dslreports logo
 
    All Forums Hot Topics Gallery
spc
uniqs
50

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

1 recommendation

Jack_in_VA to cowboyro

Premium Member

to cowboyro

Re: [Roofing] My weekend project - OTA Antenna

A direct lightning strike will turn most anything to vapors. There is NO PROTECTION that's cost effective or will offer protection to a residential dwelling. All the Blacks around here have Lightning rods and ground wires running everywhere connecting them.

I have the same antenna and while lightning has made toast of my Directv dish several times the antenna is ok.
iknow_t
join:2012-05-03

iknow_t

Member

said by Jack_in_VA:

A direct lightning strike will turn most anything to vapors. There is NO PROTECTION that's cost effective or will offer protection to a residential dwelling. All the Blacks around here have Lightning rods and ground wires running everywhere connecting them.

I have the same antenna and while lightning has made toast of my Directv dish several times the antenna is ok.

what are the Whites doing to protect theirs?? surely, a proper Lightning rod system will attract the Lightning and send it safely to ground.

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

1 edit

Jack_in_VA

Premium Member

said by iknow_t:

said by Jack_in_VA:

A direct lightning strike will turn most anything to vapors. There is NO PROTECTION that's cost effective or will offer protection to a residential dwelling. All the Blacks around here have Lightning rods and ground wires running everywhere connecting them.

I have the same antenna and while lightning has made toast of my Directv dish several times the antenna is ok.

what are the Whites doing to protect theirs?? surely, a proper Lightning rod system will attract the Lightning and send it safely to ground.

Nothing. I've never seen a lightning protection system on any houses in this area other than the older Blacks.

cowboyro
Premium Member
join:2000-10-11
CT

cowboyro to Jack_in_VA

Premium Member

to Jack_in_VA
said by Jack_in_VA:

A direct lightning strike will turn most anything to vapors. There is NO PROTECTION that's cost effective or will offer protection to a residential dwelling.

You couldn't be further away from truth.
Virtually all houses in Europe have lightning rods, and they work. Of course the grounding "wire" isn't a wire, it's more of a thick steel band.
The current of a strike is typically in the 10,000A range and extremely rarely exceeds 100,000A. The strike lasts no more than 200ms. It is fairly simple to calculate the minimum thickness of a wire that will dissipate lower heat than what it takes for it to overheat.

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA

Premium Member

Big difference we're not in Europe. No need to cite anything there.

I am familiar with lightning protection designed by companies with engineers with the expertise. Buildings with different height air terminals and yes they are connected with "round" bare aluminum cable tied to the building grounding system.

cowboyro
Premium Member
join:2000-10-11
CT

cowboyro

Premium Member

said by Jack_in_VA:

Big difference we're not in Europe. No need to cite anything there.

The laws of physics are the same. The thicker the cable the lower the heat dissipation and the higher the thermal mass the lower the temperature gain.

alkizmo
join:2007-06-25
Pierrefonds, QC

alkizmo

Member

said by cowboyro:

The laws of physics are the same. The thicker the cable the lower the heat dissipation and the higher the thermal mass the lower the temperature gain.

I think he was debating on whether the grounding wire has to be hooked up to rods or just the building grounding system.

In my case, it is hooked up to the house's grounding system, which is the cold water copper pipe.

The OLD antenna has a bare round/solid aluminum cable that only went to a grounding rod. That cable was unflexible, thus uglily protruding from the cable path. I replaced it with braided 10AWG copper that clamps THROUGH the original ground rod and continues inside the house to the copper pipe

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA to cowboyro

Premium Member

to cowboyro
said by cowboyro:

said by Jack_in_VA:

Big difference we're not in Europe. No need to cite anything there.

The laws of physics are the same. The thicker the cable the lower the heat dissipation and the higher the thermal mass the lower the temperature gain.

Do you have a lightning protection system on your home?
iknow_t
join:2012-05-03

iknow_t to alkizmo

Member

to alkizmo
said by alkizmo:

said by cowboyro:

The laws of physics are the same. The thicker the cable the lower the heat dissipation and the higher the thermal mass the lower the temperature gain.

I think he was debating on whether the grounding wire has to be hooked up to rods or just the building grounding system.

In my case, it is hooked up to the house's grounding system, which is the cold water copper pipe.

