Rewiring A Duncan Energy Saver, The Teacher kiln

[AddisonSedergren]

Hey, I have a Duncan Energy Saver, The Teacher kiln, Model No. ES 820-2. Its pretty old and my brother recommended that it should be rewired to a 4 prong 240 v cord instead of the 3 prong one that is currently attached for safety reasons and code. I would have a 240 50 amp receptacle installed on the wall. I'm just having a little bit of trouble figuring out how to properly rewire the 4 prong cord to the machine properly so that it will function and have a proper ground. Any help would be appreciated. I found a manual of the machine as well if that helps.

https://aakilns.com.au/pdf/Duncan_Kiln_Service_Manual.pdf

[Dick White]

Your kiln already has a ground - the middle round prong on the plug. A 240 volt four-wire situation has 2 hot legs (red and black), a white neutral, and a green ground. A 240 volt three-wire situation has the same 2 hot legs, the same ground, but no neutral wire. Your kiln does not use the neutral circuit, there is no place in the kiln to put it, and thus the power cable and plug have only 3 prongs. The amperage of the kiln circuit must be at least 125% of the nominal amperage stated on the electrical rating plate, but not more than 150%.

[neilestrick]

There's nothing more or less safe about 3 wire vs 4 wire. It just depends on the needs of the kiln. Having a ground is the real safety issue, which you do. As Dick said the kiln needs to be on a circuit that is 125-150% of the draw of the kiln. I think your kiln draws around 24 amps? Check the serial plate to confirm, but if that's the case it should be on a 30 amp breaker.