Arnold Howard on wed 25 jun 03
The 4-wire system was required in the earlier Paragon A-series kilns
because they used 4-way rotary switches. Around 1987, we converted to
infinite control switches. That type requires a 3-wire system.
The 4-way rotary switch that we used had 2 elements wired to each
switch. On LOW, both elements fired on 120 volts. On MEDIUM, only 1
element fired on 120 volts. On HIGH, both elements fired on 240 volts.
Since the kiln was actually 120/240 volt, it required the neutral
current-carrying wire. The 4th grounding wire was for safety.
Technically, our 4-wire kiln will operate on 3 wires. That is why
Francis Darby and the others working here at the time fought
electricians so often. It will operate, but it's not considered safe.
Our UL Listing requires a 4-wire circuit.
Carl, from what I can tell, your understanding of electricity is
accurate.
Electric kilns that use infinite switches need only 2 current-carrying
wires. The third is a grounding wire.
I hope this helps those who have older 4-wire kilns.
Sincerely,
Arnold Howard
Paragon Industries, L.P.
www.paragonweb.com
From: Carl Finch
> >I'm glad to see the recent discussion of the neutral and grounding
> >wires. It has been the topic of debate for years even among
> >electricians.
>
> Arnold, I'm afraid I don't get it--what is the debate? Is it not true
that
> grounds (green or bare) are for safety, and that neutrals (white) are
for
> carrying current? And that for 240 volt power no neutral is needed?
But
> for 120 volts it is?
>
> If I'm wrong on any of this I'd really appreciate being set straight.
I
> don't want to end up knocked backwards off my chair onto the floor (or
> worse) when futzing with my kiln, as happened to one Clayarter, a few
weeks
> ago!
>
> >Paragon's earlier A-series kilns, which were last made in 1987, used
a
> >4-wire system. Paragon's CEO at the time, Frances Darby, often argued
> >with electricians who called for information about circuit
installation.
> >The argument was usually about the neutral and grounding wires.
>
> What was that argument about?
>
> >If you install a used Paragon A-series kiln with 4-wire plug, please
be
> >sure to use a 4-wire circuit.
>
> What was the purpose of the 4-wire circuit? That is, what was the 4th
wire
> (neutral) supposed to provide for the kiln?
>
> >A common practice is to connect the
> >neutral and grounding wires inside the wall outlet so that the kiln
can
> >fire on a 3-wire circuit.
>
> If people connected the neutral to ground and the kiln fired OK, then
it
> seems to me that the 4th wire was superfluous!
>
> >This isn't a safe practice.
>
> Why? [Although, of course, an electrical inspector would frown at a
> 4-conductor receptacle connected to a 3-wire circuit!]
>
> --Carl
> in Medford, Oregon
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