The OLD antenna has a bare round/solid aluminum cable that only went to a grounding rod. That cable was unflexible, thus uglily protruding from the cable path. I replaced it with braided 10AWG copper that clamps THROUGH the original ground rod and continues inside the house to the copper pipe

that's going to look like an open circuit to the 1 GHZ frequency of a lightning strike though..

alkizmo
join:2007-06-25
Pierrefonds, QC

alkizmo

Member

said by iknow_t:

that's going to look like an open circuit to the 1 GHZ frequency of a lightning strike though..

What am I supposed to do? A ground rod perimeter surrounding my house all bonded with 6AWG?

tschmidt
MVM
join:2000-11-12
Milford, NH
·Consolidated Com..
·Republic Wireless
·Hollis Hosting

1 edit

tschmidt

MVM

Welcome to the ranks of OTA TV viewing. I'd much rather spend a few hundred dollars every few decades than $100 a month for the privilege of watching commercials.
said by alkizmo:

What am I supposed to do? A ground rod perimeter surrounding my house all bonded with 6AWG?

Agree with iknow_t See Profile the lower the impedance the better. The goal is to minimize voltage differences between metallic objects in the building.

Assuming the antenna is some distance away from building ground then a driven ground rod at the antenna with antenna, ground electrode and building ground bonded with 6AWG. The coax should pass through a grounding block where is enters the building and a gas tube coaxial surge suppressor at the ground block can't hurt.

/tom

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA to alkizmo

Premium Member

to alkizmo
said by alkizmo:

In my case, it is hooked up to the house's grounding system, which is the cold water copper pipe.

The OLD antenna has a bare round/solid aluminum cable that only went to a grounding rod. That cable was unflexible, thus uglily protruding from the cable path. I replaced it with braided 10AWG copper that clamps THROUGH the original ground rod and continues inside the house to the copper pipe

(1)Hooking it to the cold water pipe is not sufficient for lightning protection.

(2) The ugly round/solid aluminum wire hooked to a ground rod that was on the old antenna was probably acceptable since apparently you don't have a driven ground rod for your electrical service.

(3) Running it inside the house is very dangerous since a strike will be directed inside the house. A strike current will heat that #10 up to red hot and cause a fire inside the house.
telco_mtl
join:2012-01-06

telco_mtl

Member

said by Jack_in_VA:

said by alkizmo:

In my case, it is hooked up to the house's grounding system, which is the cold water copper pipe.

The OLD antenna has a bare round/solid aluminum cable that only went to a grounding rod. That cable was unflexible, thus uglily protruding from the cable path. I replaced it with braided 10AWG copper that clamps THROUGH the original ground rod and continues inside the house to the copper pipe

(1)Hooking it to the cold water pipe is not sufficient for lightning protection.

(2) The ugly round/solid aluminum wire hooked to a ground rod that was on the old antenna was probably acceptable since apparently you don't have a driven ground rod for your electrical service.

(3) Running it inside the house is very dangerous since a strike will be directed inside the house. A strike current will heat that #10 up to red hot and cause a fire inside the house.

I have to concur my neighbors look tv mast (look was a microwave based TV service here in canada) fell on a power line (nothing like lightning i know) and i will say they were more than thankful that the grouding on the mast was still there from when it was a mast for the regular tv.

alkizmo
join:2007-06-25
Pierrefonds, QC

alkizmo to Jack_in_VA

Member

to Jack_in_VA
said by tschmidt:

Assuming the antenna is some distance away from building ground then a driven ground rod at the antenna with antenna

Ok, the ground rod is already there.
said by tschmidt:

ground electrode and building ground bonded with 6AWG.

said by Jack_in_VA:

(3) Running it inside the house is very dangerous since a strike will be directed inside the house. A strike current will heat that #10 up to red hot and cause a fire inside the house.

You both say opposite things.
The ground electrode/rod cannot be bonded to the building ground unless the copper wire goes inside the house.
Or is the only acceptable way is to use AWG6 instead of 10AWG?

Can I use 10AWG from atenna to rod, and 6AWG from rod to copper pipe? (I still have enough 6AWG left over to do rod to pipe)
said by tschmidt:

The coax should pass through a grounding block where is enters the building and a gas tube coaxial surge suppressor at the ground block can't hurt.

What should the block be grounded to?
said by Jack_in_VA:

(1)Hooking it to the cold water pipe is not sufficient for lightning protection.

But what is the acceptable setup for residential antennas?
said by Jack_in_VA:

(2) The ugly round/solid aluminum wire hooked to a ground rod that was on the old antenna was probably acceptable since apparently you don't have a driven ground rod for your electrical service.

