Having spent several years as a temperature control engineer, I figured out why these things fail fairly quickly.
1. The connectors have plastic insulation that will melt at extended temperatures for an extended time. That is what happens when you first start your cook - everything is cold, and the burner will be on fully for as long as it takes to get to the 'set temperature'. That extended period of time causes the insulation to melt, and filter down into the connector itself. Then, after that cook, it cools and rehardens. That causes less surface contact the next time you start it, and it makes the connector itself hotter, because of less surface contact. At some point, enough melted insulation is in the connector to cause arcing, and subsequent failure of the connection. That is what happened to mine. In other cases, the melted insulation could prevent contact at all, which would look like a failed element. I doubt that any of these elements have ever failed - only the connections.
2. The act of installing the wood tray and removing it 'jiggles' the heating element. That causes the wiring to flex each time. We all know what happens when a wire is bent enough times. Individual strands begin to break, forcing the current into the remaining ones, which then causes a hot connection, which, uh, melts the insulation, and the cycle continues.
I heard mention of using a stainless connector on these...DON'T, even if you find them. It is not safe to have non-matching metals touching while passing current through them. That is, by definition, electro plating. The connectors will fail.
So, the whole design of the treatment of the element is at fault. The wire size is probably ok, and would have to be approved by UL in the first place. The heating element should be surrounded with ceramic near the connectors, to divert heat away from the connections themselves. Properly done, the element would simply pull out like it does on your electril range.
Proper materials should be used in the vicinity of high temperatures, or catastropic failure will result. In my job, we built thermostats for baseboard heaters, and believe me, you do NOT want to be on the receiving end of a lawsuit for failure of your materials in the intended usage.
Note that when one wire breaks off, as mine did, it may be a 'hot' wire, and may endanger you if you touch the unit. So - if you experience *ANY* heating issues, unplug it immediately, take care of your meat another way (I put my pork butt on my 4 burner grill, top down, two burners on low, for my final 4 hours). Then you can ****er with
Masterbuilt about how to fix it.
I took my element out and can see the unconnected wire floating inside the chassis. Only luck prevented it from being the hot one.
So, it is not the wire, and it is not the element, it is the design. The connectors should be true high temp connectors whose insulation cannot melt. (My insulation is a black blob in the bottom of the little aluminum box. Photos forthcoming.)
The wiring should not be flexed by adjusting the wood box. The element should be a plug-in type, and the receptacle for it should be ceramic with range type connections. If that was done, they wouldn't be replacing elements in the first place, because the elements are usually fine - it is the connectors that are at fault.
I know this is a long posting, but I've seen some dangerous suggestions already, and no mention of the real cause - the plastic insulation. I don't want anyone to get hurt, and I want
Masterbuilt to 'get it' as to what is wrong, and FIX this problem properly.
John Shotsky
Thermal engineer.
