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## kiln specifications - the watts and the hertz

### Fredrick Paget on tue 10 jul 07

>Hello All;
>
>I am learning to read and compare kiln specs. I have
>questions regarding Watt and Hertz.
>
>1- What are my concerns whether the numbers are high
>or low? Say two 30 Amp kilns; Kiln A is 5500 Watt and
>Kiln B is 7200 Watt. What is the difference from a
>user's point of view?
>
>2-Ditto with Hertz
>
>May
>Brooklyn NY

May,

This "does not compute" as they say.

Both Hertz and Watt were distinguished scientists that have had
electrical units named for them. Hertz used to be called "cycles per
second". In the United States the standard electricity is all 60
Hertz so you can not use that in comparing kilns here. (In England
they use 50 Hertz. But even so for resistive loads like kilns it
doesn't matter. So forget Hertz.

On the other hand you said that both kilns were 30 amps (Ampere -
another distinguished scientist of the past) and give two different
wattages.
There is a defining mathematical relation between amps ,watts and
voltage (Volta - another distinguished scientist).
It is W=EI ( watts = volts times amps). So it is easy to figure out
the voltage. (E=W/I)
I have no problem with 7200 watts at 30 amps as that is 240 volts
but 5500 watts at 30 amps gives 189 volts and that looks fishy to me.
189 is not a standard voltage so it does not compute. We have 120,
208 and 240 volts supplied.
If they are both 240 volt kilns then the current for the 5500 watt
kiln is 23 amps. It is probably a smaller kiln - either that or it
is much better insulated.

Fred Paget

--
Twin Dragon Studio
Mill Valley, CA, USA

### jim on tue 10 jul 07

The Amp listing is often the size breaker / circuit it must be on. The
wattage will determine just how many amps it will pull. The 5500 will pull
less amps than the 7200. In fact I don't know if I would have a 7200 on a
30 amp circuit as that is about max for that. On the other hand,
theoretically the 7200 watt should heat faster...

On Tue, 10 Jul 2007 20:14:31 +0100, May Luk wrote
> Hello All;
>
> I am learning to read and compare kiln specs. I have
> questions regarding Watt and Hertz.
>
> 1- What are my concerns whether the numbers are high
> or low? Say two 30 Amp kilns; Kiln A is 5500 Watt and
> Kiln B is 7200 Watt. What is the difference from a
> user's point of view?
>
> 2-Ditto with Hertz
>
> May
> Brooklyn NY
>
>
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_
> Send postings to clayart@lsv.ceramics.org
>
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>
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### May Luk on tue 10 jul 07

Hello All;

I am learning to read and compare kiln specs. I have
questions regarding Watt and Hertz.

1- What are my concerns whether the numbers are high
or low? Say two 30 Amp kilns; Kiln A is 5500 Watt and
Kiln B is 7200 Watt. What is the difference from a
user's point of view?

2-Ditto with Hertz

May
Brooklyn NY

### Arnold Howard on wed 11 jul 07

From: "May Luk"
> 1- What are my concerns whether the numbers are high
> or low? Say two 30 Amp kilns; Kiln A is 5500 Watt and
> Kiln B is 7200 Watt. What is the difference from a
> user's point of view?
>
> 2-Ditto with Hertz

amps x volts = watts

If you plugged a 30 amp kiln into a 240 volt circuit, you
would have 7200 watts of power. In a 208 volt circuit, power
for that kiln would drop to 6240 watts. The more watts per
cubic foot of kiln, the higher the temperature you can fire
to. For this reason it is important that you know the
voltage in your building before ordering a kiln.

Hertz is cycles per second of alternating current, which
varies by country. This is usually not an issue with kilns.

Sincerely,

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

### nanspin-AT-gmail on wed 11 jul 07

(Watts) = (Volts) x (Amps)

There are 240 volt and 208 volt kilns out there. If you're researching to
get one for yourself, find out what you have!

Good luck...
--Nancy

On 7/10/07, May Luk wrote:
>
> Hello All;
>
> I am learning to read and compare kiln specs. I have
> questions regarding Watt and Hertz.
>
> 1- What are my concerns whether the numbers are high
> or low? Say two 30 Amp kilns; Kiln A is 5500 Watt and
> Kiln B is 7200 Watt. What is the difference from a
> user's point of view?
>
> 2-Ditto with Hertz
>
> May
> Brooklyn NY
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
>

### Lynne and Bruce Girrell on wed 11 jul 07

>1- What are my concerns whether the numbers are high
>or low? Say two 30 Amp kilns; Kiln A is 5500 Watt and
>Kiln B is 7200 Watt. What is the difference from a
>user's point of view?

