The story I heard concerning the 3-wire vs. 4-wire 240 VAC wiring is that back
in the 1960s when we had the copper shortage, the NEC caved in and permitted,
for special cases, the neutral wire to be used as the grounding conductor (or
vice versa) - this obviously saved a bunch of wire. The exceptions included
that this could only be used when the circuit was connected to a single
appliance. Since then the industry (and NEC) is trying to get back to a full
4-wire 240 VAC setup and hence many of today's appliances come with
instructions
on how to go either way.
So it is acceptable to wire up a SINGLE 240 VAC appliance on a circuit with a
3-wire connection (i.e. with a single conductor which serves as both a
grounding
conductor and a neutral conductor). However it is preferred (although I don't
know if NEC states that preference) to use a full 4-wire system.
Bob Groh, WA2CKY
________________________________
From: Pete Smith N4ZR <n4zr@contesting.com>
To: amps@contesting.com
Sent: Tue, February 14, 2012 4:11:56 PM
Subject: Re: [Amps] Fw: Source for plate xfrmer
I just installed a new GE Monogram range. It came with a 4-prong plug
and cord, but with instructions for re-wiring to use a 3-wire circuit,
which I did. In involved jumpering the chassis of the stove to the
neutral wire. I have a hard time imagining that these instructions
would have been given if they were not compatible with the NEC or UL.
73, Pete N4ZR
The World Contest Station Database, updated daily at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at
reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000 and
arcluster.reversebeacon.net, port 7000
On 2/14/2012 1:04 PM, Carl wrote:
>
>> There are no 4 prong outlets in my house so I guess I am doomed and also
>> damned as Im not going to rewire anything but the new appliance when and
>> if I need it.
>>
>> Carl
>> KM1H
>>
>>
>> ----- Original Message -----
>> From: "Al Kozakiewicz"<akozak@hourglass.com>
>> To:<TexasRF@aol.com>;<km1h@jeremy.mv.com>;<ranchorobbo@gmail.com>;
>> <steve@dx4win.com>
>> Cc:<amps@contesting.com>
>> Sent: Tuesday, February 14, 2012 11:08 AM
>> Subject: RE: [Amps] Source for plate xfrmer
>>
>>
>> First off, NEC codes end at the outlet. An amp is an "appliance" and
>> would be covered by UL, which is entirely optional. There is nothing that
>> forbids such a practice - an electric range is a good example as the overn
>> elements are typically 240v, while the burners, controls and lamps are
>> 120v.
>>
>> The issue is that a range uses a 4 prong outlet - 2 x hot, neutral and
>> ground, while your typical amp/AC outlet is missing the neutral. You may
>> NOT connect your fan between a hot and the chassis ground, even though it
>> would be electrically rational. If the safety ground failed, the chassis
>> would then be at 120v with respect to ground.
>>
>> Al
>> AB2ZY
>>
>> ________________________________________
>> From: amps-bounces@contesting.com [amps-bounces@contesting.com] On Behalf
>> Of TexasRF@aol.com [TexasRF@aol.com]
>> Sent: Tuesday, February 14, 2012 10:54 AM
>> To: km1h@jeremy.mv.com; ranchorobbo@gmail.com; steve@dx4win.com
>> Cc: amps@contesting.com
>> Subject: Re: [Amps] Source for plate xfrmer
>>
>> I guess there is some electrical code that forbids connecting the 120vac
>> blower between one side of the 240ac line and neutral?
>>
>> I hope this doesn't start another round of ground vs neutral wiring sins.
>>
>> 73,
>> Gerald K5GW
>>
>>
>>
>>
>>
>>
>>
>> In a message dated 2/14/2012 9:41:22 A.M. Central Standard Time,
>> km1h@jeremy.mv.com writes:
>>
>> You can get more benefit with primary taps and not bothering with a pair
>> of
>> 120V windings; use a seperate 120V line for blowers, LV supplies, etc.
>>
>> Tapping the secondary limits your KVA as you go to lower voltages and who
>> the heck needs a CT in a big amp?
>>
>> Carl
>> KM1H
>>
>>
>> ----- Original Message -----
>> From: "Rob Atkinson"<ranchorobbo@gmail.com>
>> To: "Steve Bookout"<steve@dx4win.com>
>> Cc:<amps@contesting.com>
>> Sent: Monday, February 13, 2012 10:10 PM
>> Subject: Re: [Amps] Source for plate xfrmer
>>
>>
>>> In addition EPD makes a good product but plan on spending at least
>>> $400, perhaps more.
>>>
>>> http://epd-inc.com/
>>>
>>> How much are you prepared to spend? Because of the price of copper
>>> any custom plate iron you get that has some muscle is going to
>>> probably cost some coin. More if you want it potted and several taps.
>>> Even if you don't need them if you are paying for a custom job it's a
>>> good idea to get a CT on the secondary and of course one on the
>>> primary, plus a few more taps on the secondary. You may decide 4.25
>>> KV DC with a cap input filter is a bit high, or if not, extra taps
>>> afford different supply voltages and increase the versatility of the
>>> transformer and its resale value if you ever decide to let it go.
>>>
>>> 73
>>>
>>> Rob
>>> K5UJ
>>>
>>> On Mon, Feb 13, 2012 at 12:35 PM, Steve Bookout<steve@dx4win.com>
>> wrote:
>>>> Hello all,
>>>>
>>>> Where do you look for a new HV plate transformer these days?
>>>>
>>>> I understand Peter Dahl is no longer around.
>>>>
>>>> I'm looking for 3000 VAC secondary @ 1+ amp CCS.
>>>>
>>>> TIA
>>>>
>>>> 73 de Steve, NR4M
>>> _______________________________________________
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>>> Amps@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
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