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breaker for kiln

updated wed 24 feb 10

 

Steven Walker on sat 20 feb 10


Hey,

I just picked up used kiln today. It's a Cress B-18-H in really good
shape that is a 23 amp, 240 volt and a Nema 6-30 plug. Trying to
determine what size breaker to use. Documentation on Cress website
doesn't tell what size breaker to use. I've got 50amp circuit in my
garage that I used to use for a welding machine before I built a shop
out back. Now that circuit in the garage is unused so I plan on using
it and swapping out the breaker and recepticle. I saw another kiln
manufacturer recommending a 40 amp breaker to use with their kiln with
a Nema 6-30 plug. Should I use a 30 amp or 40 amp breaker with this
Cress kiln?

Thanks fot the help!
Walker

Nancy Spinella on sun 21 feb 10


I went through the same thing with my own used kiln. :) After much research
I learned a few things:

1. A 23-amp/240v kiln needs a double-30 breaker and 10gauge copper wire
between the breaker box and the kiln.

1a. If your kiln were a 30-amp kiln, you would need a 40 amp breaker becaus=
e
your electrical load should only be 80% of the breaker. Any appliance that
goes over 24 amps needs a 40 amp breaker (30 x 80% =3D 24)

1b. If your wiring is <10awg you'll still be fine as long as you change out
the breaker.

2. The plug's rating is often not indicative of exactly what breaker you
need. My L&L is a 23-amp kiln, as it is -- with two rings. It's plug,
however, is made to go up to 50 amps (in case I add that third ring, so I
don't have to change out the plug... I confirmed this info with L&L custome=
r
support).

Have fun!!

--Nancy, who's not an electrician but still does her own wiring/rewiring




On Sat, Feb 20, 2010 at 10:25 PM, Steven Walker wrote=
:

> Hey,
>
> I just picked up used kiln today. It's a Cress B-18-H in really good
> shape that is a 23 amp, 240 volt and a Nema 6-30 plug. Trying to
> determine what size breaker to use. Documentation on Cress website
> doesn't tell what size breaker to use. I've got 50amp circuit in my
> garage that I used to use for a welding machine before I built a shop
> out back. Now that circuit in the garage is unused so I plan on using
> it and swapping out the breaker and recepticle. I saw another kiln
> manufacturer recommending a 40 amp breaker to use with their kiln with
> a Nema 6-30 plug. Should I use a 30 amp or 40 amp breaker with this
> Cress kiln?
>
> Thanks fot the help!
> Walker
>

Maurice Weitman on sun 21 feb 10


Steven, a 30 amp breaker is appropriate for a 23 amp load.

Regards,
Maurice

At 21:25 -0600 on 2/20/10, Steven Walker wrote:
>I just picked up used kiln today. It's a Cress B-18-H in really good
>shape that is a 23 amp, 240 volt and a Nema 6-30 plug. Trying to
>determine what size breaker to use. Documentation on Cress website
>doesn't tell what size breaker to use. I've got 50amp circuit in my
>garage that I used to use for a welding machine before I built a shop
>out back. Now that circuit in the garage is unused so I plan on using
>it and swapping out the breaker and recepticle. I saw another kiln
>manufacturer recommending a 40 amp breaker to use with their kiln with
>a Nema 6-30 plug. Should I use a 30 amp or 40 amp breaker with this
>Cress kiln?

Steven Walker on sun 21 feb 10


Thanks for the responses. First I don=3D92t think the plug on my kiln is
a Nema 6-30. The Nema 6-30 has two flat blades and one half moon
blade. My plug has two flat blades and on round blade. Plug with
round blade doesn=3D92t appear to fit into a receptacle with half moon
hole. I=3D92ve emailed Cress to find out what Nema style receptacle I
need. Also asked them what breaker they recommend for my kiln as
well.

The existing wiring on my 60 amp circuit is suitable for the kiln. It
is 8 guage (may even be 6 guage) and is only about a 20 foot run. I
don=3D92t plan to use the 50 amp breaker because of the potential for fire
if there is a problem with the kiln and and the breaker doesn=3D92t trip
before a fire starts.

