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House wiring needed for kiln


#1

All,

I have a Paragon miniature kiln, inner chamber a 5 inch cube, that
takes 117V at 15 amps.

I bought the kiln planning to do enamelling with it and maybe even to
fire some porcelain elements and even glass beads.

The directions on it specify to never use an extension cord with it.
Unfortunately, my entire shed is powered by an extension cord about
80 feet away from my house, which means that I can NEVER run my kiln
in side the shed with the present wiring.

I understand that since a kiln operates for hours at a time, I would
need thicker wiring than usual so that it would not overheat under a
continuous duty electrical load.

I’ve talked this over with local electricians, and I’ve come up with
this:

I’m planning to run a 60 amp breaker from the house using #6
three-conductor wire via Schedule 8 PVC underground conduit, per
local code.

I would then run this to a local panel that I would install in the
shed, each of them with a 15 amp breaker wired to respective outlets
for the kiln, lights, space heaters, and intermittent duty power
tools.

That way, I could plug the kiln into an outlet and be done with it.
Total cost for the work would be about $500, not counting permit.

Can anyone with kiln or electrical experience tell me what is missing
in this picture?

Thanks,
Andrew Jonathan Fine


#2

Not a good thing to ask me, Andrew. My “experience” with electrical
was via a knitting needle into the stove outlet when I was 2.


#3

Andrew, I have Paragon Programmable kiln which I use for wax
burnout. I suggest you contact Paragon. They have a wonderful support
system and will answer all your questions.

If you log onto their web site, on the menu you will find "Ask the
kiln Guru " Just email them your question and you will get a prompt
answer. They also put out a weekly email filled with all kinds of
valuable so ask to receive it. Programming a kiln was
new to me and I simply deluged them with questions, all of which
were answered promptly.

Alma


#4

I would suggest that you use 20 amp breakers and do all the wiring
from the panel box to the outlets and lights with 12 gauge wire. 15
amp breakers and 14 gauge wire are fine for most things, but you
never know where you will be going in the future. The labor is the
same for either set-up, but the extra expense for heavier wire will
only increase the cost from about $40 for 100 ft of Romex 2/14 to
$51 or so for Romex 2/12. If you use a BX cable (metal sheathed) the
price goes up from $61 for 100 ft. 14 ga to $101 for 12 ga. The
difference in the cost of the breakers is minimal.


#5

Andrew,

You are talking about adding a sub panel in your shop…this is
common. The kiln does not care what it is plugged into as it simply
eats electricity and will do so until its cycle is completed or it
overheats its feed wires, but what you are about to do seems good to
me.

Be sure the #6 is rated for your application
(distance,insulation,placing in a pvc pipe underground) and I
suggest new main in the panel you are placing in the shed. Keep in
mind your actual draw of power my be less than your assumed 60 amp
and work within the new power delivered. A general rule is that main
breakers should be loaded to 80% their number rating so a 100 amp
main panel is to be run to 80 amps total…something to keep in
mind and something rarely discussed.

It is also possible to turn on and off the lights with a “Switched
breaker”…if you are to flip breakers on and off frequently they
should be switched breakers.

Ric


#6
... 117V at 15 amps (...) run a 60 amp breaker from the house
using #6 three-conductor wire via Schedule 8 PVC underground
conduit, per local code. I would then run this to a local panel
that I would install in the shed, each of them with a 15 amp
breaker wired to respective outlets for the kiln, lights, space
heaters... 

Andrew, I had the same problem in my garage.

Are you running the #6 directly from a 60-amp breaker on your
current panel? Do you have enough unused juice in your original panel
to supply 3 more outlets at about 120V? If not, you might need to
contact the local utility for an upgrade.

Lorraine


#7

Andrew,

with a 15 amp breaker wired to respective outlets 

If your kiln uses 15 amps, the plug and wiring and breaker should be
a 20 amp circuit instead of a 15 amp circuit.

John
The Jewelry Equipment Dr.


#8

Going by basic electric code that looks good as long as your base
breaker panel can handle the 60amp sub service. Good decision,
sooner or later, you would have melted down a couple of extension
cords or outlets with your prior arrangement.

