A lot of the residential wiring back then lacked a dedicated grounding
conductor. It only had two wires, a "hot" and a neutral, unlike the wire
used today which has three wires including a dedicated grounding
conductor. The neutral was also used as an equipment safety ground. If
the neutral opened up somewhere in the circuit, such a bad splice
somewhere in the house, you no longer had a ground and ugly things
happened when shorts would develop between the 120V conductor and the
cabinet.
Ian - K8MM
Carl wrote:
> Several commercial amps of the 60's, 70's and maybe later, including Alpha,
> Henry and Johnson connect the 120V devices between a 240V leg and ground.
> Apparently is was considered safe and legal back then when lawyers and
> nervous nellies werent running the country.
>
> Im not saying it is recommended, just that it was once acceptable.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Jim Brown" <jim@audiosystemsgroup.com>
> To: <amps@contesting.com>
> Sent: Tuesday, November 03, 2009 10:49 AM
> Subject: Re: [Amps] TL922 Power Plugs
>
>
>
>> On Thu, 29 Oct 2009 18:17:21 -0400, Ian Hill - K8MM wrote:
>>
>>
>>> Houses are typically feed off of a center tapped secondary. 240V
>>> measured between phase conductors and 120V between either phase
>>> conductor and the center tap. There isn't any sort of dangerous short
>>> by having the neutral ( i.e. center tap) and the ground bonded together
>>> in the primary distribution panel in a house....its supposed to be
>>> connected that way.
>>>
>> Exactly right. One other VERY important point -- it is both ILLEGAL and
>> UNSAFE to connect neutral to ground at any other point. The proper
>> connection of a 240V load is to the two ends of the transformer only,
>> and with the ground wire connected for safety.
>>
>> There is some equipment that needs both 240V and 120V to operate. That
>> equipment gets its 240V from the two ends of the transformer, and MUST
>> get 120V between one side of the transformer and NEUTRAL, NOT GROUND.
>>
>> 73,
>>
>> Jim Brown K9YC
>>
>>
>>
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>
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