[AMRadio] 220 vac line

[Gary Schafer]

Well, a typical lightning bolt is on the order of 10 to 20Ka. 
The power company and the NEC are not real concerned with lightning
protection for your home. If they were they would require a much more
substantial ground system than they do. But the ground rods tied to the
panel are part of what they consider lightning protection.

73
Gary  K4FMX

> -----Original Message-----
> From: Bernie Doran [mailto:qedconsultants at embarqmail.com]
> Sent: Wednesday, July 27, 2011 2:37 PM
> To: garyschafer at comcast.net; Discussion of AM Radio in the Amateur
> Service
> Subject: Re: [AMRadio] 220 vac line
> 
> I beg to differ on earth ground being there for lightining, A typical
> bolt
> is 50,000 Amperes,.  a typical earth ground is 10 Ohms or more, NEC says
> 20
> Ohms is OK.   even with 10 a Ohm ground that is 500 KV above ground, how
> many feet away from your   "grounded"  equipment do you want to stand?
> ----- Original Message -----
> From: "Gary Schafer" <garyschafer at comcast.net>
> To: "'Discussion of AM Radio in the Amateur Service'"
> <amradio at mailman.qth.net>
> Sent: Wednesday, July 27, 2011 11:16 AM
> Subject: Re: [AMRadio] 220 vac line
> 
> 
> > Neutral must be grounded to earth at some place in your power
> > distribution,
> > usually at the service entrance panel.
> >
> > The SAFETY ground wire (bare or green) must also be bonded to the
> neutral
> > somewhere in the system, usually at the service entrance panel.
> >
> > If the hot wire should touch/short to the chassis the safety ground
> wire
> > becomes the return path for the current back to the neutral at the
> service
> > panel to ensure that the breaker will trip.
> >
> > The EARTH ground rod(s) are bonded to the neutral and safety ground
> wire.
> > Earth ground is not there to trip the breaker in case of a fault.
> Earth
> > ground is there for a lightning path and to prevent stray currents on
> > equipment.
> >
> > 73
> > Gary  K4FMX
> >
> >
> >>  Regarding the neutral, remember that is the wire that runs to the
> >> centertap
> >> on the 240 volt secondary service, that must be a solid connection to
> >> maintain the 120 each side of the line. The ground may or may not be
> >> connected to the neutral and is almost never a good ( low impedance)
> >> ground.
> >> The typical 8 ft ground rod is simply terrible, frequently 20 Ohms or
> >> so. If
> >> 120 goes to the
> >> "grounded" chassis it simply flows 6 Ampers or so to ground and the
> >> chassis
> >> would be at 120 volts.
> >>  My ground circuit here is eight 8 ft rods under and spread around
> the
> >> footer all bussed together with #4 Cu, another #4 goes to the big
> ground
> >> rod, 5 inch pipe 180 feet deep.  measures about one Ohm. The main
> panel
> >> has
> >> a big fat MOV block on the secondary side of a 60 Ampere breaker.
> >
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