Do you need to GROUND an attic antenna?

[squale]

Lets say I got a Scantenna or a Diamond Discone antenna and put it in my attic (I have a standard Bi-Level with plywood roofing and regular fiberglass shingles or whatever they are made out of. If I just stuck the antenna in the attic and ran the Coax about 20 feet to the scanner, would I need to GROUND the antenna? or no, because there is no way lighting could strike it being in the attic? the antenna would in the attic next to the right side of my house so I don't know if lighting could somehow still find it's way in to hit the antenna...?

I have read in another thread that putting the antenna in the attic would be the same reception quality as putting the antenna outside at the same height.. is this true?

 

[N_Jay]

Putting an antenna in the attic is NOT as good as putting it outside.

The difference will depend on the roofing and the band (and what you want to listen to).

There is a MISCONCEPTION that antennas attract lightening. AN antenna is no more or less likely to be struck that any other conductive object.

The antenna in your attic is just as likely to be struck as the wiring in your attic.

 

[squale]

okay so you DON'T have to ground the anteanna in the attic as you would have to do if it were outside?

my roof is made out of 1/2" plywood with fiberglass shingles. I am interested mainly in getting Airband (108-137mhz)

 

[jhooten]

Consult your local building code and National Electrical Code. The short answer is yes a safety ground is required.

"NEC 810.15 Grounding. Mast and metal structures supporting antennas shall be grounded in accordance with 810.21"

 

[N_Jay]

Consult your local building code and National Electrical Code. The short answer is yes a safety ground is required.

"NEC 810.15 Grounding. Mast and metal structures supporting antennas shall be grounded in accordance with 810.21"

Hmmm, wonder if that applies if inside.

My guess is the NEC people never considered an inside antenna.

Also, NEC is not required everywhere.

That said, it never hurts to ground an antenna.

 

[squale]

yeah that was the question whether you need to ground it INSIDE the attic or not.. I would think NOT

 

[N_Jay]

yeah that was the question whether you need to ground it INSIDE the attic or not.. I would think NOT

Well, don't think too hard when it comes to the NEC.

A lot of the rules do not have simple logical reasons.

 

[Thayne]

I bet if you asked 10 Electrical Inspectors you would get at least 5 different answers. :roll:

Like NJay said, it's no more likely to be struck than anything else in your attic

 

[bsavery]

It also depends on what year NEC code is in effect in your city.

As N_Jay says... not every city has building codes. Many small cities leave it up to the county. Most counties that don't specificly address building codes, defer to the state. And that I know of, no state has not adopted the full NFPA code set (of which the NEC is a part). That's why the codes always state to check with the Authority Having Jurisdiction.

I can tell you that as of the 2004 NEC and NFPA 101 (which covers Life Safety) codes, there is no requirement to ground a receive only, internal antenna system. Transmission antennas and cables I'd have to pull the code books and check, but I'm fairly certain they do not require grounding as well.

What I do know though is if you accidently short the shield to building steel some ways down the line, you get nothing but noise out of the cable!

Bob

 

[wwhitby]

About 10 years ago I rented a house and had to put my antennas in the attic. I was pleasantly surprised by the results, so I’ve kept doing it.

None of the antennas in my indoor farm are grounded. The way I look at it is that they are all below (under) the roof line, plus since they aren't attached to anything metal, they should be insulated.

On Memorial Day, 1999, my house took a lightning strike. Lightning struck the vacant field next to my house and entered through the cable, telephone, and electrical grounds. It blew vinyl siding off the house, blackened electrical outlets and destroyed every TV, VCR, telephone, and every modem in the computers. I also got a nasty shock, since the electricity came through my computer keyboard and zapped me. My radio equipment, which was protected by a heavy duty surge protector, as well as being off, was fine. I've always thought that if I would have had some of it plugged directly into the wall outlets, might have suffered the same fate as the other electronics. The point I’m making is that lightning didn't come in through the antennas, but the normal household electrical grounds.

Warren

 

[N_Jay]

The way I look at it is that they are all below (under) the roof line, plus since they aren't attached to anything metal, they should be insulated.

Except that it is grounded through the coax since your radio is grounded at the power plug.

 

[jhooten]

The section I quoted is from article 810 "Radio and Television Equipment" Section II "Recieving Equipment--Antenna Systems" in the 2002 book (the newest one in the library).

Safety grounds are not just about Lightning. Should your antenna come in contact with a live conductor while you are working on it you may become the path to ground for the current in that conductorand we all know what that can cause.

 

[wwhitby]

The way I look at it is that they are all below (under) the roof line, plus since they aren't attached to anything metal, they should be insulated.

Except that it is grounded through the coax since your radio is grounded at the power plug.

Correct. What I should have said was that the antennas are insulated from being the primary point where lightning would enter your home.