Advice for grounding antennas

[miguelaqui]

I have 3 antennas on my roof. I have one grounded with a #10 stranded wire to the main ground of my house.

I am planning on grounding the other 2 as well, however, my house is close too 40 years-old and the main ground is on the main water line, not on a ground rod.

I do realize that the code calls for connecting the grounding for the antenna be connected to the main ground for the house, however, I am concerned that, should lightning ever hit one of the antennas, it would run in on my house grounding and cause serious damage. I have seen lightning come in on the ground of a house and messed up a lot of things.

Would it be just as good to drive a rod into the ground for the antennas only?

The only reason why I ask this is because, during my time as a CATV teach, I remember getting shocked when disconnecting some drops because the CATV ground was stronger than the ground at the house; I am afraid that I could possible create the same issue, sending electricity over the shielding go the coax.

Or, would it be best to ground the coax to the main house ground and the antenna masts to a rod?

 

[harshness]

You should keep looking. There should be at least one rod on homes built in the last 60 years or so. I suppose the "rod" may actually be a pipe driven vertically into the ground.

It should be within a few feet of the meter.

If you decide that you want to pop for a new conventional rod, copper clad is the rod of choice as it lasts much longer than galvanized rod (probably 3 times as long).

http://www.ecmag.com/section/safety/dirt-ground-rods

 

[Titanium]

It is more dangerous with the potential to cause more damage by placing additional grounding rods, UNLESS the grounding rods are bonded. Failure to bond separate grounds may cause a 'voltage potential" between the grounding points.

Voltage potentials are voltages that flow between the grounding points and can create noise in the system, damage electronics and in a worse case scenario injury (or death, though the chance of that is very low...). Have observed voltage potentials causing switch, amplifier and splitter failures, humming noise in the audio, rolling bars in the video, etc.

 

[FaT Air]

Are they on separate tripods? The coax runs where/how?
If they are on the same pole/tripod, they all are grounded to each other. and therefore your your house ground.

The electrical ground here starts at the electrical entry on one corner of the house, and runs within the basement stapled to beams holding up the main floor, to the water supply pipe at the opposite corner of the house. Electric is underground, house to the pole. (musta met code in '67)
Sure, it protects the electrical supply, but it's worthless trying to protect from lightning. IMHO
There was a lengthy thread a while ago concerning lightning grounding. Think it was in the FTA section. But I'm unable to find it. If I do find it later I'll post a link.

In the meantime, I use and recommend any antenna coax, phone wires, anything entering the premises that conducts, place a two or three turn loop in it between the ground block and its entrance point. Connect the ground block to your house ground. Keep that as straight as possible. Any corners make 'gentle'.
I've lost nothing to lightning. Even when the mighty Oak tree 40 ft from the house got hit. It died. Trunk was around 12 ft around.

 

[. Raine]

I don't know about the antenna grounding, but I'd be concerned about the house electrical being grounded to a water main. Lightning is very good at following metal pipes, you could have more serious issues from that than from your antennas involving lightning, not to mention other safety issues. If power somehow crosses over to your ground, your water system could become electrified, not good if you're taking a shower or such. Other issues could arise from that too and insurance won't pay out for a lot of things when the house isn't grounded properly.

As Harshness said, there should be at least one grounding rod, code now is to have two. I'd look that over better and if there is no true grounding rod for the house, I'd fix it.

 

[miguelaqui]

I swear ..there is no grounding rod at my house. The ground the comes in from the pole is bonded with a wire that is connected to the main water pipe.

I already have a bad ground loop issue here, to the point that I had to put 3 prong adapter on all devices connected to the CATV or satellite lines. I put an isolator on the CATV line, but they will not work with satellite. I thought it would be safer to put on the adaptor to defeat the ground than to disconnect the ground from the satellite dish.

The reason why I was thinking it was better to have a separate ground for the the antennas was that I once saw lighting hit a tree, which followed a root that was touching or near the house's ground rod. This caused the lightning to run in on the neutral side of his entire system, damaging a lot of stuff in his house. I only noticed this when I was replacing a melted receptacle and saw that the white wire was black.


This is why I thought that grounding the masts to a rod and the coax to the house's ground might be best? However, it look like my best bet is to drive a rod near the meter, and then connect the ground from the house to the rod as well? I am not going to drive a 12 foot rod, but I am willing to get one or more of the 4 foot ones.

 

[LightbulbGE]

I fully believe you, others are probably in areas with newer homes or earlier local codes which were naïve at best. Most older homes used water pipes for grounds and this worked well when all the pipes were new and all metal (copper or galvanized) I did a lot of ground testing on industries and utilities over the years and since I had access to ground meggars and the other equipment (test rods & connecting wires) I always tested my own homes also. I found and fixed a few problems. One of those was a power company ground on a power pole feeding my home. I detected that their ground on their transformer was no longer connected.

