More Bonding is indeed the answer. It is not only required by the NEC but
it is also safer. For instance, if a nearby lightning strike affects some
grounds more than others (because they are NOT bonded) then a large
potential can be caused to exist and to flow through equipment - and ruin
it. That is all quite aside from buzz and hum.
As far as buzz and hum are concerned - remember that the leakage signals
will be small in amplitude. Thus their I2R losses will be quite low. This
is especially true if VERY large bonding conductors are used (small R).
Obviously you cannot have the distance as small as you would like. So
impedances will rear their ugly heads. No help for that. But even there,
arrange the very best bonding connection that you can, in order to minimize
the problem to the extent practical.
Even an imperfect bond is an improvement, as Jim has pointed out now, and
many times in the past.
73 de Gary, AA2IZ
----- Original Message -----
From: "Don Allen" <firstname.lastname@example.org>
Sent: Monday, January 23, 2012 6:42 PM
Subject: [TenTec] Re. [Ten Tec] Grounds
> What Jim says is true, but sometimes - as in my case - it's a bit
> difficult to put into practice. My station is located in a finished
> basement with a series of ground rods at ground level approximately 10
> to 12 feet from the operating desk position connected with #0 wire.
> However, the service entrance box from the buried electrical is located
> at least 50 feet from the operating position. And, due to the location
> of the electrical utility's ground rod, I can't get to it as it's
> beneath our deck. Yes, the electrical utility installer placed it in
> that location. My only option is to run a fat copper wire to the ground
> at the service entrance box to bond the grounds together. My next door
> neighbor is a licensed union electrician, and he would likely be the one
> to tackle the job. However, due to the distance, I'm concerned with the
> inductance due to the length required. I suppose the best choice would
> be to locate one's shack directly within a short range from the service
> entrance box/breaker box, but for the vast majority of us, this is
> impractical. I'd have to kick my XYL out of our basement's laundry room
> (the location of the breaker box) to convert it into a ham shack!!
> Interestingly, our previous house which was built in the '50s, did not
> have 3-wire distribution and grounded outlets. I never experienced any
> buzz or hum with any rigs at that location. Here I do, most likely due
> to what Jim described below. I also have tons (constant S6 to S7) noise
> levels from the neighbor's plasma TVs, and the crappy above ground power
> lines here. Our local electrical utility is strapped for cash, and they
> don't want to hear about leaky insulators, even if it's costing them
> distribution efficiency or problems.
> Don W9CW
> From: Jim Brown<email@example.com>
> Sent: Sunday, January 22, 2012 1:03 PM
> Subject: Re: [TenTec] grounds
> It is also VERY UNSAFE, is a violation of all building codes, and
> provides no benefit.
> A difference in potential exists when all grounds are NOT connected.
> The rule, both for safety and best noise immunity (including hum and
> buzz and RFI) is really quite simple. You may have as many ground
> connections as you like, but they MUST be bonded together, and the
> connections should be fat copper, as short as practical.
> The concept of a "ground loop" is a fiction.? The REAL cause of hum and
> buzz from the AC power system are LEAKAGE CURRENTS that are the result
> of capacitance between the Phase ("hot") conductor and the green wire
> (protective ground).? Those leakage currents flow in the green wire, and
> the resulting IR drop causes a "buzz" voltage to exist between equipment
> plugged into different power outlets, and to equipment that might be
> GROUNDED better than, or separately from where the AC power line is
> grounded.? That difference voltage is greatly reduced by properly
> BONDING all those grounds together.
> We HEAR that buzz on unbalanced connections between equipment because
> their chassis are at different AC voltages (due to the IR drop from
> their leakage currents).? These are not "ground loops," they are simply
> LEAKAGE CURRENTS, and they are added to the signal because they are in
> series with the signal.
> The concept of a "ground loop" is simply WRONG -- more bonding is
> BETTER, and is the SOLUTION, not the cause!
> 73, Jim Brown K9YC.
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