System ground question

[delta_p]

Is it ok to run a copper ground wire under the house to complete the ground system?

The ARRL Antenna book recommends a ground system for safety and RF as tying everthing together with a copper wire loop around the house. I have my radio room on the front my house with the antenna outside on a tower in the backyard. Currently, I have my tower grounded with three 8ft rods in delta shape around the base and all tied together with awg 4. Then from here, a 50 ft run up to the house where the coax enters the crawl space through a vent. I have one rod in the middle of this 50ft run and one at the end near the house also tied together and to the tower rods with awg 4. I have the coax grounded to the rod near the house.

Then, on the front of the house I run about 6ft through the wall to an 8ft rod in the flower bed and I tied this rod to the ac/phone ground rod. The equipment is grounded here where it penetrates the wall into the room.

I do not have the ground system in the backyard tied to the system in the front yard and am wanting to just run some copper through the crawl space instead of all the way around the house. Comments on this method would be appreciated.

What is the purpose of the loop around the house anyway?

PP

 

[OceanaRadio]

Is it ok to run a copper ground wire under the house to complete the ground system?

The ARRL Antenna book recommends a ground system for safety and RF as tying everthing together with a copper wire loop around the house. I have my radio room on the front my house with the antenna outside on a tower in the backyard. Currently, I have my tower grounded with three 8ft rods in delta shape around the base and all tied together with awg 4. Then from here, a 50 ft run up to the house where the coax enters the crawl space through a vent. I have one rod in the middle of this 50ft run and one at the end near the house also tied together and to the tower rods with awg 4. I have the coax grounded to the rod near the house.

Then, on the front of the house I run about 6ft through the wall to an 8ft rod in the flower bed and I tied this rod to the ac/phone ground rod. The equipment is grounded here where it penetrates the wall into the room.

I do not have the ground system in the backyard tied to the system in the front yard and am wanting to just run some copper through the crawl space instead of all the way around the house. Comments on this method would be appreciated.

What is the purpose of the loop around the house anyway?

PP

Delta P,

A complete ground ring, and to a lessor degree any outside grounding field, provides maximum dispersal area to dispel energy from a direct attachment of lightning to the structure which it surrounds.

Maintaining the most efficient equipotential between all grounding systems is certainly a primary goal when designing any outside grounding system. However a nearby strike allows ground fields to bring unwanted energy INTO a structure and attached equipment. That is one reason why the single-point ground connection at the equipment is critical, so the equipment will rise and fall in potential together and not have alternate paths of ingress or egress with differing potentials. Bonding at least one point of the outside tower grounds to the AC/Utility entrance ground is the primary protection from one form of undesireable exit-paths through your equipment. Surge protection at the AC/Utility entrance is also required, much the same as coax surge arrestors are required on feedlines. Minimizing the insult to equipment from lightning must be done on all sides of the equation.

I used under house crawlspace area as the shortest-distance to bond the equipment room single point ground connection to the AC/Utility ground rod at the other end of the home. Due to the available height of the crawlspace, I was able to sink several 4' ground rods along that bonding conductor. There is also a semi-circle of buried outdoor bonding conductors that tie all outdoor coax shield grounds, the equipment room single point ground, and the AC/Utility ground rod together. I saw no added benefit to sawing driveway concrete in order to complete the other half of what would have then been a complete ground ring. Then again neither my home or antennas are subject to a primary (direct) attachment to lightning as I am surrounded by 100' tall pine trees. The trees are struck frequently however, and four of them hold HF wire antenna systems.

Besides the crawlspace bonding conductor you proposed, the other addition I would suggest is that you shield-ground all coax right at the base of your tower. It sounds like you have a well planned and resilient system. For the part that's always left to chance, I'll add "good luck".

Jack

 

[delta_p]

Delta P,

A complete ground ring, and to a lessor degree any outside grounding field, provides maximum dispersal area to dispel energy from a direct attachment of lightning to the structure which it surrounds.

Maintaining the most efficient equipotential between all grounding systems is certainly a primary goal when designing any outside grounding system. However a nearby strike allows ground fields to bring unwanted energy INTO a structure and attached equipment. That is one reason why the single-point ground connection at the equipment is critical, so the equipment will rise and fall in potential together and not have alternate paths of ingress or egress with differing potentials. Bonding at least one point of the outside tower grounds to the AC/Utility entrance ground is the primary protection from one form of undesireable exit-paths through your equipment. Surge protection at the AC/Utility entrance is also required, much the same as coax surge arrestors are required on feedlines. Minimizing the insult to equipment from lightning must be done on all sides of the equation.

I used under house crawlspace area as the shortest-distance to bond the equipment room single point ground connection to the AC/Utility ground rod at the other end of the home. Due to the available height of the crawlspace, I was able to sink several 4' ground rods along that bonding conductor. There is also a semi-circle of buried outdoor bonding conductors that tie all outdoor coax shield grounds, the equipment room single point ground, and the AC/Utility ground rod together. I saw no added benefit to sawing driveway concrete in order to complete the other half of what would have then been a complete ground ring. Then again neither my home or antennas are subject to a primary (direct) attachment to lightning as I am surrounded by 100' tall pine trees. The trees are struck frequently however, and four of them hold HF wire antenna systems.

Besides the crawlspace bonding conductor you proposed, the other addition I would suggest is that you shield-ground all coax right at the base of your tower. It sounds like you have a well planned and resilient system. For the part that's always left to chance, I'll add "good luck".

Jack

Jack,
Thanks for your comments. I always like reading your posts on grounding since you always seem to know so much about it. How is coax shield grounded? Isn't it already grounded through the ground lug off the lightning protector in line with each coax?

PP

 

[OceanaRadio]

Jack,
Thanks for your comments. I always like reading your posts on grounding since you always seem to know so much about it. How is coax shield grounded? Isn't it already grounded through the ground lug off the lightning protector in line with each coax?

PP

PP,

Yes, when the arrestor is grounded it does provide one coax shield grounding at that point. However it is important to have shield-grounded the coax prior to that point as well. One other place that occurs without special effort is where a DC-grounded antenna mounts to it's suport-body which is then clamped to a mast or tower. The coax connection at the antenna-support does form a shield ground right there. Because you have a tower, I recommended you add a shield ground at the base of the tower. Specifically, this is best accomplished immediately after the geometry of the coax turning toward the home/structure. Harger or Andrews Wire for example carry coax shield grounding kits that affix to the coax where an inch or so of outer sheath has been removed with a knife. All industry recommends this coax shield ground at the base of the tower. If towers are more than 100' tall then additional shield grounds are specified at top, center and bottom, or every 100' of the tower for very tall units. I 'm not sure that extra tower-base shield ground will make or break your system, but the ICE protectors that I believe are the best do require that shield grounds be present (upstream) for the protector to function as it is guaranteed. If it were mine I would add it, I'll leave it at that.

Jack