[Elecraft] (OT) Grounding Mat

[Jim Brown]

On Sat, 27 Mar 2010 09:32:12 -0400, Don Wilhelm wrote:

>An isolation transformer *does* isolate the neutral (and the hot), 

NO! This is a summary of NEC (National Electric Code) requirements: The 
NEUTRAL of a transformer on the secondary side MUST be bonded to the 
equipment ground (steel conduit, the green wire, building structure, etc), 
and that green wire must be carried from the breaker panel to each outlet and 
to the transformer.  The neutral conductor that feeds the primary side of the 
transformer must be bonded to ground at the service for the building (that 
is, the main breaker panel). And, as we all know, all groundes must be bonded 
together. Thus, an isolation transformer does NOT isolate either the neutral 
or the equipment ground. 

What an isolation transformer DOES do is reduce the voltage between neutral 
and ground to zero. It also shortens the return path for leakage currents on 
the green wire -- they now return to that transformer, not to the more 
distant breaker panel at the service entrance. This has the potential to 
reduce noise current on the shield of signal cables. BUT -- the simple 
bonding regimen outlined in my Ham Interfacing Power Point is a MUCH less 
expensive AND more effective solution. 

73,

Jim Brown K9YC