[RFI] grounding your ham equipment
erik at n0ew.org
erik at n0ew.org
Sat Jul 29 12:41:18 EDT 2006
> now on my ham station equipment what is the best way to ground
> tuner, radio etc to my station to my ground rod. to avoid ground
> loops do i use tuner as my central and ground all ham gear to my
> tuner and then to grounding rod outside. th use copper strap or
> braided strap from ham gear to tuner and then to grounding rod
> .thanks. kx3x
1. National Electric Code (NEC) has all the info you seek. And it
makes for fun reading too!
2. If in doubt, hire an electrician. (No, I'm not a union electrician, hehehe)
3. "Polyphaser" has a very in depth PDF (?) on this subject, as well
as the subject of lightning protection. It'll tell you more than I
can. Here is where to find links to their various technical papers:
I'd certainly recommend at least reading: "TD1023" "TD1016" "TD1019"
4. My info is derived largely from the above sources as well as a
series of ham radio club meetings given by a local company that
installs 2-way radio systems and towers. It comes from memory. I
haven't reread any of the above suggested sources of information. I
recommend you do so.
5. You've heard this before! "Your mileage may vary." I'll add, don't
just belive what anyone tells you. Consider their advice but do your
own research to find out if you agree. There is nothing wrong with
asking for directions, but do a little fact-checking before jumping
off that bridge!
IN YOUR SHACK:
Buy a piece of copper pipe. Or much more expensive, buy an electrical
grounding buss from an electrical supply company. I use a 1/2-inch
diameter copper pipe, about 5-foot long. I have suspended it below the
bottom shelf that sits immediately above my operating desk. It should
be attached with non-conducting brackets if attached to something like
a metal desk.
Each piece of equipment should have its OWN short length of grounding
wire attaching the piece of equipment to the copper pipe. You can buy
official grounding straps that are made up of many strands of metal
woven into a braid. These come in a variety of widths, from 1/2-inch
up to 2-inches. Some people use old coax and separate the braided
shielding from the rest of the coax. Either way should be OK. You can
also get copper or brass sheets of metal and use these in place of the
braided metal. Home repair stores may sell such metal strips as insect
barriers or as flashing material.
So... each individual piece of equipment now has a length of metal
attaching it to the copper pipe.
The copper pipe then has a larger width piece of metal connecting it
to a nearby ground rod. Some peole use the 1/2-inch brain to connect
the individual pieces of equipment to the copper pipe, and then the
larger 2-inch braid to connect the copper pipe to the ground rod. (I
_don't_ know if the braid will survive the Cad-Weld.) Some people will
use a large diameter wire, something like #2: big thick stuff! It'll
cost high per foot, but if you are only going to a short distance out
your closest window, the total $$$ spent isn't that great. Nothing
smaller than #6 bare copper wire, which all electrical supply houses
will have in stock (they'll have the #2 as well).
Many people set a new grounding rod outside their ham shack window.
This is OK provided you also follow the "outside" steps below.
Find an electrical supply house. Ask for "Cad-Weld" or if they don't
have that, ask them what they have to attach two dissimilar metals to
one another on the ground rod. This stuff gets incredibly hot!
Volcano-hot! Follow the directions exactly, and if in doubt find an
electrician friend to help. If you don't have a friend who's an
electrician, hire one.
The point is that merely screwing a set screw against the wire running
from your copper pipe against the grounding rod isn't a very good
connection. Over a very short period of time it'll become dirty,
corroded, and otherwise not very effective.
Around here the Cad-Weld is something like $15 per use. Expensive,
seemingly, but it gets the job done correctly. Did I mention it gets
incredibly hot? Hotter than the sun hot? In this case the saying is
true: "Be careful - it's hot!"
OUTSIDE THE SHACK
If you leave the ham shack ground rod isolated (meaning unconnected to
all the other ground rods outside, which are connected to your home's
electrical system) you are setting your ham shack up for damage. There
then exists "potential differences" between your shack and the rest of
When an electrical surge takes place the voltage difference to ground
will be different at your station as compared to the rest of the
house. This causes current to flow, and you have effectively directed
a flow of current through your nice expensive ham radio equipment. You
may end up letting the smoke out, and as we all know, all electronic
devices are powered by smoke. If you let the smoke out they cease
This is corrected by daisy-chain connecting all outside ground rods.
Or run individual grounding wires, that part doesn't matter (other
The point is this:
All outdoor ground rods must be connected to the main utility ground rod.
The main utility ground rod is normally close to your main breaker
box. If you live in a more rural area this may be where the drop comes
from the utility company to your electrical pole (such is my case).
These outdoor ground rods should be connected with no smaller than #2
wire. (Ouch! $$$!) Some people skimp and use #6. Anything of smaller
diameter is likely to be a waste of money. I've never heard a pro
actually recommend using #6. They usually either say "No" or they
sadly shake their heads. If you know them well, and press them, you
might get them to begrudingly say you can go ahead and use #6 wire,
but only it you don't act suprised when it vaporizes: In other words,
if you're too cheap to do the job right, don't be surprised when your
equipment, or home, goes up in a puff of smoke!
There you go. My 2-1/2-cents!
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