The primary thing that the watts determine is the maximum temperature
attainable by the kiln. Watts are a measure of power. More power = higher
attainable temperature. A higher power kiln would also be able to reach
temperature faster or could make a faster climb in the firing schedule.

The situation that you describe - two kilns requiring the same amperage, but
producing different power levels implies that the power source is a
different voltage. Watts = volts times amps. So if amps are constant and
watts increase, that means that the voltage must also increase. For example,
a kiln operating at 115 volts and pulling 30 amps will use 3450 watts (115 x
30 = 3450), but a kiln operating at 230 volts and pulling 30 amps will use
6900 watts. Except for very small kilns, you should expect to use 230 volts.

The downside of more power is that everything gets bigger and more
expensive. And, of course, you use more power in a firing. Finally, the
higher you go in temperature, the shorter the life of your elements.

Look through suppliers' catalogs and note the maximum cone that the kilns
are rated for. That's really what you're after. Then note the power
requirements. You'll find that all kilns firing to cone 6, for example, will
have similar power ratings (and if you find one that is significantly
different, start asking questions). A very well insulated kiln might require
less power and a poorly insulated one will require more power. There's
really no way to cheat the system.

>2-Ditto with Hertz

Resistive elements (the kiln heater elements) don't care a bit about Hertz,
but the controllers might. A well built power supply really shouldn't care
about the line frequency, but if the designers were cutting costs or simply
didn't think about the possibility of running on 50 Hz, then the electronics
might not function properly. In the US you have 60 Hz power. No other
choice.

If Arnold Howard or one of the other kiln reps responds to your question,
listen to whatever they say. They have a lot more experience at this.

Bruce Girrell

_________________________________________________________________

### Mary & Wes on wed 11 jul 07

A simple answer would be that the higher the watts number the more heat the
kiln will have at it's demand. The Hertz number only starts to matter with
the controller electronics (how many sin wave cycles per second) and on some
will not matter at all depending on if there is a self regulating power
supply transformer. The cycles control the clock speed and other electronic
components, hooked to this is the fact that almost all 50 cycle systems run
at 208 to 240 volts (this is where the power supply comes in) the heating
coils couldn't care less. But even most 60 cycle kilns will be using 208 to
240 volts due the better use of power because all the legs of the current
flow are used (remember the sin wave). Be sure to ask lots of questions
until you feel you understand what the dealer is trying to tell you.

### Snail Scott on thu 12 jul 07

>Date: Tue, 10 Jul 2007 20:14:31 +0100
>From: May Luk
>Subject: Kiln Specifications - The Watts and The Hertz

>1- What are my concerns whether the numbers are high
>or low? Say two 30 Amp kilns; Kiln A is 5500 Watt and
>Kiln B is 7200 Watt. What is the difference from a
>user's point of view?

2-Ditto with Hertz

Kiln B will use 1700 watts more power on high. It
may be able to fire faster or hotter, though, just
as a 100 watt lightbulb burns brighter than a 60
watt bulb. (The exact amount of extra 'brightness'
will depend somewhat on the efficiency of the
design, though.) Watts are the unit of power as a
quantity; your electric bill charges you per watt.
A standard 10-sided kiln uses about 10,000 or
12,000 watts on high. All else being equal, B is
a higher-powered kiln.

When you say 30 amps, is that printed on the kiln?
Or is it the size of the breaker on the circuit?
Just wondering, because volts x amps = watts. If
it's running on 220 volt power, at exactly 30
amps, for example, that's 6600 watts.

You never want the breaker to be the same number
as the rated amps on the kiln. Amps is the 'size'
of the power, and it can vary a little while firing
due to resistance of the elements, so always have
a slightly bigger breaker than the rated amperage
of the appliance.

Hertz is the frequency of power. (Think of it as
the 'flavor' of the electricity.) For any normal
usage, whether household or business, if it comes
out of the wall, it's 60 hertz. Always. You don't
get to pick; it's the only kind you can get.
Manufacturers are required to state the hertz
that the the device uses in its specifications,
but you will never see any hertz but 60 for a
plug-into-the-wall item, and that includes kilns.

-Snail

### Gregory Evans on thu 19 jul 07

Hertz is a unit of measurement for frequency.
Watt is a unit of measurement for power.