
(or, how to speak “electrician”)
This is intended to be a guide for selecting a kiln and to understanding the power available at your location. It is not to be taken as an authoritative or definitive document. If you have any concerns or questions about the circuits in your location, please consult a qualified electrician and your local electrical codes before playing with the electricity.
Within this document:
- General information about electricity
- General information about kilns and electrical requirements
- Ordering a kiln for your current location
- Ensuring a proper electrical fit when you have purchased a used kiln, or have moved your current kiln to a new location
- Some things to consider/know/have awareness about
- Proper Electrical Kiln location for electrical considerations
Very helpful link: Great Lakes Clay “How to buy a kiln” greatclay.com
Fraser, Harry. The Electric Kiln: A Users Manual (Ceramics Handbooks). Philadelphia, PA: University of Pennsylvania Press, 2000.
Ritchie, Ralph W. Electric Kiln Handbook. 2nd ed. Springfield, OR: Ritchie Unlimited Publications, 1996.
General Information about Electricity
Here are some simple definitions to better understand electricity. More... Amperes (A)-The measure of current, which is the rate or strength of electrical flow. When amps and volts are considered together they describe power flowing, which is the watts. volts x amps = watts Watt (W)-A unit of activity or power corresponding to the rate of work represented by a current of one amp under a pressure of one volt. Electric power is measured in kilowatts,1 kilowatt=1000 watts. Resistance (R)-The degree of resistance to the passage of current is measured in ohms (Ω). Here is an analogy to explain volts, amperage, and resistance: If there is a pipe full of marbles, the force used to push the marbles through the pipe is what electricians refer to as volts. The number of marbles counted in a cross-section of the pipe is what electricians refer to as amperage. The friction inside the pipe that causes the marbles to flow slower is what electricians refer to as resistance, which is measured in ohms. Single-phase vs. 3 phase The number of phases relates to how many wires come from the power company into your location. In general, a single-phase is in residential applications, while the three-phase is in commercial/industrial applications. Single-phase: Single Phase 110V: There are three wires, one has power, one is neutral and one is the ground. Single Phase 220V four wire: If your kiln cord plug has four prongs, you have a four wire kiln. Two of these wires are for power (red, black), one wire is neutral (white), the last wire is ground (green). This arrangement allows the kiln to use either 220 volts or 110 volts to the kiln elements. Single Phase 208V four wire : This uses only two powered wires of the 208V three phase circuit and the ground. These show up in schools that have three phase panels. Single Phase 220V 3 wires: If your kiln cord plug has three prongs, you have a three wire kiln. Two of these wires are for power (red, black), one wire is ground (green) and there is no neutral wire. Three-phase: Generally three phase power is found in commercial / industrial buildings. It would be uncommon for traditional studio potter kilns to be three phase. It would be common for larger scale commercial / industrial kilns to be three phase. Three Phase 208V : There are typically four wires. One is ground (green) the others have power (red, black, blue). A single-phase kiln will run on both three phase and single phase power supplies, however, without a transformer a three phase supply will only provide 208 volts, not 240. A 240 single phase kiln can usually be run on 208 single phase. Running a 208 single-phase kiln on 240 usually requires new elements. You should consult the manufacturer.
General information about kilns and electrical requirements
Voltage requirements for kilns.More... Before installing a new outlet for a kiln consider the largest amperage that you may ever want at that location. Also, consult a kiln manufacturer’s literature. They often specify a larger wire size than the default size suggested by electricians. In your electrical panel, you need the designated circuit breaker to be 20-25% greater than the amperage required on the kiln. This is a code issue, and you need to research this percentage – ask your licensed electrician. 208 volts: 208 V is different than 110v and 240v. It is most often found in schools, industrial settings, or residences where industrial power is available. A 240v kiln can be fired in a 208v supply, however, it will take longer because the supply has less power. Most kilns can be ordered in 208v instead of 240v if this is what your supply requires. A kiln equipped with 208-volt elements is not as forgiving when applied with a 240-volt power source (element life may be shortened). 120 volts: A quick note about 120-volt kilns. Residences with 240-volt service and schools or businesses with 208-volt service all can accommodate kilns firing at 120 volts. Some test kilns, generally with only one element, run on 120v. Amperage requirements for kilns This will be expressly stated in the literature about the kiln and on the kiln itself. (If there is not a plaque near the electrical components, when the kiln is unplugged, open the protective cage around the electrical panel and look inside). On older kilns, you may have to locate a kiln identification number and call the manufacturer to obtain the information. In your electrical panel, you need the designated circuit breaker to be 20-25% greater than the amperage required on the kiln. Generally, kilns that draw more than 48 amps do not come with plugs; they must be wired directly into your power supply.
Ordering a Kiln for Your Current Location
The three things that you need to know when ordering a kiln are available voltage, available amperage, and whether you have single or three-phase capability. Your electrician can answer all of these questions. A service call should cost around $50 dollars (depending on your location). Call and get some price quotes, some electricians will deduct the fee for the service call from any future work that the installation will require.More... Consult your electrician to determine the voltage at your location. There generally are two voltage services available; 240 volts and 208 volts. If the kiln is to be used in a home, it will likely use 240 volts. This is the service provided to private residences by the electric company. Schools and industrial buildings usually are supplied with 208-volt service. Both voltage systems use the same wall outlets, so you can’t tell voltage by the type of outlet. Test kilns: Most 110 electric outlets are meant for less than 15 amps. Some test kilns draw near 20 amps. For these, a dedicated outlet should be installed. There should be no other devices on the circuit. Available Amperage Consult your electrician to determine the available amperage at your location. Make sure that the total amount of amperage available is enough to run all of the equipment and fixtures, (including your new kiln) you will be using. Increasing the amperage supply to your building can be very expensive. When purchasing a kiln, make sure you are not going to exceed the available amperage. Single or Three-phase Consult your electrician to determine what type is available for your location. The general rule of thumb, residential is a single phase and commercial is three-phase. If a building is equipped with a single-phase service, the kiln must be wired for a single phase. However, with buildings supplied with three-phase power, you can choose between a single or a three-phase kiln. In general, there are no advantages to buying a three-phase kiln to elements or your firing. If you are purchasing a three-phase kiln, you may want to research why this is a better choice for you.[/read]
Similar to ordering a new kiln, the three considerations are volts, amperes, and single or three-phase. However, rather than having a kiln built to specifications, all of the variables are determined by your location and the kiln in your possession. You need to establish if the electrical supply will complement the electrical requirements of your kiln, and if not, what will remedy the situation. More...
Ensuring a Proper Electrical Fit at New Location
Be Aware of these Facts
The Right Location
When choosing a location for your kilns try and stay within a 50 ft wire run from your breaker box. If it is necessary to run the power farther than 50 ft you will need to increase the wire gauge to the breaker box.More...
Solar Electric Kilns
“Some occasional ramblings about solar power with regular statistics on energy produced by a system in Canterbury UK.”
This is a blog from the UK about firing electric kilns with solar power:
solar-power-experiences.blogspot.com