[RFI] Station ground - more

[Jim Brown]

On Tue,10/4/2016 12:59 PM, Kenneth G. Gordon wrote:
> On 4 Oct 2016 at 12:50, Jim Brown wrote:
>
>> Not quite.  What must happen at the "Main Panel" is the bond between
>> Neutral and Equipment Ground. That bond MUST be done where power enters
>> the building, and it MUST be the ONLY connection between Neutral and
>> Ground anywhere in the system.
> Ah HA! Finally! Someone gets to the crux of the matter in simple language. Thank you, Jim.

Thanks. BTW -- ALL of this is in the set of Power Point slides for which 
I've posted a link here at least a half dozen times. :)

>
>> There must also be an Earth Connection
>> (that is, a driven rod) at that point. ANY building can have as many
>> EARTH connections as you like, and they can be connected to the "Green
>> Wire" ANYWHERE you like, but they MUST all be bonded together.
>>
>> "Equipment Ground" in the context of power systems is the steel
>> enclosures of electrical panels, and of the "Green Wire" throughout the
>> building.
> One last question: I assume that #10 bare wire is NOT large enough to bond all ground
> rods/systems together? What size would you suggest?

A "bond," by definition, is "a mechanically robust, low impedance 
connection that is capable of carrying any fault current that may be 
occur." Worst case, that's lightning, so we'd like the conductor to be 
large enough to carry the discharge without melting. Obviously, that 
depends on how close the hit is, but larger is better. :)  As to 
impedance -- remember that lightning is an RF event, NOT a DC event, so 
impedance is dominated by inductance. This dictates that "shorter is 
better."  My bonds between earth electrodes are #4 stranded copper. In 
large buildings, AWG #00 or #0000 is often used.

73, Jim K9YC