From the responses I got, I believe a 30 amp breaker is the way to go.
I will see what Cress recommends and I will let y=3D92all know what they
tell me as well.

Thanks again!
Walker

KATHI LESUEUR on sun 21 feb 10


On Feb 20, 2010, at 10:25 PM, Steven Walker wrote:

> Hey,
>
> I just picked up used kiln today. It's a Cress B-18-H in really good
> shape that is a 23 amp, 240 volt and a Nema 6-30 plug. Trying to
> determine what size breaker to use. Documentation on Cress website
> doesn't tell what size breaker to use. I've got 50amp circuit in my
> garage that I used to use for a welding machine before I built a shop
> out back. >>

That 50 amp breaker is fine just as it is. Leave it and just change
the receptacle to fit the plug on your kiln. You'll never go wrong
having more capacity than you need.

KATHI LESUEUR
http://www.lesueurclaywork.com

Adron Lilly on sun 21 feb 10


On Sun, 21 Feb 2010 12:09:15 -0500, you wrote:

I went through the same thing with my own used kiln. :) After much
research
I learned a few things:
I think the breaker is sized to protect the wiring -not the load.

Make SURE your wiring is able carry the breaker rated current and
without excessive voltage drop. Your kiln will not perform as well
(slow or never reach cone) if the wire gauge does not take into
account the load as well as the length of the run.


>1b. If your wiring is <10awg you'll still be fine as long as you change =
=3D
out
>the breaker.


>Have fun!!

>--Nancy, who's not an electrician but still does her own wiring/rewiring

Nancy Spinella on sun 21 feb 10


Right. I believe if the run is 50 feet or more (might be 60? I can't
recall), you should go down to 8awg.

The breaker should be sized for the load if your wiring is greater than wha=
t
you need. If you have a 50amp breaker, it's not going to trip unless the
load exceeds what it's designed to allow to pass through. If your wiring ca=
n
handle this, it's no big deal. If you've got a problem and your 23-amp kiln
is somehow drawing more than 30 amps, your 50 amp breaker won't trip and yo=
u
might have a fire on your hands (or rather, wherever your kiln is).

The likelihood of such a situation happening is so slim you probably could
get away with the 50 amp breaker and never notice a difference, but it's so
easy to swap out a breaker, and they're fairly inexpensive as electrical
parts go.

--Nancy

On Sun, Feb 21, 2010 at 1:46 PM, Adron Lilly wrote:

> On Sun, 21 Feb 2010 12:09:15 -0500, you wrote:
>
> I went through the same thing with my own used kiln. :) After much
> research
> I learned a few things:
> I think the breaker is sized to protect the wiring -not the load.
>
> Make SURE your wiring is able carry the breaker rated current and
> without excessive voltage drop. Your kiln will not perform as well
> (slow or never reach cone) if the wire gauge does not take into
> account the load as well as the length of the run.
>
>
> >1b. If your wiring is <10awg you'll still be fine as long as you change
> out
> >the breaker.
>
>
> >Have fun!!
>
> >--Nancy, who's not an electrician but still does her own wiring/rewiring
>

Adron Lilly on mon 22 feb 10


IIRC electrical plugs/jacks/contacts have a thin coating that retards
corrosion, you don't want to scrape it off and expose the coated
metal.

A hard rubber eraser like we used to stick on the end of our pencils
was the tool of choice for cleaning contacts in lieu of some
commercial product. I don't know if this applies to house wiring type
contacts or not -but I'd check before scraping and such...

On Mon, 22 Feb 2010 15:27:23 -0500, you wrote:

>I've read that repeated plugging/unplugging can wear down the springs =3D
inside
>the outlet and make the connection loose (ever have to jiggle a plug to =
=3D
make
>it work? that's why.) -- but scraping the plug periodically to keep =3D
deposits
>from building up sounds like a good idea. What do you recommend to =3D
scrape
>it -- steel wool? X-acto knife?
>
>
>On Mon, Feb 22, 2010 at 10:27 AM, David Woof =3D
wrote:
>
>>
>> If this is not your choice or possible: make it a regular habit to =3D
plug and
>> unplug the unit, inspect the plug prongs, and scrape clean to keep the
>> arcing deposits from building up.
>>
>>
>>

Larry Kruzan on mon 22 feb 10


The right setup would be a 40 amp breaker, 8 gage wire, wire run less than
30 feet. Using 10 ga is asking for trouble with a kiln.

