RE: grounding question

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>

Big green ground in place! Trip those breakers for life.

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Saturday, October 14, 2006 8:43 AM
To: tesla@xxxxxxxxxx
Subject: Re: grounding question

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Jim, Not sure which Jim

I think I figured out the issue after replying last nite.  The issue
is NOT GROUND.  The issue is NEUTRAL.  You can short the HOT to earth
ground and nothing happens other than some current flows (assuming no
GFI).  Only if you short the HOT to NEUTRAL will the breakers
pop.  If an instrument case is RF grounded and HOT becomes shorted to
case, there is no guarantee the breakers will pop because the earth
ground impedance is too high.  If the case is green wire grounded,
enough current will flow to trip the breaker hence line safety is
provided. If the breaker box is ungrounded (lets say because the
ground has dried out, the green wire is still connected to NEUTRAL at
the box which is a low impedance return for the line.  Safety is
provided by the green wire connection to NEUTRAL. The Whole point true with
appliance faults too in a fault condition, Yes! <snip>