# calculation of electricity used per firing

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• #9231
auradror
Participant

I used to have a good way of calculating my approximate  electricty usage and costs per firing to factor into my budget and for tax purposes. I can’t seem to find it now. Does anyone have a good calculation, or link to this info? Also anyone use a meter on the  kiln plug ? I think mine is too big to put any affordable meter on. Thanks so much.

#10839
Anonymous
Inactive

Meters for 220V plugs are expensive.  Here’s one that attachs at the panel for \$250:

http://www.powermeterstore.com/p4124/eml_2020.php?p_tab=main

What kind of controller do you have?  Many of the new one’s (at least those based off Bartlett controllers http://www.bartinst.com/kiln.html) can actually tell you exactly what a firing costs if you program in the cost per kwh.

Paul
FusedGlass.Org
Helios Kiln Glass Studio
PaulTarlow.com

#10840
jim boles
Participant

Paul:

My electric co-op will let individuals borrow their meter. Perhaps other companies will do the same. They use the meters to for troubleshooting and loan them out so that their customers can calculate cost and/or look to reduce their energy consumption.

#10841
glassartguy
Participant

Here is the method that I used and it has worked out to be fairly accurate. I went out and read the electric meter for several typical days, at the same time of day and then divided the total kwh by the number of days. I then did a full fuse firing during a day. I read the kwh during that day and subtracted the difference. I then multiplied the difference times our cost per kwh. I live in the Pacific Northwest and our rate per kwh is pretty cheap compared with most places. A full fuse costs me an average of about \$4.00. A pot melt costs about \$5.00. Everything else is less per firing. I have kept track for awhile and it is pretty consistent. My kiln runs on a 220 circuit and is 18″ x 18″ x 12″ inside. I never run it without it being full although slumping stuff can be fairly inefficient. I Hope this helps.

Glassartguy

#10842
jacquibush
Participant

Here is the formula that my husband came up with – hope it helps.

This only works well with kilns with kiln-sitters and time-limit dials… (sorry) but if you happen to have an older kiln you are using an external electronic controller with, you have a low-accuracy way to track how much electricity your kiln uses easily.

Set the time limit dial to 10 hours. Fire as usual. When finished, see how many hours are left on the dial, and subtract them from 10 to get the number of hours of time your kiln was turned on. Usually you can estimate to within a quarter of an hour.

Multiply the number of hours times the cost per KWHr, times the wattage of your kiln (In Kilo-watts, so a 3600 Watt Kiln would be 3.6 KW). For example, our smaller kiln in the store runs about 3 hours, 15 minutes (3 hours + 15/60 = 3.25 hours), and we assume 17 cents/KWHr, giving us:

3.25 * 0.17 * 3.6 = 1.989, or \$2.00 per firing.

This is simplistic, of course, because we are not counting prep time, having to change elements every few years, breakage, kiln wash, fiber paper, etc. But it’s interesting that what you might assume to be the most expensive part of a kiln, namely, the power to run it, isn’t so bad after all.

Jacqui

#10843
steve worcester
Participant

Unfortunately, that calculation will only give you the cost if it was firing full the whole time. As in a AFAP situation. The elements turn on and off all the time during firing and the usage is less than hours x kiln KW capacity.

A meter is truly the only way that works, but as we see it runs about \$250+ if the controller doesn’t have that function.

Steve Worcester

http://WWW.TURNINGWOOD.COM

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