How to calculate cost of firing in an electric kiln?
This is one of the queries we receive when an artist considers to invest in a kiln. Firing cost calculation involves two major components. Cost of electricity consumed during the firing and maintenance cost.
Cost of electricity consumption is calculated as
Power of the kiln in KW x Consumption time x Cost per unit
Power of the kiln:
This detail can be found in kiln specification and is usually denoted in KW.
A kiln might take X number of hours to reach glaze or bisque firing temperature. While firing it does not draw electricity continuously. In the initial stages, it draws current only for short durations. However, towards the end, kiln starts to draw current continuously. So the kiln will consume electricity only for about 50 % of the time.
Consumption time = number of hours taken to reach glaze or bisque firing temperature x percentage
Cost per unit of electricity:
This varies by region and type of connection you have. The type of connection can be Industrial, residential and commercial. Average cost per unit across country for residential connection is about Rs 8 and commercial connection is about Rs 11 and industrial connection is about Rs 6.
- Power of this kiln is 8 KW
- Firing time for cone 6 = 9 hours . Consumption time = 4.5
- Firing cost in residential connection = 8 x 4.5 x 8 = Rs.288
Kiln has wear and tear components like elements, thermocouple and relay. The cost to replace these components also collectively contribute to the firing cost. From our experience, thermocouple need replacement after about 100 firings. Relays need replacement after about 600 firings in a single zone kiln and more often in multizone kilns. Elements need replacement after about 150 cone 6 firings or 300 cone 04 firings.
This cost varies based on the kiln models, number of thermocouples in the kiln and placement of elements. For Skutt KM-822, this cost would be around Rs 100 for Cone 04 firing and Rs 160 for Cone 6 firing.
As noted above, cost to replace components is not negligible, hence when calculating the cost per firing one should consider overall cost of operation and not just the cost of electricity.
- Ganesan Manickavasagam