Re: Conduits in a trench

["Robert L Bass" <RobertLBass@xxxxxxxxxxx>]

"RickH" wrote:
>
> Yes, a shield ground lift only works if the equipment being
> deprived of the shield ground also has a ground reference of its
> own via the power ground.  The incoming a/v signal is then
> referenced to that local ground instead of the interconnect ground
> which is undependable because it is floating at some level above 0
> volts, forming the hum loop.  He did say he was running a ground
> wire to the other building.

We're talking about two different concerns.  I was referring to
ground strike lightning rather than AC issues.  When multiple
structures are wired together and there's no bonded ground there is
an added danger of lightning entering through one structure's ground,
passing through your hardware and out through the other structure's
ground.  Even in a single structure this is enough of an issue that
the recommended procedure is to connect the grounds of all incoming
services to a single point or to a bonded ground system.  With
multiple buildings the danger can be worse than a single structure
due to the increased potential between points.

I assume you already know all this but I point it out for the benefit
of others who might not.  I don't disagree with what you've said
above.

--

Regards,
Robert L Bass

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