[AMRadio] 220 vac line

[Bernie Doran]

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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