Wayne Whitney wrote:

On 2006-12-15, w_tom wrote:


[Earthing wire] not inside any metallic conduit


Why would this be? Sometimes it might be necessary to use metallic
conduit to protect the earthing wire from physical damage.

When run in steel conduit, the wire through the steel acts as a choke
and can significantly raise the impedance of the earthing wire. As volt
notes, the NEC requires the conduit to be bonded to the earthing wire at
each end so the conduit acts as a conductor in parallel to the earthing
wire.


Same rules also apply to cable TV and AC mains earthing wire. All
earthing wires should remain separated until all meet at their common
earthing electrode.


Given that the main panel/disconnect will have a grounding bar where
the Grounding Electrode Conductor terminates, is it good practice to
run the cable TV and telephone earthing wires directly to this grounding
bar?

Connect them to the grounding electrode conductor close to where it
leaves the service.

--
bud--