So you're saying that the antenna should be grounded to the rod, as long as the rod isn't bonded to the house ground?

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA

Premium Member

The ground rod should be tied to the service ground with a #6 copper conductor.

alkizmo
join:2007-06-25
Pierrefonds, QC

alkizmo

Member

said by Jack_in_VA:

The ground rod should be tied to the service ground with a #6 copper conductor.

Ok, so if my only modification is to change the 10AWG going from the rod to my pipe with 6AWG, would I be fine?

tschmidt
MVM
join:2000-11-12
Milford, NH
·Consolidated Com..
·Republic Wireless
·Hollis Hosting

tschmidt to alkizmo

MVM

to alkizmo
said by alkizmo:

You both say opposite things.
The ground electrode/rod cannot be bonded to the building ground unless the copper wire goes inside the house.
Or is the only acceptable way is to use AWG6 instead of 10AWG?

In the US the NEC (I assume there is a similar requirement in Canada) requires the antenna be bonded to building ground with 6AWG copper or larger. That is large enough to prevent it from being vaporized as Jack_in_VA See Profile posted.

If the antenna is any distance away from the main building ground the ground rod will dump most of the energy into the earth, minimizing how much flows in the bonding conductor. The ground rod must be bonded to antenna and building ground system.
said by alkizmo:

What should the block be grounded to?

The coax grounding fitting should be connected to the grounding conductor near where the coax entered the house.

Thinking about a water analogy might make it easier to visualize. You are trying to make it as easy as possible for water to get to Earth.

/tom
iknow_t
join:2012-05-03

iknow_t to alkizmo

Member

to alkizmo
said by alkizmo:

said by Jack_in_VA:

The ground rod should be tied to the service ground with a #6 copper conductor.

Ok, so if my only modification is to change the 10AWG going from the rod to my pipe with 6AWG, would I be fine?

you'd be much better off.. safer would be the word..

alkizmo
join:2007-06-25
Pierrefonds, QC

alkizmo

Member

said by tschmidt:

If the antenna is any distance away from the main building ground the ground rod will dump most of the energy into the earth, minimizing how much flows in the bonding conductor. The ground rod must be bonded to antenna and building ground system.

The antenna is on my roof, so it's not any distance of the building. The rod is about 2 feet from my exterior wall. I guess I may as well use the rod since it's already there though.
said by tschmidt:

The coax grounding fitting should be connected to the grounding conductor near where the coax entered the house.

I'm just having trouble seeing a coax grounding block being able to clamp a 6AWG stranded copper wire. Usually those things are made to clamp onto line drop masts.
said by iknow_t:

you'd be much better off.. safer would be the word..

The question was whether the 10AWG from antenna to rod also needed to be replaced.
I figure that wire can turn red hot without causing problems since it's outside.

tschmidt
MVM
join:2000-11-12
Milford, NH
·Consolidated Com..
·Republic Wireless
·Hollis Hosting

tschmidt to alkizmo

MVM

to alkizmo
said by alkizmo:

my only modification is to change the 10AWG going from the rod to my pipe with 6AWG, would I be fine?

This is where technical and legalese converge.

From an engineering standpoint connecting the antenna bonding conductor to copper cold water pipe is fine. Having larger surface area the pipe has a lower impedance then 6 AWG cable.

However: to be legally compliant the 6 AWG bonding conductor must run all the way to the building ground system. The reason is concern that in the future someone will replace a section of copper water pipe with plastic nullifying the ground.

/tom

alkizmo
join:2007-06-25
Pierrefonds, QC

alkizmo

Member

said by tschmidt:

However: to be legally compliant the 6 AWG bonding conductor must run all the way to the building ground system. The reason is concern that in the future someone will replace a section of copper water pipe with plastic nullifying the ground

The house ground IS the copper pipe.
The entry point of the copper pipe is drywalled, so I cant reach that anymore.

My alternative would be to bond at my electrical panel.

tschmidt
MVM
join:2000-11-12
Milford, NH
·Consolidated Com..
·Republic Wireless
·Hollis Hosting

1 edit

tschmidt to alkizmo

MVM

to alkizmo
said by alkizmo:

The antenna is on my roof, so it's not any distance of the building. The rod is about 2 feet from my exterior wall. I guess I may as well use the rod since it's already there though.

