[Amps] Transformer question

Sun Jul 8 21:55:17 EDT 2007

Yes Gary, they revamp that code every few years...  Things like Arc Fault
breakers and crap like that.

-----Original Message-----
From: Gary Schafer [mailto:garyschafer at comcast.net] 
Sent: Sunday, July 08, 2007 8:47 PM
To: rbonner at qro.com; 'jeremy-ca'; 'Tom W8JI'; 'Amps Amps'
Subject: RE: [Amps] Transformer question

Before Carl goes out and looks at his stove or dryer and comes back and
tells you that they only have 3 prong plugs on them; 
The old NEC DID allow a few dedicated circuits like dryers and stoves to
have neutral and ground as a common lead to provide 240 and 120 volt
circuits. There are still many of those still in service and you can still
buy the 3 prong plugs and outlets just for that purpose.
However all new wiring for these appliances must now be 4 wires with
separate ground and neutral as Bob and Tom speak of.

73
Gary  K4FMX

> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Robert Bonner
> Sent: Sunday, July 08, 2007 8:28 PM
> To: 'jeremy-ca'; 'Tom W8JI'; 'Amps Amps'
> Subject: Re: [Amps] Transformer question
> 
> Oh my goodness here we go again discussing how to put a plug on a ham
> amplifier.
> 
> After having worked in the past as a professional electrician not a ham
> wiring his own rig I have found:
> 
> 240V circuits don't have neutrals...  They have each side of the line plus
> a
> safety ground.  A pair of blacks, a red and a black, or a pair of reds.
> The
> safety ground is either bare or it is GREEN.
> 
> A 240/120 circuit to power SOME ranges, maybe dryers, ovens whatever have
> both 240V components and 120V components.....  Something like a 120V
> outlet
> on the backsplash on a 240V appliance.  This is a 4 wire installation.  A
> pair of lines, a white neutral (with a neutral buss) and a green safety
> ground.
> 
> At no point in the existence of the world is NEUTRAL = GROUND.  However
> the
> two are connected together at your main service entrance panel...  PERIOD.
> They are not connect together at any subfeed panels.
> 
> The two are connected together BECAUSE...  Your power company provides two
> lines and a neutral to power your house.  YOU provide the ground.  This is
> done at the panel with the two tied together.
> 
> NOW, if you want to build a ham rig with 240/120 power, go right ahead.
> If
> you WANT TO DO IT TO CODE, you better hang a 4 wire cord on the damn thing
> and a 4 conductor plug.  You better not GROUND that neutral putting the
> 120V
> return currents on the chassis.  It requires an additional NEUTRAL BUSS...
> Do it!
> 
> There isn't a ham rig in the world that to code runs 240/120 circuits.
> 
> HOWEVER...  The Alpha 77DX/SX illegally ran a two wire cord plus ground
> and
> utilized the chassis as a neutral. This rig should have been a 240/120
> system.  I'm surprised it went to production.  It obviously wasn't UL
> approved.  Or somebody wasn't looking close if it was.
> 
> Just because you can do it doesn't make it right.
> 
> TOM, does know what he is talking about.
> While I don't bow to him in the east every morning, I haven't found him to
> be wrong on many occasions.
> 
> If I do I will make sure I let him know and I'm sure he would expect me to
> do so.
> 
> BOB DD
> 
> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of jeremy-ca
> Sent: Sunday, July 08, 2007 6:51 PM
> To: Tom W8JI; Amps Amps
> Subject: Re: [Amps] Transformer question
> 
> So then you are trying to convince us that anyone who has a 240V dryer,
> range, AC, Air Compressor or similar device with the neutral tied to the
> ground at the wall outlet and at the device has a safety issue.
> Sorry Tom, but the NEC manual disagrees with you and Id much rather follow
> what the experts say.
> 
> And I have yet to see any 240V single phase ham amplifier manufacturer
> provide a 4 wire cable.
> 
> In looking thru my amp manuals going back 40+ years I see that all 240V
> configurations show the neutral connected to chassis ground. This,
> strangely
> 
> enough, includes Ameritron and verified with the AL-1200 on the bench for
> repairs.
> 
> As you state Tom, this really isn't complicated.
> 
> Carl
> KM1H
> 
> 
> 
> ----- Original Message -----
> From: "Tom W8JI" <w8ji at w8ji.com>
> To: "Amps Amps" <amps at contesting.com>
> Sent: Sunday, July 08, 2007 3:36 PM
> Subject: Re: [Amps] Transformer question
> 
> 
> > >
> >> When I completely wired my current home I followed the NEC
> >> code and had no problem with any level of inspection
> >> including many 240V outlets in the shop, shack, and
> >> garage.
> >
> > This really isn't complicated.
> >
> > If you have the neutral connected to the safety ground or to
> > the chassis of any device at any point other than the main
> > panel, you have faulty wiring.
> >
> > If there is any connection from the chassis or other exposed
> > conductive parts to the power line neutral, you have faulty
> > wiring.
> >
> > Any return currents for 120 have to be through the neutral,
> > and the ONLY point the neutral can be connected to the
> > safety ground is at the main breaker box.
> >
> > So if we build an amplifier and tie one end of a 120V
> > transformer to the chassis, it is a safety issue. It doesn't
> > pass code and also presents a hazard to the user.
> >
> > This means if you have a PA that uses a neutral return to
> > obtain 120V it has to use a four wire outlet. You just
> > shouldn't wire it to a three wire plug. We should never
> > ground one primary end of a blower or filament transformer
> > to the chassis. The reason being if the neutral opens the
> > cabinet would have 120V on it.
> >
> > It has been this way by regulation at least 30 years now,
> > and it was good common sense long before then. So unless he
> > has a double insulated cabinet or a four wire outlet, he
> > cannot simply ground the filament or control primary to the
> > chassis or the safety ground of the power system.
> >
> > 73 Tom
> >
> >
> >
> >
> >
> >
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> 
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