>Mike,
>
>An excellent question and its one I wrestled with painfully when
>connecting my Alpha 77Dx to service in my new home....
>
>Most amateur amplifiers do not require a neutral when configured for
>240VAC service. The sole purpose of the neutral in these
>applications is to adequately carry 120 VAC current: In the case of the
>Alpha 77, 77Dx/Sx, 70A, and 70V it is only the blower that
>requires 120 VAC irrespective of the 120/240 tap configuration in the amp.
> That blower always needs to see 120 VAC and it is not
>transformer tap-dependant. I suspect your Henry is wired in a similar
>way. This requires four wires: LINE-NEUTRAL-GROUND-LINE
>service. Remember, current should only flow through a neutral...never a
>ground. The Alpha manual suggests that tying the neutral
>and ground together at the amp is allowable. Back in 1970, perhaps it
>was....but as you'll see, its a safety hazard.
>
** There could still be a safety hazard on the chassis of the amp if the
neutral and the ground wires were to break at the same time. Perhaps it
would be wise to go with a 5-wire circuit ? There would be two line
wires, the neutral wire, the ground wire plus the emergency-backup wire.
On second thought, since #6 Cu wire is so easily broken, maybe an
emergency-backup backup wire and a 6-wire plug/socket would be safer yet ?
>While its true that the US wiring standard calls for the neutral and
>ground to be tied together, this is ONLY allowed at one point:
>the service distribution panel. Neutral and ground should never come
>together anywhere else in the electrical network. Why? If a
>neutral fault occurs (e.g., opens up) at the equipment end, current now
>flows through the ground wire (because neutral and ground
>are tied together at the panel), causing your BNC connectors, SO-239, RCA
>connectors and any other grounded connector on the back of
>your amplifier to conduct current for the 120 VAC demand; and thus the
>amplifier case has now become hot. If the blower had the
>ability to adapt 240 VAC through changeable taps as is the case in most
>amps, this would not be a problem and the required service
>would be LINE-GROUND-LINE....and no neutral.
>
>My solution and in my opinion, the ONLY correct solution for these amps is
>to run four-wire service to the panel. I used a 30A
>4-wire Hubbell Twist-Lock connector and was purchased from Home Depot.
>Fortunately, this change required no mods to the Alpha amp.
>To my surprise, Alpha tied neutral and ground together at the Cinch-Jones
>power plug. I simply cut the jumper on the power cord
>plug.
>
>-Paul, W9AC
>
>----- Original Message -----
>From: "Michael Tope" <W4EF@dellroy.com>
>To: "AMPS" <amps@contesting.com>
>Sent: Wednesday, December 11, 2002 10:43 PM
>Subject: [Amps] Neutral vs Ground Connection for 220 VAC
>
>
>> Hi All,
>>
>> Our club just inherited a Henry 2K-D which I was planning to
>> wire for the 220VAC service that we have available in the
>> shack. My quandry is how to properly connect the 4 wire
>> 220VAC wiring on the Henry (2-hot, 1-neutral, and 1-ground)
>> to the 3 pole 220 outlets in the shack? While its clear to me
>> that tying the neutral and the safety ground connnections on
>> the Henry together will work functionally, I am wondering if
>> this would be kosher from a safety/code point of view. Is
>> the third wire in a 3 prong 220 outlet supposed to be a safety
>> ground or is it actually allowed to carry neutral current in the
>> case where both 110V and 220V are needed inside the box
>> (it looks like the pilot bulbs and blower in the Henry use one
>> "phase" of the 220V circuit to get 110VAC)?
>>
>> Thanks,
>>
>> Mike, W4EF..................
- Rich..., 805.386.3734, www.vcnet.com/measures.
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