Grounding a Diamond D130J?

[GeneseeCoMI]

The issue of site grounding and bonding, while not all that complicated, can be a bit complex to understand at first. If you really want to understand the issue there are several documents to study and understand.

NFPA 80 - National Electrical Code

Motorola Standards & Grounding for Communications Sites http://www.repeater-builder.com/antenna/site-stuff/are-fifty-six-man-2005.pdf

Harris Site Grounding & Lightning Protection http://www.repeater-builder.com/ge/lbi-library/t4618r3a.pdf

BICSI Standard for Telecommunications Bonding and Grounding Planning and Installation Methods for Commercial Buildings https://www.bicsi.org/book_details.aspx?Book=BICSI-607-CM-2011-v5

Good info. I think the electrician will be able to figure it out.

 

[DisasterGuy]

Good luck. Most electricians get lost on anything beyond AC grounding.

 

[GeneseeCoMI]

Well they came over today and I gave them some documents and they went out and bought the supplies but they said they'd have to call the power company tomorrow to find out where it's safe to install the rod. They also said they might not be able to keep the cable in a straight line and they'd run it along the roof and walls of the building instead. Is that safe to do? I was wondering if it was a fire hazard or not, or if it will affect my reception or cause interference.

 

[mmckenna]

Checking with the utilities probably means they are going to do an "underground service alert" call to have the utilities identify anything that's underground in that area. Always a good idea, and I think in some cases mandated. If a contractor fails to get the USA done and ends up hitting a utility, then they are liable for any damage.

 

[GeneseeCoMI]

Checking with the utilities probably means they are going to do an "underground service alert" call to have the utilities identify anything that's underground in that area. Always a good idea, and I think in some cases mandated. If a contractor fails to get the USA done and ends up hitting a utility, then they are liable for any damage.

Yeah I understand that. I see those "Miss Dig" signs and ads all the time. What about them running the wire along the building? That's what I was wondering about more so.

 

[mmckenna]

What about them running the wire along the building? That's what I was wondering about more so.

Not sure why they'd need to check with the utility. I'm not in a lightning prone area, so I'm not sure if they do things differently than here.
Are these guys electricians, professional installers, or someone else?

 

[GeneseeCoMI]

Not sure why they'd need to check with the utility. I'm not in a lightning prone area, so I'm not sure if they do things differently than here.
Are these guys electricians, professional installers, or someone else?

I wasn't talking about checking with the utility about the cable. They're doing for burying the rod. I understand that part.

What I really want to know is does the cable need to be in a straight line to avoid being a fire hazard and/or an RF interference magnet, or will it be okay if they run it along the roof and wall of the building?

One guy is an electrician and the the other is a general contractor.

 

[mmckenna]

My understanding and from what I've seen at numerous tower sites is that in an ideal world you really want the cable in a straight line. You want to provide the shortest path to ground for any lightning strikes.
Any bends need to be gradual. Any sharp bends or points can be a problem.

If you look at lightning protection systems for buildings, you will often see that the grounds are run along the edges of the rooftops coming down from the peak to the edge and continuing down to the ground.

^^^^^That's for a lightning ground.

For an RF/static ground, you just want a low impedance path to ground. That's usually a heavy gauge cable taking a short path to ground. I usually ground our gear with #6 or larger and as short a run as possible.


I think for an RF/static ground, you'll be fine if it runs along the edge of the roof to your ground rod.

 

[mmckenna]

What I really want to know is does the cable need to be in a straight line to avoid being a fire hazard and/or an RF interference magnet, or will it be okay if they run it along the roof and wall of the building?

I'd add that any lightning strike directly to your antenna is going to be a fire hazard, ground or not. You'd be looking at several million volts and a whole lot of amps all trying to find a way between ground and cloud. A thin layer of insulation, paint, electrical tape, shiny new scanner, etc. is not going to stop it. That much juice trying to get where it's going is going to heat things up very fast. Fire is going to be a real risk in a residential environment.
What you are ideally trying to do is to give as clean a path as possible between your antenna/mast and the ground. Some of it will find other paths.

I was on a ship once that got hit by lightning. Lots of antennas, radar, etc up on the mast. No damage at all to any of that equipment. What got knocked out was an engine management computer down in the engine room. Lightning doesn't necessarily want to follow our rules, although we can do our best to get out of it's way. That's really the best you can do.

It sounds like you are doing the right things, and I understand your concerns about wanting to make sure it's done right. NEC requires what you are doing, many scanner/SWL/Amateur radio operators ignore it. You are likely way ahead of the pack. It'll be interesting to see if this has any effect on your noise issues. All I can really say is that none of this should hurt things.

 

[GeneseeCoMI]

My understanding and from what I've seen at numerous tower sites is that in an ideal world you really want the cable in a straight line. You want to provide the shortest path to ground for any lightning strikes.
Any bends need to be gradual. Any sharp bends or points can be a problem.

If you look at lightning protection systems for buildings, you will often see that the grounds are run along the edges of the rooftops coming down from the peak to the edge and continuing down to the ground.

^^^^^That's for a lightning ground.

For an RF/static ground, you just want a low impedance path to ground. That's usually a heavy gauge cable taking a short path to ground. I usually ground our gear with #6 or larger and as short a run as possible.


I think for an RF/static ground, you'll be fine if it runs along the edge of the roof to your ground rod.

Thanks for the info. I guess I'm worrying for nothing.