I have added 120v outlets before, but how hard is it to add a 240v outlet
in a home? I am going to buy an electric kiln for firing pottery, and will
use the kiln on my back porch or back yard, so I need a 240v outlet that I
can run a long (~20 feet) extension cord out to the kiln. I do have a
240v outlet for my electric range that is in a wall that might be
convenient for creating a 240v on the opposite side of the wall (which is
on my porch-- ie. the wall separates my kitchen where the 240v outlet for
the range is from the porch that I could run an extension cord out to the
kiln). Any ideas? Of course it would a lot easier to just run an extension
cord from the existing 240v outlet in my kitchen outside, it is just that
I live in Minnesota USA and I am not sure how I would do this without
leaving a door adjar and letting cold air in; or could I access the 240v
circuit somehow from below the floor of the kitchen (i.e. in my basement)
and then just run a line out from the basement?
Just how many amps does that kiln need? I doubt if you can run that
and your elect range off the same circuit. I also question the "extension
cord" idea, however the answer to my question may get past that one.
Additional question, how many amps is that existing 240 outlet rated
for? Do you have available space for an additional 240 breaker in your
If you don't understand all of this, I suggest calling in a
professional, you are likely to get yourself into trouble trying to do it
yourself. It is not really all that difficult, but the danger comes in when
something is not as expected and due to lack of experience you don't notice
You will need to know what the max will be and wire for that. With 50
amps that means #6 wire. Hard to find extension cords with #6 and plugs
rated for 50 amps. I strongly suggest hard wiring and no extension cords.
I am not sure. Since the issue was extension cords, I am not sure my
numbers are correct. I would have to look it up and I don't have that
handy. I suspect someone has the info handy. In any case, I would not
consider it myself.
Some of the very small 240 V. Kilns use a 30 amp circuit. Most require
a 50 amp circuit. You need to check the requirements of the kiln that
you plan to purchase to determine what you need, if in doubt, wire it to
handle the 50 amp load.
I would not even think about running it off of the same circuit as the
range, and never run it off of an extension cord.
I ran wiring for a couple of these when I owned a ceramic shop about 20
years ago, and ran #0 wire. Can you imagine how hard it would be to
handle an extension cord with 4 #0 wires in it? :)
Your best choise would be to hire an electrician to run you a new 240 v.
circuit all the way from the box and have a dedicated breaker for the kiln.
Your going to have to run a dedicated circuit for your kiln sized for the
maximum amperage the kiln will draw (plus whatever margin code dictates).
This could be anywhere from 50 to 80 amps, depending on the kiln.
Forget about tapping into the circuit for your electric range. With all due
respect, the fact that you are even thinking about doing this leads me to
question whether you should undertake this project yourself. I feel you
would be best served by hiring a licensed and bonded professional
electrician to do the job for you. Running one circuit like this won't be
all that expensive and the piece of mind you gain by knowing the job is done
right will be well worth the money.
Are you even sure your range is serviced by 240v? (Mine isn't) You probably
need an electrician to install a new circuit box and bring 240v service to your
house. Then you can think about wiring an outlet.
I agree with Banister. Remember that 240v can kill you.
Banister Stariwell wrote:
If you are going to mess with 240 volts, get an Electrician to install the
new outlet. Also, be certain to follow the installation instructions for
the kiln to the letter. You won't want it near any flammable material.
Ranges are typically on a double 50 breaker. Your kiln probably needs a
smaller breaker than 50 amps.
As for running an ext cord, it is physically possible, but it's not safe to
run an extension cord off your range outlet.
I'd suggest call an electrician for this one.
Christopher A. Young
Jesus: The Reason for the Season
i would think twice about an 220 volt ext. cord... most electrical
equipment will not work with extension cords(the metal in them is not
thick enough... if you are using 10 ga. wire in the wall then you need a
10 ga. extension cord.. doubt you gonna get one and will only mess up
your equipment........ i know with air compressors they tell you never
to use an ext. cord, but to use a longer hose for the air... the reason
is that you gonna get voltage loss with using an extension cord.....
and this is with a 110 volt air compressor...if you get voltage loss
with a kiln you gonna have to wait longer for it to heat up and its
might not work correctly...
People make a big deal out of 240v, but really isn't any more difficult or
dangerous than 120v if done properly. Doing it properly is the key. Little
things that might not matter at 1,800w (120v/15a) can be catastrophic at
You first have to find out your electrical requirements. You say it is 21a
to 50a; well, it is very different running #10 for the 21a than it is
running #6 for the 50a. Also you have to know if a neutral is required; I
don't know why a kiln would need a neutral, but it might.
No way to price it on the internet; doing the panel connection and outlet
(or direct wiring, whatever) is fast and easy. The slow expensive part is
running the cable. That could take an hour or 20 hours depending on the
route and the cable.
In general, in North America, the electric service comes into the house in 3
conductors. 2 black, and 1 white. If you take 1 white and 1 black, they will
give up 115V. If you take two blacks, they will give you 230V. Please take a
volt-meter or multi-meter to test it out yourself.
Don't forget; Watt = Amp x Volt, therefore by increasing the voltage, you
will require less Amp (means smaller breaker and lighter wire).
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