Sorry I'm confused. The issue is the location of the antenna relative to main building ground. Since there is already a ground rod in place use it AND bond everything together with 6-AWG. By code you can use 10-AWG for the mast, but need 6-AWG to bond ground electrodes together. Bottom line the larger the better, if it were my house I'd use 6-AWG to bond the mast.
said by alkizmo:

I'm just having trouble seeing a coax grounding block being able to clamp a 6AWG stranded copper wire. Usually those things are made to clamp onto line drop masts.

Where does the coax enter the house? If it is near the antenna mast bolt the coax ground block to the mast. If coax enters some distance away screw the ground block to the house where the coax enters and use some of your 10 AWG wire to bond the ground block to 6 AWG bonding conductor with a split-bolt clamp.

Here is a picture and an explanation.
»ecmweb.com/code-basics/a ··· quipment

/tom

Hellrazor
Bah Humbug
join:2002-02-02
Abyss, PA

Hellrazor to tschmidt

Member

to tschmidt
said by tschmidt:

From an engineering standpoint connecting the antenna bonding conductor to copper cold water pipe is fine.

Quoting engineers doesn't mean reality.

If you inspected the line and everything is metallic. Life is a bitch if you do that and some part of your supply run is plastic or hits an old transit supply line 40' in front of the house.

Don't assume.

robbin
Mod
join:2000-09-21
Leander, TX

robbin to tschmidt

Mod

to tschmidt
said by tschmidt:

In the US the NEC (I assume there is a similar requirement in Canada) requires the antenna be bonded to building ground with 6AWG copper or larger.

I thought antenna masts were to be bonded to ground with a minimum 10 gauge. 6 AWG is what is used to bond additional ground rods to the main electric ground. There should also be a 10 gauge bond to a lightning protector where the cable enters the residence. I would use 10 gauge for both bonds to the secondary ground rod and then 6 for a bond between ground rods. That would meet the requirements of the NEC.

In response to those who are debating the usefulness of this, please remember that this is not a lightning protection system. It is simple eguipment bonding to the electrical ground system as required for electrical safety.

shdesigns
Powered By Infinite Improbabilty Drive
Premium Member
join:2000-12-01
Stone Mountain, GA
(Software) pfSense
ARRIS SB6121

shdesigns to alkizmo

Premium Member

to alkizmo
said by alkizmo:

The house ground IS the copper pipe.
The entry point of the copper pipe is drywalled, so I cant reach that anymore.

Better to run it to the pipe outside rather than inside.

alkizmo
join:2007-06-25
Pierrefonds, QC

alkizmo

Member

said by shdesigns:

Better to run it to the pipe outside rather than inside.

wutchutaklingabout?
The pipe "outside" is something like 6 feet underground or more?

shdesigns
Powered By Infinite Improbabilty Drive
Premium Member
join:2000-12-01
Stone Mountain, GA
(Software) pfSense
ARRIS SB6121

shdesigns

Premium Member

said by alkizmo:

wutchutaklingabout?
The pipe "outside" is something like 6 feet underground or more?

With a strike, I would not want the ground wire inside my house when it vaporizes. I'd rather dig a deep hole than have it inside.
MaynardKrebs
We did it. We heaved Steve. Yipee.
Premium Member
join:2009-06-17

MaynardKrebs to Jack_in_VA

Premium Member

to Jack_in_VA
Flat copper braid is what's generally recommended for grounding in that situation.

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA

Premium Member

said by MaynardKrebs:

Flat copper braid is what's generally recommended for grounding in that situation.

Really? I've never seen it used for lightning protection applications. Even industrial is aluminum bare cable.
MaynardKrebs
We did it. We heaved Steve. Yipee.
Premium Member
join:2009-06-17

MaynardKrebs

Premium Member

It's for:
1) flexibility in installation in a residential setting, where the installer isn't working from a set of carefully engineered drawings and has a straight line path to the grounding point. A typical residential install will have many twists & turns, especially if done by a non-professional.
2) It's for contact area to quickly dissipate the current.
3) For heat dissipation reasons - see 2) above.

Similar attributes are why 'Ufer' - "Concrete Encased Electrode" (CEE) - grounds are preferred over ground rods or water pipes, but this has to be engineered from the start and you can't encapsulate a Ufer footing in waterproofing materials. There is really only one downside to CEE grounds and that's if the CEE ground system is in an area with high water tables - the concrete stays 'moist' enough that a lightning strike can cause residual moisture in the concrete to flash to steam - which can actually cause the building footings to crack.

»www.gacopper.com/Braid-S ··· son.html