Personally I would opt for 6gage wire - if you elect to get the next size u=
p
kiln in the future you will be ready to go, with just replacing the 50 amp
breaker.

Larry Kruzan
Lost Creek Pottery
www.lostcreekpottery.com

PS. I was once an electrician.


-----Original Message-----
From: Clayart [mailto:Clayart@LSV.CERAMICS.ORG] On Behalf Of Steven Walker
Sent: Saturday, February 20, 2010 9:25 PM
To: Clayart@LSV.CERAMICS.ORG
Subject: breaker for kiln

Hey,

I just picked up used kiln today. It's a Cress B-18-H in really good
shape that is a 23 amp, 240 volt and a Nema 6-30 plug. Trying to
determine what size breaker to use. Documentation on Cress website
doesn't tell what size breaker to use. I've got 50amp circuit in my
garage that I used to use for a welding machine before I built a shop
out back. Now that circuit in the garage is unused so I plan on using
it and swapping out the breaker and recepticle. I saw another kiln
manufacturer recommending a 40 amp breaker to use with their kiln with
a Nema 6-30 plug. Should I use a 30 amp or 40 amp breaker with this
Cress kiln?

Thanks fot the help!
Walker





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Nancy Spinella on mon 22 feb 10


There's a great chart at http://www.nooutage.com/nema_configurations.htm

And Cress should be able to give you answers as well. L&L was helpful to m=
=3D
e
when I called about my used kiln.


On Mon, Feb 22, 2010 at 12:27 AM, Steven Walker wrote=
=3D
:

> Thanks for the responses. First I don=3D92t think the plug on my kiln is
> a Nema 6-30. The Nema 6-30 has two flat blades and one half moon
> blade. My plug has two flat blades and on round blade. Plug with
> round blade doesn=3D92t appear to fit into a receptacle with half moon
> hole. I=3D92ve emailed Cress to find out what Nema style receptacle I
> need. Also asked them what breaker they recommend for my kiln as
> well.
>
> The existing wiring on my 60 amp circuit is suitable for the kiln. It
> is 8 guage (may even be 6 guage) and is only about a 20 foot run. I
> don=3D92t plan to use the 50 amp breaker because of the potential for fir=
e
> if there is a problem with the kiln and and the breaker doesn=3D92t trip
> before a fire starts.
>
> From the responses I got, I believe a 30 amp breaker is the way to go.
> I will see what Cress recommends and I will let y=3D92all know what they
> tell me as well.
>
> Thanks again!
> Walker
>

Steven Walker on mon 22 feb 10


Yeah, I've seen that chart. That is where I originally thought I had a
6-30 plug. But have since realized my has a round prong and not a half
moon prong. Not much of a difference but would appear that the round
prong on my plug will not go into the half moon prong hole of the 6-30
receptacle.

I heard back from Cress on the breaker. They recommended a 30 amp
breaker for this kiln.

Waiting to hear back from them on the proper receptacle for my plug.
Since the kiln is probably 20-25 years old, the plug might not be a
current Nema configuration. That being the case, I might find that it
is best to just swap out the old cord/plug for a newer styled Nema
6-30 cord/plug. I'll see what Cress recommends and let y'all know what
they say.

Thanks all,
Walker

David Woof on mon 22 feb 10


Hi=3D2C

=3D20

Just to keep this clear: the breaker is not a regulator that effects capa=
=3D
city. It is there to interrupt "shut down" the electric flow in the event =
=3D
of an overload condition that is overheating undersized wiring=3D2C or a s=
ho=3D
rting or dead short condition=3D2C as in something going wrong in the kiln =
ci=3D
rcuits and controls=3D2C or the wiring anywhere being physically compromise=
d.=3D
Got any puppys=3D2C mice or rats who like to chew stuff?

