[Amps] 220V wiring: Was Question about safety ground connection

[R.Measures]

On Nov 16, 2005, at 7:26 AM, Bill Turner wrote:

> At 05:20 PM 11/15/2005, Gudguyham at 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.

However, if a neutral is in place, and it is bonded to the cabinet, in 
the rare event that the safety-ground is severed, the cabinet could not 
possibly become a shock hazard.

> 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?

Since many ovens and dryers use 120v lamps for internal illumination, 
going to a 240v-components-only no-neutral circuit would be 
problematic.
>
> 73, Bill W6WRT
>
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>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org