Why does the e23T go to Cone 10 but the e28T only go to Cone 8?

Why does the e23T go to Cone 10 but the e28T only go to Cone 8?

There is an electrical code rule in the US that allows you to have any appliance that draws 48 amps or less not have what are called "branch fusing". Branch fusing is where there are fuses for each separate circuit in the kiln. We do this on our larger Jupiter kilns, DaVinci kilns and eQuad-Pro kilns for instance. The extra fusing makes the control panel larger and the kiln more expensive. Also the 40 amp limitation allows us to provide the kiln with a 50 amp plug which most people find convenient over direct electrical hook up.

Also, a 48 amp fuse requires a 60 amp circuit breaker because the National Electrical Code states that you must have 125% higher fuse or circuit breaker size for the device than the amperage of the device.

All Easy-Fire kilns use this 48 amp code restriction, so they do not have branch fusing. For all models, except the single phase e28T kilns, 48 amps is enough power in the kiln to allow the kiln to reach cone 10. In the single phase e28T, however, the number of watts per square inch of inside kiln surface area is much less than in the other models and is not enough to reach Cone 10. This is also true for the same reasons in our competitors' kilns. (See here for more information)

If you have three phase available we are able to increase the number of watts while still staying below the amperage limitation. (By the way not every kiln manufacturer takes advantage of this ability of three phase to carry more watts).

The other recommendation, if you need Cone 10 operation and can't get 3 phase (which is hard to get in a residential installation) and want a 10 cubic foot kiln, is to get an eQ28T (eQuad-Pro) or a JD2927 (Jupiter). The single phase versions of these kilns will easily go to Cone 10. You will need a larger electrical circuit to run these kilns however.