=3D20

It protects the whole system from "frying" and fires. How many of us do th=
=3D
is?=3D2C and how foolhardy: to simply flip the breaker switch to reactivate=
a=3D
fter it trips off. Folks it tripped off for a reason=3D2C to protect you=
=3D2C =3D
find the reason!!!

=3D20

THE PLUG: over the years many studios have burned to the ground because t=
=3D
he plug prongs developed an arcing condition and eventually caused enough e=
=3D
lectrical resistance at this juncture to melt the receptacle box=3D2C burst=
i=3D
nto flame and.......and....and.....

=3D20

Better=3D2C if the kiln is to be in a permanent location=3D2C to hard wire =
the =3D
feed line into the wall power supply box. (Get a qualified electrician) or=
=3D
your insurance coverage may be compromised.

=3D20

If this is not your choice or possible: make it a regular habit to plug and=
=3D
unplug the unit=3D2C inspect the plug prongs=3D2C and scrape clean to keep=
the=3D
arcing deposits from building up.

=3D20

David Woof

=3D20

________________________________________________________________________
3a. Re: breaker for kiln
Posted by: "KATHI LESUEUR" kathi@LESUEURCLAYWORK.COM=3D20
Date: Sun Feb 21=3D2C 2010 12:53 pm ((PST))
=3D20
On Feb 20=3D2C 2010=3D2C at 10:25 PM=3D2C Steven Walker wrote:
=3D20
> Hey=3D2C
>
> I just picked up used kiln today. It's a Cress B-18-H in really good
> shape that is a 23 amp=3D2C 240 volt and a Nema 6-30 plug. Trying to
> determine what size breaker to use. Documentation on Cress website
> doesn't tell what size breaker to use. I've got 50amp circuit in my
> garage that I used to use for a welding machine before I built a shop
> out back. >>
=3D20
That 50 amp breaker is fine just as it is. Leave it and just change
the receptacle to fit the plug on your kiln. You'll never go wrong
having more capacity than you need.
=3D20
KATHI LESUEUR

=3D20



=3D20
_________________________________________________________________
Hotmail: Trusted email with Microsoft=3D92s powerful SPAM protection.
http://clk.atdmt.com/GBL/go/201469226/direct/01/=3D

Arnold Howard on mon 22 feb 10


From: "David Woof"
THE PLUG: over the years many studios have burned to the
ground because the plug prongs developed an arcing condition
and eventually caused enough electrical resistance at this
juncture to melt the receptacle box, burst into flame
and.......and....and.....
-------------
The first sign that something is wrong is that the power
cord is too warm. This is why it is a good idea to feel the
kiln's cord from time to time.

Extension cords are especially hazardous. Fire marshals hate
them.

Sincerely,

Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com

Steven Walker on mon 22 feb 10


Well, I'm told by Cress that the plug on the Cress B-18-H is a Nema
6-30. Apparently what I was seeing as a half moon prong hole in the
Nema 6-30 receptacle is not actually a half moon. Although it is round
on the top and flat on the bottom (like you would imagine a half
moon), it's not actually a half moon and the round prong should fit
into it. So, I'm off to the hardware store to buy a 30 amp breaker
and a Nema 6-30 wall mount receptable.

Thanks for all the input,

Walker

Nancy Spinella on mon 22 feb 10


I've read that repeated plugging/unplugging can wear down the springs insid=
e
the outlet and make the connection loose (ever have to jiggle a plug to mak=
e
it work? that's why.) -- but scraping the plug periodically to keep deposit=
s
from building up sounds like a good idea. What do you recommend to scrape
it -- steel wool? X-acto knife?


On Mon, Feb 22, 2010 at 10:27 AM, David Woof wrote:

>
> If this is not your choice or possible: make it a regular habit to plug a=
nd
> unplug the unit, inspect the plug prongs, and scrape clean to keep the
> arcing deposits from building up.
>
>
>