[TowerTalk] Grounding

N. S. FIRESTONE w3svj@juno.com
Thu, 5 Nov 1998 19:29:02 -0500

One of the really dangerous/destructive situations that can occur when
the ground and neutral never make it to our panel board is that 220 could
appear across some electrical device. The line voltage coming to the
house is usually furnished by the secondary of a 240 volt center tapped
transformer. That center tap is connected to the utility company ground
at the transformer pole and is supposed to be grounded at the customers
house through ground rods and water pipes etc. If all of these
grounds/neutrals come undone you effectively have no place for the load
to go to so it goes across the common panel neutral bus and back to some
other device on the other side of the line. That works ok if you have 2-
100 watt light bulbs on each side, effectively in series but what if you
have a 1.5 kw room heater looking at your very expensive xcvr power
supply. It may not push it to 240 volt but it's going to be right up
where it could smoke something. Can't do much about the utility side but
check the panel board electrical grounds and grounding conductors. New
installations require two eight foot ground rods with a number 6 cu
grounding conductor. Has very little to do with rf or lighting, it's line
voltage management that we are looking at.

73 de Nate, W3SVJ, in Pittsburgh where it's not so smokey anymore.

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