Only ONE neutral - ground bond allowed. Only at the MDP; all sub-panels
must have the neutral - ground bonding screw removed, then supplemental
grounds may be applied.
73 ES DX,
Gary - AB9M
On 9/28/2016 12:19 PM, Jim Brown wrote:
> On Wed,9/28/2016 9:37 AM, Kenneth G. Gordon wrote:
>> For instance, when I was wiring our new addition, the wiring included
>> a sub-panel,
>> connected to the main panel by a run of #00 4 wire cable. With the
>> assistance of our
>> youngest son, we drove an 8' ground rod directly under the sub-panel
>> with the thought that I
>> had to connect that to the sub-panel's ground lug.
>>
>> Yet I was told by the electrical inspector that this was NOT allowed,
>> but that we had to run a
>> separate ground wire from the sub-panel at least 30 feet to the
>> main-panel's ground lug and
>> connect them together there.
> He's partly right and partly wrong. Under the current NEC, you MUST
> carry ground from the main panel. Under older versions, (10 years or
> more) you did not need to carry ground between two buildings (but you
> MUST carry ground everywhere in the same building). Where he's wrong
> is that you can ADD as many grounds ANYWHERE and connect them to the
> equipment ground (the green wire, which MUST be bonded to the
> enclosure of every electrical enclosure) ANYWHERE in the building.
> Fundamental rule -- you can have as many grounds as you like, but they
> MUST all be bonded together.
>
>> I was also told that the ground-rods we drove (3 ea 8 footers,
>> separated by at least 6 feet
>> and all tied together) must be the ONLY such ground system in the
>> entire home,
>
> WRONG
>
>> and that
>> every grounded item in the entire home must be connected to that and
>> only to that.
>>
>> So, why the apparent discrepancy?
>
> He is ignorant of the code. Not all that uncommon -- electricians
> sometimes get to be inspectors by longevity as electricians, or
> through "connections" within the industry.
>
>> For one thing, I suspect that the ~30' long ground wire from the
>> sub-panel to the main panel
>> is conducting RF, especially on 40 meters, into some of the
>> electrical appliances in the new
>> addition. I also believe that the present ground system in the shack
>> is not adequate, since at
>> present it is only being connected to the panel-ground through the
>> green grounding wires of
>> the electrical service.
>
> The earth is NOT a sump into which hum, buzz, and RF is poured. A
> connection to earth matters ONLY for lightning protection. Bonding
> (connecting all grounds together) is critical for lightning
> protection, electrical safety (shock, fires), and to some extent, hum,
> buzz, and RFI.
>
> I've written extensively on this, and the writing is not
> "pronouncements" but is accompanied by discussions of WHY.
>
> 73, Jim K9YC
>>
>> Ken W7EKB
>>
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