Cabe, Toolmaker - the mfg in this case was Amana, but I found schematics from others, such as Whirlpool, who do the same thing: only switch one side of the oven element. And I'm located in the USA, where UL approves such things, apparently.
Excellent post Noor. I retired from the appliance industry before starting my company and remember the very same issues from earlier times. Now, UL requires "double line break" for 220 VAC heating elements and circuits. At one time, one leg remained "hot" even after an element or switch malfunctioned. One of the greatest problems with electric elements, bake and broil, is entrained moisture. Moisture enters and when heated, expands causing ruptures in the tubular element. The MgO acts as a "sponge" thus causing issue when water is present. In the newer ranges, DLB systems will solve this problem.
I searched out some more schematics, and the majority of them only switch one side of the oven heater element. I'm sure that some of these models had to be UL approved, so I guess it's just the industry's dirty little secret. And you really can't get electrocuted touching a live heater element if it is dry and in good condition. But the insulation layer is constantly subject to high temperatures, so I still think it's a bad design for a consumer appliance. I'm glad that I got such a good response to the article here. Maybe things will change.
I'm with you on that, which is why I'm asking about UL. There are supposed to be legal and/or monetary consequences for dangerous electrical products/components. That makes me wonder if the Whirlpool machine with the same switching pattern may also be violating UL standards. Or did something happen to consumer product oversight?
Yes, I've seen it be dangerous. But what really irked me was how the manufacturer practically went out of their way to NOT give me any help on this. They were so polite and so utterly useless. They must think it's dangerous for them just to talk about it.
I just found a Whirlpool oven schematic online that does the same thing - switches L2, but not L1. So I think that it is not required by UL, and that most, if not all, all manufacturers do it. Admittedly, you don't pull the element out for cleaning like a stovetop burner. Still, I feel nervous when I can come into contact with an element that has one side hot just by cleaning my oven, now that I've seen what can happen when the element breaks down.
Noor, thank you for posting the company name. It seems that the quality of once-great brands has really dropped way, way down. I bought a Sears Kenmore oven and fridge and a fairly low-end GR washer and dryer about 12 years ago. I still have them, and the Sears machines, in particular, still work great. I've grumbled here occasionally about the GE knobs and membrane keypads, but the basic machine parts still work well. I dread the day when I have to replace them.
Transfers the control of a large number of motion axes from one numerical control kernel to another within a CNC system, using multiple NCKs, and enables implement control schemes for virtually any type of machine tool.
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