Electrical System Inspection

In my last post, I described the physical condition of the kiln.

I later realized, by reading the reactions to my posts, that I must have sounded really whiny, complaining, and dire.  That was not my intent. I was just trying to convey that initial "oh crap" feeling I had.  Sorry everyone ! :-)

Today, I am going to cover the electrical systems, which is the heart of the kiln.  Then in the next post, I will start to cover the repair and rehabilitation processes.
 

Again, here is a picture of the kiln after I unloaded it into my driveway. Notice that the kiln sitter control system has separated from the kiln itself.  This will not be a problem, as I intend to install a digital control system in the kiln.  I plan to use the kiln sitter control box, to house the Type K Thermocouple in the new configuration.

The main control panel of the kiln looked to be in good shape.  So I took the control housing panel off and inspected the majority of the electrical internals of the system.
 

At this point, most people would have been in a more severe "Oh Crap" mode than I was when I inspected the exterior of the kiln.   Thankfully, I'm an Electrical Engineer and to me, this is the simple part of the rehab process.

It was not in good shape.  There was literally a rodents nest of some sort in the bottom.  And the aforementioned rodent had decided that the wiring had looked like a good snack at some point in time.

There was also significant deterioration in the insulation of other wire segments.  Some of the insulation  literally came off in my hands when I touched it.  This was not totally unexpected given the age of the wiring and the operating temperature of the kiln (even the outside, in near proximity to the walls).

The Paragon A-88B Kiln consists  of 4 separate heating elements, controlled by two 4 position switches, and the associated wiring.
 

This picture show how the elements exit the side of the kiln and are connected to the control system.  My Aunt originally told me that there were two elements in the kiln and "one" did not work.  In actuality, you can see where the first and second elements were badly burned at the insulator posts, and burned the connectors away.  Once a kiln elements are heated, they become VERY brittle and prone to breakage.  I may have  inadvertently broken one of the working two, when inspecting the connections.  They were THAT sensitive, given their brittle nature and their age.  I hope to be able to heat up the ends, unravel some of the coils, and be able to hook them up again.

With Paragon replacement elements running $45 per element (x4 for this kiln) plus shipping I really do not want to have to replace them.  That would literally add +50% to my costs on this project.

At this point, I have decided to do a total re-wire of the kiln.  The digital controller replaces most of the functions of the two 4 position rotary switches, and the original wiring is absolutely UNSAFE.  If it was used in its present state, your just asking for a major shock, or a fire.

I plan to use a simple main power ON/OFF switch, x4  ON/OFF switches for each separate heating element, and the digital control system (PID controller, SSR relay, Type K thermocouple) to regulate temperature, plus all new wiring.

On the interior, there are four major places where the firebrick is broken that has to be repaired, or a short will occur in the heating element.  When the element heats, without support they will sag under their own weight, and touch the element portion below, creating a short.  This will do very bad things to your kiln.