I'm obviously no expert in the American electrical code
(other than some of the stunts I see posted would be definite
no-go tricks over here). On the other hand, 230 volts is all
we have, we do get the odd American device that needs to be
modified for 230 volts, so..
>> That's correct and not just for appliances. Here's one real world potential
> > problem: If a 120V blower is used in a 240 VAC amp (e.g., older Alpha &
> > Henry), and one lead of the blower is connected to chassis as the neutral +
> > ground connection -- and if the neutral opens, current for the blower will
> > find its way to the load center through your grounded RCA, SO-239, BNC, or
> > any other chassis-grounded connector.
Typically, a transformer has a centre tap (so both windings can be
put in parallel for 110 volt service). I would connect the blower
between one of the leads and the centre tap. Voila -
the magnetic coupling of both windings (on the same code),
will make sure that the blower will get the right (half)
voltage.
The amps you talk about would be connected with 3-wire service
(L, N, G) over here. Plugs are symetrical, so you don't know
if L and N is reverted. Running single-pole power switches is
still OK: the only way to service these units safely is by
*pulling the plug* instead of flipping the switch (a double-pole
switch doesn't matter - would you depend your life on
both contacts working, always?). I made a habit of standing on
the power plug when working on these.
Keeping N and G separate is neccessary, as for one, N and L
may be reversed (remember, symetrical plug, see above),
secondly, 30 mA through the ground line (i.e. 30 mA difference
between L and N) will trip the GPF switch - end of story.
Which also means that if there's any way that 30mA of current
is leaking towards the ground cable, things *will* be switched off.
I feel very safe about this.
The Dutch use a slightly-modified version of the German Electrical Code.
We know the Germans about their thoroughness, and believe me,
they've done a good job on this.
73,
Geert Jan PE1HZG
(now, that 3+ kV anode voltage on these amps, well...)
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