Before responding save yourself the trouble of telling me the elder can't be or shouldn't be left alone. That's not the question.
It is my goal to make the house as safe as possible whether others are in the home or not. All sources of fire have pretty much been eliminating except one sticking point: The 1800 watt toaster oven. For too many reasons putting it away in a cupboard or high up out of reach are not solutions. I'm looking for anyone's experience as well as with cupboard locks--do the childproof ones on Amazon etc work for you?
We had an electrician out for another matter. His suggestion was to get a heavy duty power strip, put it in the cupboard above where the toaster oven sits, make a small hole, and run the cord from the toaster oven up into the power strip, while the power strip plug would come out and into the safety covered outlet that could not be messed with. Then the power could be cut by my using the switch on the power strip, and finally locking the cupboard.
Another electrician thinks that the new outlets he's required to install are childproof to start out with and he thinks if the toaster oven were left unplugged, mom would have a real challenge trying to plug it in the right way. But that still seems uncertain to me...still a chance...and puts us back to the insanity of her being OCD and pulling the plugs out constantly which means having to reset the microwave clock.
She is somewhat functional but needs supervision that she angrily rejects. For the most part she doesn't attempt any efforts in the kitchen, but I caught her attempting to put the kettle up for tea...clueless that the knobs were missing from the electric stove top and there was no heat source.
A gfci can be installed to be the only receptacle that is disconnected or it can be wired to disconnect other receptacles.
For the frustration of the microwave clock, just stop resetting it. Your microwave will function normally without setting the clock. I know the 'norm' is to have the clock set, but there is no reason to. Generally there is a clock on the stove and you can put up a wall clock too.
Would she attempt to remove the child covers for outlets to plug in the toaster oven?
I have one outlet in my house with this on it. https://www.amazon.ca/izHome-Universal-Electric-Outlet-Cover/dp/B01FX8836G/ref=sr_1_7?hvadid=233204803646&hvdev=c&hvlocphy=9001612&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=3521453297100202147&hvtargid=kwd-322652581339&keywords=child+proof+outlet+cover&qid=1555347310&s=gateway&sr=8-7
I am sure you have them installed, but a reminder to ensure your smoke detectors are up to date, have fresh batteries and are working.
Can you find her appliances that she IS capable of using so that she is less apt to keep trying? For example I love my keurig for coffee and it will do tea too, I can't see any way it could be used in a dangerous way.