Rich,
I'm sorry that I'm going to have to disagree with you on this. You wrote
(in response to my warning that there
can be a voltage differential between neutral and ground):
> ** But only if the neutral wire is severed while the radio operator is
> standing in water without wearing his fishin' boots.
I appreciate the humor, but there have been sufficiently many tragic
occurrences of the 'electrical equivalent' of this
situation that there are now specific prohibitions in the NEC and local
electric codes.
As another poster pointed out, the neutral carries substantial current,
and a defective connection with can and will
cause a differential. As you point out, the peaks current can be much larger
than the average, and with startups of
electrical motors (e.g. air conditioners) there is a peak current that could
generate a substantial differential across
a relatively small resistance. Some residential systems are old and poor
connections are not uncommon. Further, in the case of
fault on the utility side, (I've seen HV transmission lines fall and come in
contact with the 240 V residential feed), this
the fault current would be distributed between the path to ground in the
service entrance and the connections between
neutral and ground - with disastrous results. In the past, there used to be
a 'grounding strap' that would bond ground and neutral
on large household appliances (stoves, driers etc). These are now
prohibited.
I understand your point that this is an unlikely occurrence, but it can
and does happen, and it is specifically disallowed in the
electrical codes. Since there was apparently some confusion in the initial
posting regarding the practice of attaching
neutral and ground, I wanted to underscore the importance of this.
But fishing boots are good too. ;-)
Ed
----- Original Message -----
From: "R. Measures" <r@somis.org>
To: "Ed Briggs" <edbriggs@optonline.net>; "Jason Buchanan"
<jsb@digistar.com>; "AMPS" <amps@contesting.com>
Sent: Wednesday, December 03, 2003 9:25 AM
Subject: Re: [Amps] 220V service for amplifier
>
>
> >Use a NEMA 6-20R and corresponding plug. For 20 amps, you need #12
> >conductors or larger. I use 3 #10 conductors with a 20 amp circuit
breaker
> >on my Centurion.
>
> ** For powering a single-phase amplifier with a capacitor-type HV
> filter, it is better to go with larger gauge wire than the electrical
> code specifies because I-peak is typically 10x I-average for capacitor
> filters. As a rule of thumb, for longish runs to big-uns, I use the
> largest gauge Cu wire that will fit in the receptical terminals.
> However, for resonant-choke filter supplies, the opposite effect takes
> place - but on a smaller scale, which is why Henry Radio's old 2k and 3k
> line of amplifiers are ideal for operation from a 120v outlet.
> >
> >The three conductors to the Centurion and to your (receptical) are two
hot
> >conductors and ground (not Neutral). The centurion does not use the
neutral
> >to develop 120 volts for the fan on a 240 v connection.
> >If you tie it to the neutral, there is a possibility of a voltage
> >differentail between the amp chassis and the earth ground which can
create a
> >dangerous situation.
> >
> ** But only if the neutral wire is severed while the radio operator is
> standing in water without wearing his fishin' boots.
>
> >You should not tie the ground and neutral together anywhere except at the
> >service entrance. For additional information see the National Electrical
> >Code and various study guides at a local public library.
> >
> >Here is a link where you can see various recepticals, including the NEMA
> >6-20R.
> >
> >http://www.evenheat-kiln.com/technical/recept/recept.htm
> >
> >Cheers.
> >----- Original Message -----
> >From: "Jason Buchanan" <jsb@digistar.com>
> >To: <amps@contesting.com>
> >Sent: Monday, December 01, 2003 10:19 PM
> >Subject: [Amps] 220V service for amplifier
> >
> >
> >>
> >> I did some searching through the list but haven't managed to hit the
> >> nail right on the head yet...
> >>
> >> For wiring a Ten-Tec Centurion amp to 220V, are there any recommended
> >> plugs and outlets to use?
> >>
> >> I am thinking about using a 3 or 4 prong clothes dryer outlet and plug
> >> combination for quick/easy disconnect, however the thing i'm wondering
> >> about is where the neutral and ground tie together, since i'm fairly
> >> sure that the Centurion doesn't have a 4 wire power cable running out
of
> >> it. Maybe i'm wrong (probably am wrong).
> >>
> >>
> >> Any help and advice how to properly wire the amp would be greatly
> >> appreciated.
> >>
> >>
> >>
> >> thanks,
> >> Jason
> >>
> >> _______________________________________________
> >> Amps mailing list
> >> Amps@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/amps
> >
> >_______________________________________________
> >Amps mailing list
> >Amps@contesting.com
> >http://lists.contesting.com/mailman/listinfo/amps
> >
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|