Ron Charlotte – Gainesville, FL


#9

Stephen’s advice that you use 20 amp breakers is excellent. Someday
you might want to get a larger kiln, or another piece of equipment
that requires more amps than the17 you are planning on. I was really
fortunate when I got my Paragon that I already had a 20 amp breaker,
or I would have run into some expenses to have an electrician come
out to install it. Alma


#10

Hi Andrew,

lectrical standards are different where I live in Australia because
our electrical wiring is based 240V or 415V (3 phase). I have my kiln
in a shed out back and I had a 40 amp breaker fitted to the main
switchboard and about 15 metres of 4.5 mm2 three core cable run
underground to the shed which was fitted with a sub board with a ELCB
switch and, two 20 and one 10 amp circuit breakers One of the 20 amp
breakers was connected to a 15 amp outlet on the sub board. The other
20 amp breaker was connected to the power outlet circuit of the shed
and 10 amp breaker to the lighting circuit. Theoretically I would
trip the breaker on the main switchboard before loaded all three
circuits to the maximum This is rather unlikely. I installed a
separate ELCB on the shed circuit so that if it trips the house
doesn’t lose power and if the house one trips the shed doesn’t lose
power. My kiln is larger than yours with a 300mm cubed internal
volume and 3 kilowatt element which draws 15 amps. It is used both
for pottery and investment casting. I use a gas furnace for melting,
but I do have sufficient electrical capacity to run a small electric
melting furnace in the future if I wish. When I used the kiln in
rental accommodation in the past I had to use a 10 metre 15 amp
extension lead. It got fairly warm but nothing more dramatic
happened. The current sub board and plug setup behaves just fine. If
I experienced excessive heating of the plug and socket I could have
the kiln directly wired in through a switch.

All the best and have fun enamelling.

BTW I usually torch fire my enamels but I don’t do a lot of
enamelling right now. Maybe in the future I’ll get a small kiln for
my inside clean studio space. With 240 V wiring we can run one of
these from our normal 10 amp power points.

Cheers
Jenny


#11

You need to drive an 8’ grounding rod and connect it to the remote
sub-panel. You can drive the rod on a 45 degree angle, making it
easier to get into the earth.

Dennis Fisher


#12

Make sure that the electrical system is grounded at the service panel
in the studio and that only copper wire is used. The clearance for
the service panel in the studio is; clear 30 inches wide and 36
inches in front clear to the floor. This is the requirement from the
NEC. The code number I believe is 110.3. If you have a question
please let me know.

George in Green Bay


#13
I have a Paragon miniature kiln, inner chamber a 5 inch cube, that
takes 117V at 15 amps. 

A few things to consider.

  1. The standard current ratings as given in the Code are for
    continuous duty, no need to adjust for that.

  2. Don’t install 15 amp circuits, use 12 gauge and 20 amp breakers.
    Minor extra cost.

  3. You might consider running 220 volts to the subpanel. It requires
    another wire, but you can split into 110 volt circuits at the
    subpanel, and the main feed can use smaller wire since it carries
    half the current in each leg. Then you can install a 220 volt circuit
    if you ever need it.

  4. Consult a qualified electrician. (I’m not one, but my father was
    one of the best.)

  5. You may or may not need to get the job inspected, depending on
    where you are.

Al Balmer
Pine City, NY


#14
Make sure that the electrical system is grounded at the service
panel in the studio and that only copper wire is used. The
clearance for the service panel in the studio is; clear 30 inches
wide and 36 inches in front clear to the floor. This is the
requirement from the NEC. The code number I believe is 110.3. If
you have a question please let me know. 

Not sure about the extra ground rod. I spent 30+ years in Ontario.
Their codes were so complex that you would have your knickers so
twisted that you couldn’t breath. I still follow those codes even
while living in Vermont where there are no codes except avoid sparks
and fire and other bad things. My old habits die hard, drives my dad
crazy.

jeffD
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand


#15

I just ran across this:

“So after 2008 in a detached building, it is required to run 4-wire
(in new construction) to a subpanel plus install grounding electrodes
to the separated ground bar, not the neutral.”

Sounds like the 2008 NEC changed the rules, and I haven’t even seen
the 2011 code. Better check with someone who knows for sure - your
local inspector is usually glad to answer questions.

Al Balmer
Pine City, NY


#16

Hi Jeff,

Not sure about the extra ground rod 

Here’s why one wants the ground rod at the sub-panel. The reason for
the need for the sub-panel is that the run from the main panel is too
long. For that same reason, if there’s a fault, a short or whatever,
the electricity looks for the closest (easiest) ground, and that
might be the person using the electricity. There is a good ground,
presumably a grounding rod back in the earth below the main panel,
but it’s a ways off. It may find a better one in the user standing on
concrete or earth, or touching a pipe, etc. But if there’s a ground
rod in the earth close to the sub-panel it will likely go there.

