Grounding the automated station

[user220]

Howdy folks,

First off, I apologize if this has been discussed before – didn’t see it on the website(s), at least…

I did see in the automated receiver station parts list (from website) that a grounding rod and copper wire are needed for the tower installs, but are folks using this for the mast/tripod, the boom arms, the antennas, and/or the coaxials?

Thus far, I’ve only attached antennas to existing towers (Rohn type) or an existing antenna bank; and I have not added any grounding to those – neither the booms or the coaxials. I had assumed that the grounding of the tower would translate to the grounding of the antennas and booms due to metal on metal contact. Is that a safe assumption?

Either way, I’ve now learned that coaxials need grounding which means they must run through a grounding block; this adds another connector (= some signal loss potential?) – one block per coaxial (or a multi-block). Fortunately, they are very inexpensive, but it means cutting and adding plugs to existing coaxials (or buying more jumpers).

I have been given the opportunity to utilize a tower that is used for public safety and was told “no problem, just make sure that it’s well grounded.” I will ensure that what I do is acceptable on their end (Dept. of Public Safety), but tentatively, have any of you used existing towers and what all did you ground? Have any of you grounded the coaxials?

Thanks! Sorry for all the novice questions!

Respectfully,

Michael Seymour

mseymour@wlf.la.gov

Michael Seymour

Ornithologist & Scientific Collecting Permits Coordinator

Louisiana Dept. of Wildlife & Fisheries

Louisiana Natural Heritage Program

2000 Quail Drive, Room 229

P.O. Box 98000

Baton Rouge, LA 70898-9000

Office: 225-763-3554

Fax: 225-765-2818

mseymour@wlf.la.gov

DWH Attorney Work Product/Attorney-Client Communication

DWH SettlEment Confidential

[SAMIAM]

Dear Michael,

Thanks for your great questions. Please take the advice of professionals or well-seasoned amateurs in the field, or the references cited here. I welcome being corrected by those that may know better than I. There is a great summary here - http://www.solacity.com/lightning-protection/, but note that it’s probably a little too comprehensive for most of our needs.

As far as I know we have not had any lightning strikes across the array, but with more stations coming online in sub-tropic and tropical climes, it’s inevitable. Depending on the setup, I generally feel that if the majority of our stations were to be hit by lightning, there will be a lot of problems to rectify regardless of grounding. However, that does not mean we shouldn’t prepare. Aside from the pop-up towers, almost every setup is going to be different so there isn’t a one size fits all solution.

For the pop-up towers, I’m not aware of anyone grounding them specifically as the mast, tripod and guy wires all serve as a ground of some sort. However, others suggest grounding each guy cable - see links below.

For antenna fixed on other types of towers, there will often be other grounding wires that can be tied into, or the tower will already be grounded. When this is not the case, copper wire (moderate gauge) is typically attached to each foot of the tower if possible and run to one or many deep metal rod/rebar in the ground. I’ve read/been told that there is little point grounding something near the top of the tower due to the to the sheer volume of steel you’re trying to compete with.

Grounding is most common on building/tower fixtures where there is not a natural ground or other electronics are at potentially greater risk. In these scenarios you’ll want to setup a ground to intercepting the current before it has a chance to go into the building.

As for your ‘safety tower’, it depends if it’s already grounded, steel, wood, etc? Happy to discuss offline if necessary.

You’re the first person that I’ve heard of grounding individual coax cables - there is lots of information here - http://www.arrl.org/files/file/Technology/tis/info/pdf/0207048.pdf? This could be problematic for the amateur because of signal loss, but also cables connections can be finicky, especially if new breaks or adapters are installed.

The best source for information on a lot of what we do can be found in the amateur/ham radio world - see http://www.arrl.org/lightning-protection and http://www.solacity.com/docs/Polyphaser/An%20overview%20of%20lightning%20protection%20for%20ham%20radio%20stations.pdf.

Cheers,

Stu

[user126]

There is a bit of info and experience among those doing passive bat acoustics on this topic (similar set up with tall metal pole connected to electricity and quite capable of conducting/attracting electricity), and some of the more experienced may be a good source of info as well. I would start with the companies directly. But, if having problems and no results, I could provide some personal consultant contact info for a few well experienced folks that may provide some useful tips willingly. That would be on private basis of course unless they consented to group email exchange.

Greg Turner

Endangered and Non-Game Mammal Section Supervisor

Bureau of Wildlife Management

PA Game Commission

2001 Elmerton Avenue

Harrisburg, PA 17110

cell: 814-599-7883

email: grturner@pa.gov

Join the Pennsylvania Mammal Atlas today!

www.pamammals.org

[user220]

Stu (all),

Thanks for the quick and helpful replies; I’m perusing the links now. I’ve corresponded with another colleague with N Gulf of Mexico towers, and he grounds the towers (not the coaxials) with copper wire and a grounding rod.

I will have to give some serious thought to the added expense (but also added height!!!) that utilizing a 250’ tower entails… Until yesterday, I was only planning on grounding the pop-up stations (NOT the coaxials); but now… well, I guess I’m still really only planning on grounding the pop-up stations (NOT the coaxials) – unless I’m tying in to someone else’s tower! : )

Repasting one of your links (a “,” made it into your hyperlink) http://www.solacity.com/lightning-protection/

Thanks again!

Respectfully,