also run a new wire from the mast to the Intersystem bonding termination. If we did this would this meet the requirement for section J (bonding jumper) and also serve as the bonding connection?

G: (allows grounding conductor to be run either inside or outside the building). Does this apply to the bonding jumper connection also in section J. I do not see any requirement listed stating that the bonding jumper be buried.


J: bonding jumper... between ... television equipment grounding electrode and the power grounding electrode ... where separate electrodes are used.

 

[Smart $]

... However, I'm still confused regarding Section E, F, G, and J as follows:

...

First, I'm glad to see you made the connection to 810.21 when I cited 800.21 in error... :ashamed1:

Yes, E applies to J.

No it does not mean the "dedicated" electrode must be abandoned. It's optional... but to abandon it, you would have to remove it (technically ). Article 250 requires all electrodes present to be connected into the grounding electrode system... and that includes this "communications electrode". The Intersystem Bonding Termination (IBT) is really intended for grounding communications systems, but not additional electrodes. Technically, there is no such thing as an communications equipment electrode where a power grounding electrode system exists on premises.

As it stands, by the requirement of F1, the connection must be to the IBT. There have been reports, though, that community communications systems installers, especially "Cable", do not use the IBT, using the methods of F2 instead. I personally don't see using F2 methods as non-compliant when an IBT exists, especially when an F2 method is more convenient (HINT)... but Code is what it is.

G is a carryover from E. Simply put, the bonding jumper must be run in the shortest, straightest, practicable path... but practical enters the picture in that it is undesirable for the bonding jumper to be installed in mid air and unprotected from physical damage... so also along structural members (which includes earth or any pertinence affixed thereto).

Another tip which I don't recall as written in Code, is to not make sharp bends in your bonding jumper for an antenna mast. While fault current is predominant on the paths with least resistance, lightning current has high voltage stress which causes the current to sometimes track straight rather than following a bend in the conductor. This is mostly important where the conductor is run on or near combustible objects.