Excellent explanation -- thanks!! I hope you don't mind me replying to the
reflector so we can
all absorb this. I remember hearing this from my brother, who as I mentioned
in an earlier post
is an electrician. This does make me think of another question: Since my amp
(and several others)
has only the 2 hots and a ground, does that now mean the ground is acting as
the "Neutral"? And
what are the ramifications of grounding it again via the station ground? BTW,
my shack is
literally right next to the breaker box and power entry, so my 240 outlet is ~3
feet from the
breaker. The power ground may actually be closer than the station ground I put
in...
Thanks again,
Joe,
N3JI
--- Gudguyham@aol.com wrote:
> Hi Joe, coming into your house from the electrical company is a 3 wire system
> ONLY. You have HOT-HOT- NUETRAL from them. They ground their transformer at
> the pole to an earth ground. You ground your electrical system at your MAIN
> DISCONNECT. (to an earth ground) Notice I said MAIN DISCONNECT not MAIN
> PANEL.
> In most cases, the main disconnect is in the main panel, but in some special
> cases, the main disconnect is NOT in the main panel. The NEC requires the
> electrical system to be EARTH GROUNDED at the MAIN DISCONNECT. There are
> only 3
> wires from the power company (on a single phase 240/120 system) to the main
> disconnect point. After the main disconnect point (in most cases the main
> panel) any further SUB PANEL and branch circuits are then 4 wire systems (for
> 240v). The ONLY place in a distribution system where the NUETRAL and the
> GROUND
> (bond) are tied together is at the main disconnect point, after that point
> the
> NUETRAL and GROUND (bond) MUST be seperated, hence separate wires. The NEC
> says that the ONLY time that a GROUND (bond) should carry current is during a
> fault situation, a fault situation would be when a metal compartment, chassis
> or
> the like becomes energized by a HOT conductor, when this happens, current
> flows on the bond back to the panel, and trips the circuit breaker. If you
> tie
> the nuetral and ground together at any point then any current flowing on the
> nuetral will be shared by the bonding system, in the case of BX it would be
> the
> armour or in Romex the bare wire. You DONT want this as a rule!! It was
> common practice in the old days with dryers and ranges to tie the ground and
> nuetral together, but in the 1993 NEC code book they changed that, and now
> all
> range and dryer plugs have 4 prongs instead of 3. The confusing thing is
> that
> when you read the code book, they refer to the NUETRAL as the "grounded
> conductor" and the earth ground (bond) as the 'gounding conductor". You wont
> really
> see the term NUETRAL used in the codebook. Whats the moral of this story? If
> you add ANY 240 line in your house be it, a sub panel or a branch circuit DO
> NOT
> tie Nuetral and bond together. THEONLY TIME A NUETRAL AND BOND COME TOGETHER
> IS IN THE MAIN DISCONNECT POINT, WHEREVER THAT MIGHT BE. 73 Lou W1QJ King
> Conversions (electrician)
>
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