Electrical – How to safely add power switch to power strip

That does indeed describe a properly engineered 50 amp device.

It is normal for appliances to use slightly lighter gauge wire than would be used in building wiring. You can observe that inside electric ranges, dryers, and water heaters, where you will see the 10 or 8 gauge incoming supply wires to a terminal and then 12 or 14 gauge wire going from the terminal block off to the components.

Because the wire is inside an enclosed box, and is not tightly bundled or surrounded by thermal insulating materials, its elevated temperature will not cause any danger. It will run a little warm at peak current, but be far below "hot". The same is not acceptable inside dwelling walls were it will be in contact with wood, fiberglass, cellulose insulation, etc.

As for standards, I have determined this is beyond the scope of the NEC and falls into the domain of the National Fire Protection Association (NFPA) standards. That seems to cost $$ to view.

Without knowing the specifics of your wiring, you should be just fine running all of that and more from a single outlet. On one 15amp outlet I have running all at once a PC, PS3, 120watt AV receiver, and an LCD TV -- you'll be fine! If you do overload that circuit the breaker will trip or the fuse will blow, and you'll lose power to that outlet.

I would get a more competent electrician out to figure out what is going on with that outlet though.