The power supply cord originally supplied with K18 kilns is only a three-wire cord. The third wire is actually a "neutral" wire, not a ground wire. The original literature for these kilns said to ground the kiln by running another copper wire from each section of the kiln case to a cold water pipe in your home.
With today's electrical standards, the grounding is done through the same power cord that the power comes in on. If you have not already done so, you should replace your power cord with a 4-wire power cord, either hardwired to the supply or with a NEMA 14-30 plug- outlet configuration. You may need to hire an electrician.
The danger is that if the kiln is ran with the 3-wire cord, and a wire in the control box somewhere comes off it's connection and touches the inside of the metal box... nothing will happen until you touch the box and become the pathway to ground for the electricity. Once the kiln is properly grounded, the circuit breaker will trip as soon as the wire touches the inside of the box.