> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Bill Turner
> Sent: Wednesday, November 16, 2005 9:27 AM
> To: amps@contesting.com
> Subject: Re: [Amps] 220V wiring: Was Question about safety ground
> connection
>
> At 05:20 PM 11/15/2005, Gudguyham@aol.com wrote:
>
> >Your safest bet is to run 4 conductor wire and outlets. All new ranges
> and
> >dryer circuits must be 4 wire. As far as I am concerned, all new
> amplifier
> >circuits should be too.
> >
> >Mike, W1NR
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> I'm not sure that is the "safest" approach, event though it is allowed by
> NEC.
>
> IMO, the safest system is to use two hots and a safety ground, and no
> neutral at all. This requires having NO 120 volt circuits in the
> equipment, something which may require a bit of redesign, but is
> quite doable. This eliminates the rare but real possibility of
> problems due to an open neutral. As one other poster has observed,
> open neutrals have been caused on more than one occasion by lightning
> strikes.
>
> I believe NEC's position on allowing four-wire circuits is an attempt
> to placate all parties involved rather than create a more safe but
> awkward to implement (no-neutral) standard. Am I wrong?
>
> 73, Bill W6WRT
You are trying to make it complicated when it is not.
Suppose your neutral does open with a four wire circuit, your 120 volt fan
just stops running.
Same thing happens to your 240 volt power supply if one side of the 240 line
opens. Your amp stops working.
The reason the NEC allows four wire circuits is to bring the part of the
code that previously allowed neutral and ground circuits to be run on the
same wire (electric stoves) up to same standard as the rest of the code.
That is, "no safety ground shall carry current".
This has been the standard for all but a few exceptions in the past, stoves
and dryers. The code has been updated to not allow those exceptions any
longer.
73
Gary K4FMX
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