This is cheap insurance and is a code requirement here.

Regards,
Dennis


#17

Even if you put in another ground rod you will still need to make
sure you have a ground wire connected between the two ground rods.
If you do not do this there is a good chance of ground surges from
near by lightening strikes. When lightening strikes it creates a
ground surge of current that travels through the ground from the
point of the strike. The voltage differential can be thousands of
volts between two ground rods separated by only a few feet. The
difference in voltage between the two will cause a current flow
between them in the only path they can find which is your house
wiring. This is enough to cause serious damage to your wiring
including starting fires. To prevent this run an external ground wire
of #4 or #6 gage between the two ground wires and then the discharge
will use this wire instead of your house wiring.

I was a radio engineer for many years working at sites with multiple
grounds and they were always required to have the ground rods
connected to each other directly.

MJ


#18
The difference in voltage between the two will cause a current
flow between them in the only path they can find which is your
house wiring. This is enough to cause serious damage to your wiring
including starting fires. 

Something like this happened to us a few years back. During a
thunderstorm, we smelled smoke in the house – the acrid kind that’s
like ozone. It was highest in the area under the stair near the well
retaining tank.

I think the breaker flipped; I don’t remember. Maybe we flipped it
or shut off the main. (I’m the daughter of a long line of electrical
contractors; checking breakers is in my blood. :slight_smile: ) There appeared to
be no other action to take, as no fire was apparent. (We do have
a/b/c fire extinguishers throughout the house.) We checked that area
repeatedly for hours after, as smoldering fires can go on and on
unnoticed if they get into a big house beam.

A heads-up was that we had electric power but no water pressure. The
electrical wiring from the retaining tank runs out to our well 50
yards away.

Next day, we went outside to examine the wellhead. I was expecting
to see melted metal. No apparent damage! Nor to nearby trees, utility
pole, house, roof, chimneys, etc. (Though trees hit by lightning can
appear mostly normal for a year or two before they finally die.) No
aroma of burning.

Nonetheless, the well pump AND ALL OF THE UNDERGROUND WIRING between
well and house had to be replaced. A colossal inconvenience that
could have been a tragedy.

My best guess, as we live in the woods, is that lightning hit a
nearby tree, traveled down, and “jumped” to the 300-foot-deep metal
shaft that houses our well-water line and the housing for its wiring.
I presume they acted as the main grounding mechanism. I’m guessing
that the metal housing for the well wiring was the conduit to the
house. Or maybe the underground water pipe, which dates to 1981 and
could well be copper.

The gentlemen who replaced our well said they hear quite often about
wells and well-wiring going kaput after a thunderstorm, with no
obvious nearby damage.

Lorraine


#19

I recently had dedicated wiring run from my electrical box to one
outlet in my basement studio and placed on it’s own dedicated
breaker. They provided me with a 4 plug outlet and made sure the
system could handle running two 110 watt kilns. They also did a
thorough inspection of the wiring box, grounding of the house & the
box itself, etc. assuring me I was working within safe parameters for
my home studio needs. My kilns are not real large, but one of them is
probably 30 years old so I was concerned about the wiring, and I had
just replaced all the coils inside of it. Interestingly, the coils
cost more than the electrician did.

When the electrician company came out to give me an estimate, they
did that so for free, and the total charges only came up to $125.00.
The man also inspected the wiring on the older kiln, and checked to
make sure it was functioning well, had no shorts in it and was a
sound device. (This was at no additional charge). I was very
surprised that the cost was actually so inexpensive. When they came
back to do the work after giving me the estimate, they were here for
maybe a half hour and they provide a full guarantee.

I know to some people an extra $125.00 can be a large expense but it
was worth it for the peace of mind it gives me, and also to not have
my breakers blowing and needing reset all the time. There was plenty
of room in the existing power box to add a new breaker into it,
otherwise it could have cost substantially more, but you can check
your box to make sure you have an extra slot just by opening the door
and looking for space.

Cheers!
Teresa


#20

Where electricians are concerned, the peace of mind they give makes
this well worth what they charge.

RC (who does not mess with wiring)