There is not problem with taking the grounds from the masts of your antennas, external to the house structure to a separate ground external to the home. This will protect the building structure the same as a lightening rod will. The problem is that if this ground is not tied to the existing ground of the electrical system of the home is that there could develop a difference of potential (volts) beteen the two grounds and since one would be on the antenna wire and one on the AC plug in, equipment or personnel damage could occur (as in death)

Personally, I would probably do a grouping of ground rods to lower the ground resistance. A group of 3 spaced 5 feet apart and bonded together to act as one would give much lower ground resistance. That should be in the yard, not under the house and should have a single lead connecting it to the electrical grounds in the house and this should be considered your primary ground. The water pipes should also be connected so you have only one ground acting and of course that should be connected to all electrical grounds in home. If you stay with pipe grounding, I cannot say whether it will meet current code in your area and whether your home would be safe without testing which is rarely done for homes. A single ground rod is usually not good enough and is usually not as good as the old pipe grounding system but it meets code in most areas and is all most homes have.

Definitely connect your antennas to the best ground you have and I would prefer to see external grounds rather than through the building. A lighting strike is very powerful and the small wire (you said #10) will likely vaporize, with the full amperage of the strike following the ionized air to ground. The other thing to ground is your coax cable through special m-m connectors with a connection provided to connect to grouind

 

[harshness]

Grounding to the house ground when the house isn't properly grounded probably isn't a win.

Much of what grounding is for is to drain off stray currents that happen as a result of static; not so much to protect from lightning. If you remember your Ben Franklin teachings, grounding something elevated typically attracts lightning.

 

[miguelaqui]

Grounding to the house ground when the house isn't properly grounded probably isn't a win.

Much of what grounding is for is to drain off stray currents that happen as a result of static; not so much to protect from lightning. If you remember your Ben Franklin teachings, grounding something elevated typically attracts lightning.

I agree. That is why I never believed that grounding a satellite dish that was on the roof was a good idea. I just wanted to make sure that, should lightning hit it , it would be less likely to burn my house down.

 

[miguelaqui]

I fully believe you, others are probably in areas with newer homes or earlier local codes which were naïve at best. Most older homes used water pipes for grounds and this worked well when all the pipes were new and all metal (copper or galvanized) I did a lot of ground testing on industries and utilities over the years and since I had access to ground meggars and the other equipment (test rods & connecting wires) I always tested my own homes also. I found and fixed a few problems. One of those was a power company ground on a power pole feeding my home. I detected that their ground on their transformer was no longer connected.

There is not problem with taking the grounds from the masts of your antennas, external to the house structure to a separate ground external to the home. This will protect the building structure the same as a lightening rod will. The problem is that if this ground is not tied to the existing ground of the electrical system of the home is that there could develop a difference of potential (volts) beteen the two grounds and since one would be on the antenna wire and one on the AC plug in, equipment or personnel damage could occur (as in death)

Personally, I would probably do a grouping of ground rods to lower the ground resistance. A group of 3 spaced 5 feet apart and bonded together to act as one would give much lower ground resistance. That should be in the yard, not under the house and should have a single lead connecting it to the electrical grounds in the house and this should be considered your primary ground. The water pipes should also be connected so you have only one ground acting and of course that should be connected to all electrical grounds in home. If you stay with pipe grounding, I cannot say whether it will meet current code in your area and whether your home would be safe without testing which is rarely done for homes. A single ground rod is usually not good enough and is usually not as good as the old pipe grounding system but it meets code in most areas and is all most homes have.

Definitely connect your antennas to the best ground you have and I would prefer to see external grounds rather than through the building. A lighting strike is very powerful and the small wire (you said #10) will likely vaporize, with the full amperage of the strike following the ionized air to ground. The other thing to ground is your coax cable through special m-m connectors with a connection provided to connect to grouind

How about this...taking 3 of the small 4 foot rods, running the number #10 from the antenna to the rods directly. Taking a #8 and running it from the wire that leads to the pipe, it is right outside at the meter, and bonding the ground from the rods to the house and electric company ground? Would that take care of any potential problems while reducing the potential of , should lighting hit the antenna, of bringing it into my home? I have 3 of the 4 foot rods on the way; I really cannot get an 8 foot rod into the ground, at least not by myself.

 

[harshness]

I just wanted to make sure that, should lightning hit it , it would be less likely to burn my house down.

As was pointed out by LightbulbGE, lightning will vaporize the wire unless it is rather large so burning down the house is unlikely. The question is how much current is carried before the wire turns to gas.

IIRC, bonding wire (that which is used to add ground rods to an existing array) is specified as #6.

 

[. Raine]

I think Harshness is right, # 6 wire for bonding. Two 8' foot ground rods 6' apart is code now, I think, but the only way to be sure would be to ask a licensed electrician in your area. As far as having your house's main ground being a water pipe, that can be bad. I believe you saying that it's that way, especially if the house is old, but it can be a very bad deal.

