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

To: "Gary Schafer" <garyschafer@comcast.net>
Subject: Re: [Amps] 220V wiring: Was Question about safety ground connection
From: R.Measures <r@somis.org>
Date: Thu, 17 Nov 2005 04:22:01 -0800
List-post: <mailto:amps@contesting.com>
On Nov 16, 2005, at 9:15 PM, Gary Schafer wrote:

>
>
>> -----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.

Good point.  Letting those in the business decide the national code 
virtually assures that more business will result.  I would not be 
surprised that - in the next 50-yrs - it will be determined by the 
"experts" that 4-wire 240v outlets are really and truly not safe 
enough, so 5-wire 240v receptacles will become the new national 
standard, and we will have 3 wires carrying zero current in a 240v 
circuit instead of only 2.
>
> Suppose your neutral does open with a four wire circuit, your 120 volt 
> fan
> just stops running.

Putting a R in series with the fan to drop 120v and running it from 
240v would prevent this possibility.
>
> 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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>
>

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

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