I'm not so much "upset" as simply concerned. :) It's not a matter of code "in my area"--It's a National Electric Code issue. Which doesn't actually apply everywhere in the country, and where it is used, it is subject to however your local building officials want to interpret and modify things. This is one of the main sections of the code that applies here: 400.8 Uses Not Permitted. Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following: (1) As a substitute for the fixed wiring of a structure (2) Where run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors (3) Where run through doorways, windows, or similar openings (4) Where attached to building surfaces (5) Where concealed by walls, floors, or ceilings or located above suspended or dropped ceilings (6) Where installed in raceways, except as otherwise permitted in this Code (7) Where subject to physical damage I note that section 400.7 does allow using flexible cords in the wiring of luminaires, so some use of cords may be allowable for U/C lights, depending on the UL listing of the luminaire, and the accompanying installation instructions from the manufacturer.

I use 100' of #14 with mine - OK, several feet less than that (see last paragraph below ;-) - but one of these days I'm going to swap it for #12. I think the voltage drop makes the motor labor at times. The reason I'm still using the #14 is that I want to find a 2-conductor #12 cable, and they're scarce. I may have to make one up. Been using electric mowers for over 10 years now. In addition to above advantages, corded electric mowers weigh a lot less than gas mowers. Very easy to use. No exhaust stench and I no longer wear hearing protectors when I mow. Rechargeable mowers might be more convenient, but you lose the weight advantage, they're less powerful, and you have to replace the battery every few seasons. Just don't mow after dusk. Every time I've run over the cord, it's been when I was trying to finish in failing light.

Go to the Grand Brass Lamp Company online and order the round SVT pendant cord in black or white. Then order some BG500 strain reliefs for the ends, in black or white. The strain reliefs will grip the cord and thread into standard 1/8" pipe fittings. They will also have sockets, nipples, couplings etc, everything you need to do it right.

Most extension cords are 16 gauge, including a lot of the outdoor ones that look fat. Better ones are 14 gauge. Expensive ones are 12 gauge. Sometimes the capacity or gauge is embossed on one of the plug ends, the cord, or printed on the tag that came with the new cord. In any case, if you're only going 50' and have a total of 300 watts, it's no problem. Below is a good link on extension cords. It says 16 gauge can handle 1625 watts if it is only 50' long. Just remember that you don't want the cord or the ends to be lying in snow or water. Here is a link that might be useful: UL - extension cords