Antenna grounding

[bizkymo]

Hello. I grounded my antenna recently and I'm not sure if I did it correctly. Maybe one of you guys can help me out. Is it okay to attach a ground wire to the antenna mount and not the mast? I assume this is okay since the mast is connected to the mount.

Is it okay to attach the ground wire running from the mount to the ground wire connected to the cable ground block? Or should I have used two ground wires, one from the mast, one from the cable and connect them both separately to the cold water pipe?

Finally, is it safe to have cables lying on the roof top? Would snow, rain, and win cause them to deteriorate rapidly?

[LeeS]

bizkymo,

Welcome to HDTVoice!

Is it okay to attach the ground wire running from the mount to the ground wire connected to the cable ground block? Or should I have used two ground wires, one from the mast, one from the cable and connect them both separately to the cold water pipe?

Who picked the cold water pipe for the ground? I'd use a grounding rod driven into the ground. See the RadioShack supplies. Personally I'd run two grounds to the rod. One from the coax grounding block and one from the mast. See the paragraph below, the last sentence is the one to read for sure.

Antenna grounding supplies at RadioShack: http://www.radioshack.com/category.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F003%5F001%5F003%5F003&Page=1

Article on antenna grounding from Keohi HDTV: http://www.keohi.com/keohihdtv/hdreception/antenna_grounding.html

Here is one paragrah, the last sentence says it all:


In an antenna you can ground the mast, the boom, the dish, the director and reflectors of the antenna by contact metal bonding to a ground wire run directly into the earth via a deep ground rod, but you cannot directly ground the driven element or active element of the antenna. All you can do is make a reasonable attempt at grounding it via a special coax grounding block to reduce static charge buildup and reduce probability of a hit. In a Log Periodic yagi most of the elements are driven so that most of the antenna structure can not be grounded directly. In this case it is wise to use a coax grounding block. This block is a device designed to bleed off high voltage spikes that reach dangerous levels that would damage your receiving equipment. They don't directly short out the center conductor to the ground because this would kill the signal but rather allow a small gap that will on a continuous basis bleed off the building static charge before it reaches dangerous damaging levels to your equipment. Using one of these grounding blocks located just before the coax feed wire enters your building is what is recommended to effectively reduce the probability of small static electricity damage to your receiver. It will NOT protect against a direct lightning hit. Both the grounding block on the coax and a direct ground wire to the mast of the antenna should be used.

If I had to run wires across a roof (which I would try to avoid) I would try to keep the wires from moving around, you could damage the wires and/or the roof. I'd really try to find a mounting position that didn't require stringing wires across the roof.

There are lots of good FAQs to read, but checkout the ones on OTA and Antennas at least.

Good Luck,
Lee

[Architectural_Drafter]

Hi there!

(Sorry if I start rambling... I should have been asleep about an hour ago...) :drool2:

I agree with LeeS, but in all of the posts about grounding, the one thing I notice is that no one recommends disconnecting the equipment when storms might be around. I personally don't believe that any ground system would protect electronics from a direct hit. (Yes, I'm paranoid.) I'd like to be wrong about that. And separate ground lines seem to be a good idea (even though mine isn't set up that way).

I'd be interested in knowing what others here do when storms abound.

If you must run wires on a roof, either elevate them or at least run them straight down-slope. Deteriorating cables aren't really the issue. That expensive roof surface keeping the water from damaging the expensive interior of the residence is.

Oh, and check to make sure there aren't any utility lines/pipes where you place that ground rod.

If in doubt, call a professional. It's hard for a do-it-yourselfer to defer to someone else like that, (I know....) but the piece of mind is well worth it.

And as everyone here will tell you, don't forget the drip loops! :)

[LeeS]

I'd be interested in knowing what others here do when storms abound.
We don't get that many lightning storms but we disconnect equipment too.

In 1994 we were struck, had the power disconnected but didn't disconnect the cable to the TVs. The power company's theory was that it was a ground to sky burst. The energy went through all the grounds including the cable ground, took out all the phones, modems that were hooked to the phone lines and the computers the modems were in. Destroyed the tuners in the TVs and A/V receiver (from the cable ground), the tuner in the VCR.

We are between two mountains (hills) and by no means the highest point around. Just our time I guess.

Unhook everything and be safe.

Lee

Forgot to mention, all our cables are underground, electrical, phone, cable etc.

[Architectural_Drafter]

Ouch. Ouch ouch ouch...
We had a close strike once. Actually hit the neighbor's house. Lightly zapped my wife (she was on the phone) and destroyed a light switch. The neighbor lost every thing even slightly electronic in his house, except his computer. It was surge protected, but the modem wasn't. Still, it survived.

We're in Iowa, so we have weeks where it seems there's a storm every day. Even a hint of thunder has me running through the house yanking cords and cables.

I remember a hit on our house when I was young, back in the '70's. Fried an outlet. We had sparks showering out across the kitchen. Wouldn't blow the fuse, though. Weird...

[twonami]

I made my own ground rod by getting some 1" copper pipe, sweating a cap on it and driving that puppy into the soil. I only did it cause nobody in my area had any in stock. My ground wires are soldered to the pipe too.

[Ratman]

I made my own ground rod by getting some 1" copper pipe, sweating a cap on it and driving that puppy into the soil. I only did it cause nobody in my area had any in stock. My ground wires are soldered to the pipe too.

You know that the recommend depth for a ground rod is ~6' and solid?
Also... do you think that lightning won't melt solder? ;)
At least use clamps!

[twonami]

it is 6ft in and has holes drilled into it and soldered with a propane torch so I think it's pretty secure, I wet the heck out of the soil and it pounded in real easy. HomeDepot special :)

[Ratman]

Just to point out....

On average, solder is liquid at ~450 degrees F.
On average, a bolt of lightning's temperature is ~30,000 degrees F.

Of course, that is not the temperature that will get to the solder joint, but there will be heat. Not hot enough to turn copper to liquid, but definitely to turn solder to liquid.

I really believe that you should seriously consider using a $1.00 ground clamp.

[twonami]

a $1.00 clamp, thats outrageous!!! :wow: OK, I got some in my tool box. :rockon:

[Ratman]

LOL...
I'm glad I "sparked" your interest.
P.S... No "charge" for the advice!
;)