The pipes typically will be bonded to the structure ground, in case a bare wire lays across a pipe, lightning, etc, so dangerous voltages won't be present in the water system if anything does happen, the current will be diverted to the main ground and trip a breaker. Water pipes shouldn't be the structure's main safety ground though. A water main as a ground may work, [emphasize may] but along the pipe there will be unions that may cause you to lose your ground, the soil conditions around the pipe, if it's not deep enough, if the connection to the pipe isn't the right type of clamp and corrodes, quite a few things can cause that type of setup to go south. Lightning, or other introduced voltages could follow that pipe into your house and have nowhere to go, with no real structure ground and may not blow a fuse/pop a breaker, in that case. My house here had horrible wiring when I first bought it, it was built in 1938, I re-wired it and had a electrician install 100 A service and proper grounding. Too much bad stuff can happen with faulty electrical. I'm not a electrician, so I could be all wet on this, but I myself, wouldn't be comfortable with that setup.

 

[miguelaqui]

8 foot rods are too hard to install! I bought some 4 foot rods that I plan on using to ground the antennas, running the #10 to rod #1, the connecting rod 1 to rod 2 with #6, and then connecting rod #2 to the main ground with #6 copper wire.

As far as having my house inspected.. I don't have the money to have it all redone.

As far as my house ground..I have always been told that it was just for a backup? Isn't the power company's ground the main one?

I do have another question... the reason why I want to run #10 is that it is insulated. I have an aluminum siding house and do not want the antennas' ground coming into contact with the siding. Also, I have read that #10 is code for grounding of antennas. However, I would consider running to lines of #10 to the ground rod. Would that make a difference? It is my understanding that AC would simply choose one of the 2 lines, the one with the least resistance, and go down it.

 

[harshness]

If you're not going to do it right, sometimes it is better not to do it at all. Grounding is not a matter of more is better. It is a system that must be carefully balanced so that you protect what you want to protect without creating a lightning rod. You don't get to pick and choose specifications to meet your budget. Doing so will give you false sense of security.

Most house wire insulation is only good for 600 volts so expecting it to handle a major zap is folly. The wire insulation combined with whatever dielectric value the paint on the siding offers won't make any appreciable difference if lightning is the voltage source.

#10 is what is required from the coaxial grounding block to a bonding point and the grounding block is a second line of defense after the mast ground. The messenger wire in coaxial cable is #17 and that's what is often used to ground the mast. That ground coupled with the coax grounding block must not be so large as to swamp the line to the bonding point.

 

[FaT Air]

From my experience, most so called 'lightning damage' isn't from a direct strike.
Most is caused from an induced pulse of voltage via EMF.
A current, say the lightning strike following some path to ground, parallels some conductor carrying AC power to your home.
This could be close, in your neighborhood, on your property, or many miles away along the power line. The closer the strike, the greater the induced voltage pulse on the power line.
No grounding that could be done on your property will protect from this. But there are ways to minimize it's chances of taking out any of your electronics.
A 'Whole House Suppressor'
To back that up one can employ quality power strip suppressors AND run all power, phone line, and coaxes through it. Put a 3 (or more) turn loop in the wires that run to your equipment from the power strip. Be sure to have the power strips power cable straight to the outlet. ( See note)
BTW: I don't have the 'whole house suppressor' but do the backup alone.
I rely on the 'cone of protection' offered by taller structures near the house. The closer, and the grater the ratio of height, the more effective this is.
Haven't had a strike on the property in 20+ years, but the one then, took out an oak tree about 40ft from the closest point of the house.
The oak was about twice the height of the house. Nothing was damaged in the house. (this yr, since May, has had more than a normal number of severe lightning storms, but there's more trees, and they are taller now.)
IMHO, if the house were covered with lightning rods, it could have attracted the strike away from the oak, and saved it.

FWIW: When I employed the loops on 300 ft radio towers, on 2 - 300 ft buttes, in Western N.D. eastern MT. , just before the lines entered the radio cabinets. Lightning service calls went from a dozen a month to about 1 call in three months. /FWIW

If the local area has many reoccurring direct lightning strikes, chimneys blown apart, metal siding burnt and scattered on the lawn, etc. I'd do extensive grounding for lightning. NEMA guide lines fall far short in this area IMHO.
Wish I could find that thread as there is a very valuable link in it detailing effective lightning grounding while conforming to NEMA.
NEMA guide lines are more concerned with preventing a strike from entering the power grid from a strike on your property, IMHO.

note: reason they say NOT to 'take cover' close under that tree.
The tree is the most likely to get the strike. (It's tallest thing in the area) if the strike doesn't jump from the tree to you, and the ground you're standing on doesn't get 'charged, your body will still be the 'parallel conductor'. You're safer [IMHO] sitting on the ground, 2/3ds the trees height, away from it.

Harshness: I think he went insulated to minimize/eliminate the effects of electrolyses from discoloring the siding.-

 

[bcwmachine]

NFPA 780: Standard for the Installation of Lightning Protection Systems