[BC] LAN Weirdness

[Tom Taggart]

The station is in a house, which I suspect was a DIY (Do It yourself)  
project for the original and sole owner back in '85.  So there is a  
fair amount of weirdness in the electrical wiring, such as not  
connecting the third wire (safety) ground at various outlets.

The switch, however, is mounted in a metal rack. The rack is tied to a  
2" copper strap, which in turn runs to several ground rods outside the  
building.  Neutral and safety ground for the rack power is tied to the  
strap. The electrical neutral and safety grounds for the house are  
tied to the ground strap by a 15 foot piece of #4 (since we couldn't  
find an easy way to run the strap to the box). There is strap run into  
the control room, which is connected to the console, and to the  
neutral and safety ground of the branch circuit for the control room  
equipment. This includes the 4 computers in the control room. The PD's  
computer, in his office, and my computer (in the rack room) aren't  
tied to anything in particular, except through the neutral. I know  
there is no safety ground on the outlet for my computer--but that  
computer was installed after the first time we had a lock-up of the  
switch.

The little router and cable modem (two separate units) sit right above  
the switch. They are in plastic cases, run by wall warts, but are all  
plugged into the same UPS. The cable modem, of course, is grounded to  
the copper strap by a feed-through "F" connector ground.  (Had a  
switch burned up at another location when I relied on the cable  
company's "ground" at the service entry box).

The computers on the LAN are connected by CAT5;(solid wire CAT5  
between rooms to jacks, jumpers to the computer, Leviton rack mount  
jack field in the rack, then jumpers into the switch). I presume there  
would be some way that a ground loop could develop depending on the  
design or failure of the NIC's in each computer, but one would assume  
the switch would account for this in the design.

RF: There's an Armstrong STL in the same rack--which drives my little  
weather radio nuts, but I would doubt that would cause this  
problem--or it would be a more continuous problem. Not one that would  
pop up when there is no-one moving around to reflect RF.