That's certainly true for the 87A being discussed here and most modern amps.
However, some older amps like my Alpha 70 and 77 series have the blower
connected between L1 and the chassis where in those designs the chassis
functions as both neutral and ground because of the blower wiring error.
The fix is actually very easy when 4-wire service is available. Not so easy
when it's not. Manufacturers did things like that back then. Although not
strictly a NEC violation, that practice violates many local codes and
product wiring standards since the wiring fault is inside the product and
not the premise.
In the Alpha 70/77, the blower is in series with the HV primary by design
which causes the blower to increase its speed when the amp is under full
load. If a 120VAC blower must be used and a neutral isn't available,
probably a better approach (like the Alpha 86) is to insert the blower
between L1 and a 240VAC primary transformer CT if it has one.
Paul, W9AC
-----Original Message-----
From: Amps <amps-bounces@contesting.com> On Behalf Of Jim Brown
Sent: Tuesday, May 4, 2021 4:08 PM
To: amps@contesting.com
Subject: Re: [Amps] Alpha 87A Power Supply Question
On 5/4/2021 7:24 AM, MU 4CX250B wrote:
> I believe the appropriate hookup depends on the circuitry. As already
> noted, the guiding principle is that return current should always be
> through neutral, and never through ground.
NO, NO, NO!
As K4FMX has correctly told you, the amp needs ONLY Line, Line, and Ground.
It does NOT need Neutral, and you should make no connection to it. It is a
HUGE violation of Code to connect Neutral to Ground anywhere except the
Panel where power enters your home.
73, Jim K9YC
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