Ground wire partly around the building is better than what
exists. However ground wire completely encircling the
building makes earth beneath building equipotential. That
Cinergy information says same. Three pictures (as I recall).
One is bad, very bad. Second is improvement. Third is most
IOW protection required is a function of geology and other
factors - best determined by neighborhood history. Typically
a potentially destructive transient occurs once every eight
years. How often does the neighborhood suffer a lightning
strike? If a few events (even to trees) have occurred in the
past decade, then consider a full halo ground.
But an earthing wire only part way around building and
connecting to all incoming utilities is a major improvement
over what you now have. Major improvement, I say, again.
Running a ground block to one point then using that
connection to make the earthing connection? It comes back to
a simple question. How many feet from that incoming wire,
connecting to other wires, then all way back to central ground
point. Add more feet for every sharp bend and splices. If
those wires are bundled with other wires, (ie safety ground
wire in romex), then that is more system compromises.
Distance from incoming utility wire to single point earth
ground must be 10 feet or less for effective transistor
Same applies to a ground on water faucet. Important is not
distance from incoming wire to faucet. Significant is
distance from incoming wire, through all those pipes, and then
on connecting wires (if they exist) to single point earth
ground. Again, soldered pipe joints and 90 degree turns in
that copper pipe only add more feet to that distance.
Do if only for human safety. You must get all those widely
separated grounds interconnected.
Also, repeating a previous post for the benefit of all,
measuring conductivity with meter (ie <1 ohm) does not prove a
good ground. Meter can only detect a bad ground; not prove a
good ground. Same for those three light receptacle testers.
They too can identify a defect. They cannot prove an outlet
is properly or sufficiently safety grounded. Repeated here
only because it demonstrates that logic process (thinking
binary instead of ternary) can lead to incorrect conclusions.
Important - you entered this with appropriate attitude.
Bonding all electrical services and safety grounding all metal
pipes is important, first and foremost, for human safety.
Human safety is your most important objective.
Minnie Bannister wrote:
Minnie Bannister wrote:
> I wrote:
>> I understand that the NEC requires that all grounds (e.g., lightning
>> protection grounds and grounds for radio transmitting equipment) must
>> be bonded to each other and to the utility company's ground. The
>> books I have read say this is accomplished by connecting everything
>> to the ground "at the service entrance panel." But how is this to be
>> accomplished? By clamping the ground conductors to the conduit (after
>> cleaning it down to bare metal) that comes out of the ground and up
>> to the meter on the wall of the building? By bringing the ground
>> conductors through the wall of the building and into the panel and
>> there connecting them to the existing ground bus? Or . . . ?
In order to do a fully safe install on your tower you will need to bond
those communications grounds to the electrical service ground. You
accomplish that by running a number six copper conductor from a clamp on
each rod to the other rods. The wire can pass through the acorn clamp
without any break so you can run one wire to all of the rods one after
another. The code does not specify what pathway to use when bonding
those different electrodes together but I have always tried to keep the
bonding conductor outside the home.
By far the best way to bond the different rods together would be to
install a ground ring. A ground ring is defined as a "ring encircling
the building or structure, in direct contact with the earth, consisting
of at least 6.0 m (20 ft) of bare copper conductor not smaller than 2
AWG." The code requires that "The ground ring shall be buried at a
depth below the earths surface of not less than 750 mm (30 in.)."
copyright 2002 National Fire Protection Association. I know that
installing the ring all the way around the structure is a lot of work
but if you just choose the side of the house were it will be easiest to
trench and do it on that side it will still have more than 20 feet in
the earth. Because ground rings provide much more surface contact they
are a much better grounding electrode than the common eight foot driven
If you cannot bring yourself to trench for a ground ring then you will
need to run the number six bonding conductor through, on, or around the
house to bond the different electrodes together. If you bury it the
code requires it to be twenty four inches deep unless it is in conduit
so you might as well go down thirty inches and run the larger wire to
get the benefit of a ground ring.
If you have underground metal water piping that is connected to a
municipal water system or a metal well casing it makes a very good
If you have a metal well casing, that you can run a bare number four or
two copper conductor to, the depth of the well makes it an excellent
If you end up pouring a concrete base for your tower be sure to bond any
reinforcing steel and the base anchor bolts to the grounding electrode
system. The reason that most folks put in a tower is to get the antenna
above local signal obstructions but that also makes the installation
lightning bait so be very careful about your grounding. You can order
ground rod couplers at any electrical supply house. You then rent a
demolition hammer and a ground rod cup to drive the coupled rods to an
effective depth. Three to four eight foot rods coupled together will
usually get the impedance under ten ohms.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.