[Amps] Alpha 87A Power Supply Question

[Aleksandar Petkovic]

Not only that. In Australia, it is prohibited for anyone, other than a 
licensed electrician to even unscrew a power point from the wall.  even 
changing a plug or cord on an appliance is also out of bounds.

The fines for non compliance are very substantial.

The odd thing is that anybody can go to their local hardware store and 
buy all the things necessary to wire up their own house.

Go figure.

73, Alek, VK6APK



On 6/05/2021 8:56 am, Adrian wrote:
> Although, I am a VK, , I am also an A class Electrician here, and here 
> is how
>
> The SAA wiring rules relates to this matter for best safety, inline;
>
>
> On 6/5/21 10:01 am, MU 4CX250B wrote:
>> Hi Jeff and Jim,
>> I happily defer to your greater knowledge of electrical codes, about
>> which I know very little. I also understand that amateur equipment
>> powered off 240VAC should have four conductor power cords and internal
>> circuitry that separates chassis ground from Neutral. In that
>> circumstance, AC imbalance currents then return safely through the
>> neutral wire, while no load current flows into the ground connection.
>> No question that is the ideal setup, to which we should all aspire.
>
> Only L2 and L2 with ground is required. Neutral is not required, in 
> what is a ,
>
> simple AC path provided across L1 and L2 with no current imbalance 
> issue toi concern us in this application.
>
> The neutral if present should be connected to a terminal in the amp  
> for connection to 120v devices, fan etc,
>
> also fed from L1 or L2. If more than one device share the load using 
> L1 for some and L2 for the other 120v
>
> devices to share load. If the HV primary fails on one of 2 primaries 
> (open circuit), it would be better that the
>
> whole amp shuts down, so I would not recommend neutral connection to 
> the center tap if accessible.
>
> If we were dealing with heater banks then yes the neutral would be 
> beneficial at the primary load centre tap.
>
>
> Three or 2 phase supplied heater banks use a neutral to allow maximum 
> possible heater banks to operate,
>
> if one bank open circuits> fails ,  in a star (3ph star or wye wired) 
> or centre tap (2ph) connection with neutral
>
> connected to the star point or center tap respectively.
>
> nmeutral should never be connected to ground anywhere else in the 
> system but at the switchboard 'MEN (main earth neutral)'
>
> connection strip where a neutal and earth terminal block are connected 
> to gether and a main eath stake connected to the earth
>
> terminal block.
>
>
> This keeps ground and neutral potential equal. The appliance (which is 
> the amp here), must have its metal body grounded,
>
> unless double insulated from the exterior touched surface. The groung 
> connection is purely there for the purpose of keeping
>
> the exterior metal potential minimum and taking the surge currect to 
> ground , blowing the supply fuse in the case of insulation breakdown
>
> or other short to earth. It is there to save lives. The chassis should 
> never carry AC supply current otherwise.
>
> Connecting a neutral to chassis compromises this safety in known fault 
> conditions where the neutral to ground connection removes the safety 
> for the
>
> appliance user exposing that person to potential above ground.
>
>
> It is a safety issue.
>
>
> Any old amp should be updated and rewired to match modern standards, 
> otherwise you are playing Russian roulette with peoples lives.
>
>
> vk4tux
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