[Amps] FW: Bridging 120v loads across HV primary windings

[Joe Subich, W4TV]

 > You are wrong.  He must ground the tap where he gets the "neutral"
 > and provide some type of fuse or circuit breaker protection on the
 > "hot".

Not on your life!  One never grounds the wiper of a variac (auto-
transformer).  Connecting a 120 volt load between the center tap
of a primary and one load line is EXACTLY like an autotransformer.

There is no requirement that a neutral be connected to the panel
as long as the (plate) transformer can handle the unbalanced
primary current.

73,

    ... Joe, W4TV

On 6/2/2010 12:19 PM, Ron McCurdy wrote:
> Jim,
>
> I've been engineering electrical systems since 1962.  You are wrong.  He
> must ground the tap where he gets the "neutral" and provide some type of
> fuse or circuit breaker protection on the "hot".  Otherwise, if he
> accidentally gets the hot grounded to something, there will be an arc until
> someone runs to shut off the power to the transformer...it won't trip til
> someone is fried.
>
> Wouldn't want that on my conscience!
>
> Ron,  KE5QDA
>
> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Jim Brown
> Sent: Tuesday, June 01, 2010 1:36 PM
> To: AMPS List
> Subject: Re: [Amps] Bridging 120v loads across HV primary windings
>
> On Sun, 30 May 2010 14:34:35 -0400, Martin Flynn wrote:
>
>> Vic,
>> Run the 4 wire circuit and call it a day.    I ran this very issue by a
>> licensed master electrician on Friday.
>
>> Direct quote: "If any portion of the load is 120 volt, you need a
>> neutral.  If you are hell-bent on a 2 wire + ground supply, get a 208
>> volt fan and appropriately tapped transformer"
>
> Your licensed master electrican was WRONG. It is entirely legal, and
> entirely proper from an engineering point of view to place a 120V load
> across half of a center tapped transformer as long as that load is center
> tap is not grounded.
>
> 73,
>
> Jim Brown K9YC
>
>
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