>Since neutral is normally used to conduct return
>current, when used as neutral, there is guaranteed to
>be a difference of voltage between neutral and ground,
>in the shack. That's the rub, when you don't do
>things the NEC way.
* A potential rub would exist if I did not (simply because green is the
wrong color according to the NEC experts) make sure the chassis of the
SB-220 was connected back to the ground/neural terminal-strip in the
breaker box.
- Some may have driven to an electric-supply emporium, purchased a line
cord with 4-wires, rightly colored red-black-green-white, but I am not
one of them. The SB-220 chassis needed to find its way to the
ground/neutral terminal strip on the breaker box, and I saw to it.
Sure, if a HV primary winding dead-shorts on the 220, there will be c.
55Vrms between the chassis and ground for as long as it takes to open the
circuit breaker, but this hasn't happened in the last 27-years, and if it
did, the chances of it happening when the shack is flooded and I'm
operating without wearing my (nearby) fishin' boots are about as likely
as finding a snowball in Hell, or even finding one in Purgatory.
-- OK, I already know I am a weird guy because I carry scissors in my
motor vehicles for cutting the safety-belts that jam unsafely in 5% of
motor vehicle accidents.
>
>Rich, it sounds as if you are simply fortunate. You
>have a 240VAC outlet whose neutral is not shared with
>other circuits.
** The neutral in the 240V outlet for the amplifier is shared with every
120V and every 240V circuit in the house because All of the neutrals
connect to the neutral/ground terminal strip in the breaker-box. If I am
fortunate, it is that I know Ohm's law good enough to get by.
>Since the third wire goes back to the
>box, and at the box it is connected to both ground and
>neutral, then it is simply a matter of naming whether
>you call it "neutral" or "ground".
>
** even if it is the "wrong" color.
>If, in fact, you have it connected to chassis, and if,
>in fact, you are not using it for return current, then
>whatever name you have chosen to call it, you are
>functionally using it in the NEC definition of
>"ground".
** true, although it is the wrong color. Maybe I should pick up some
red, green, white and black fingernail polish at K-Mart? I know black
fingernail polish sounds weird, but I know it is available somewhere
because I see teenbabe freaks wearing the stuff, along with
color-coordinted black lipstick and purple spiked hair.
>
>If the Heathkit power cord has a green wire, and the
>"third" wire in your outlet is green,
** The third wire is bare #12 Cu.
> and you are not
>sending return current down it, then you have it wired
>as ground - not neutral.
>
>If you are sending return current down that wire, AND
>you have it connected to chassis, then you are using
>it simultaneously for ground and neutral.
>
__ Which is what I do on the 240v outlet for the tetrodes-with-handles
mains outlet. // The imbalance current is c. 85mA-avg in the
neutral/ground because I utilize one side of the mains-neutral potential
to power a half-wave rectified, C-filtered 160VDC supply for operating
the high-speed T/R relays. Although there are some who would be alarmed
about the potential-drop in 99' of #6 wire at 85mA, I am not one of them.
>Ohmmeter readings are interesting, but are not the
>defining item.
>
** Know ye not that Ohm's law is Sacred Gospel?
>The defining item is what kinds of currents do you use
>the wire to carry. If you use the wire to carry
>normal return currents, then your usage of the wire is
>as a "neutral". If you use the wire to carry fault
>currents, then you are using it as a "ground". If you
>are using it to carry both, then you are using it as
>both neutral and ground, which is possible within the
>realm of physics, but there are more fault conditions
>that will result in a hazard, than if you used it
>differently.
>
>So, being a bit repetitive - it is a neutral or ground
>only depending on your usage of the connection.
** Both, but within reason in my opinion because 85mA in 99' feet of #6
is no biggie. Sure, I could install a 50w isolation transformer, but
would it buy me anything signicficant?
- So if is it OK according to Code for a neutral wire to carry current
in a 120v outlet, why it is apparently a Code no-no for the neutral wire
in a 3-wire 240V outlet to carry current?
>The color (green for ground, white for neutral) is only
>the NEC's ruling on what color should represent what.
>A green wire is not ground - a wire that will carry
>fault current is ground. It might be green (thus
>meeting NEC code) or it might be white (thus violating
>NEC code) but it is still ground.
** During a lightning strike, green, black, red, black and white carry
fault current.
** If the county ever sends an official electrical inspector around, I
will tag along with the four bottles of fingernail polish.
cheers, Dave
>--- "R. Measures" <r@somis.org> wrote:
>>
>>
>> >I agree with Dave. I recently wired an SB-221 for
>> >240V service. It was wired exactly as Dave
>> >describes (third wire is chassis to AC
>> >mains safety ground connection). There is no
>> >connection between the amplifier and the AC
>> >mains neutral.
>>
>> ** If there is no connection between the two. what
>> is the potential
>> difference between the neutral and ground?
>
>And the answer is: It doesn't matter! If you're not
>using neutral, it can go whichever way it wants, and
>the operation and safety of the amp and op are not compromised.
>
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