Multi-unit pottery kiln - how hot can it go? I am inheriting an old electric kiln. It has three stackable heating elements and the data plates on each stacking ring says "Petterson Multi-Unit Kiln", I can't seem to find much about this on Google.

The data plates each specify a maximum temperature of 1950°F (1065°C), and are rated at 250V, with 10A, 10A, and 9A current ratings (each with its own cord). When all three are used together, would this kiln be capable of getting hotter than 1950°F, such as to fire stoneware or porcelain (cone 6 to 10)?

Also, is there a preferred way to test the kiln to ensure it is functioning correctly?
If the kiln is rated for 1950 degrees Fahrenheit, then that's about the highest you should fire it to.  The number of rings you use isn't a function of how hot it gets but more a function of how much space the inside of the kiln will have.

To test the kiln, you can just plug it in and turn it on, if it heats up, it works.  As BrownRedHawk stated, you should place some cones in the kiln when it fires to see how hot it gets.  Sounds like your kiln will probably easily fire to cone 06 to 04.