Technically, a ground wire covered by the deck is a violation of the
National Electrical Code. Likely the rod was there first, and the deck
was built over it.
Breaker boxes, switched disconnects, panel boards and ground rods must
be accessible for inspection and repair. It is common for ground rod
connections to get disturbed by ground shifting, hit by grounds keeping
equipment, etc. and thus require the clamp to be tightened over time.
The typical house or ham ground rod does little to improve your RF
performance, as the inductance of the long lead between the shack ground
bus and the electrical entry ground rod will often mean you have a
quarter wave situation at the high bands, ie high impedance at one end
where your rig connects.
Better to put a buried halo ground around the house outside the
foundation, and connect, (bond) both electrical grounds and the
communications grounds, as well as ham radio ground to it.
That way, you have provided a physically short path to earth from any
place in the house where the shack might be.
Be aware however, everything bonded together, with the case of a less
than good conducting earth, that you could have a hit on an antenna mast
or tower, bonded to the common bus. The whole of the bonded system will
rise to a very high potential, and might conduct harmful currents into
equipment bonded to everything else. We had this happen at the club
station: tower was hit, current came in on shields of coax, (coax was
INSIDE the tower), and continued into the shack where it went around the
room on our bus bar, up into a VHF radio, and vaporized the circuit
board negative power trace before arcing through the power supply to the
AC third pin ground path back to the AC utility ground.
The ground bus was L shaped around two sides of the room and on the
short side went out to a metal water supply piping system. Everything
was bonded to it with wide flat conductors, thus low inductance.
All AC outlets were bonded by the AC wiring (3 wire plus conduit).
Sometimes it is just going to get you if equipment is left plugged in.
Stuart Rohre
K5KVH
|