As far as the appliance itself one could use jumpers from the meter base and the appliance wouldn’t care as long as it had current flow. The overcurrent device is installed to protect the conductors not the appliance so it wouldn’t care if it was wired straight to the transformer. Believe it or not but that surge protector or plug strip with the radio/tv/whatever plugged into it don’t care either but the owner might when the insulation starts smoking. These devices are one of the leading causes of fire in our homes today so why put them to the test?
In commercial and industrial installations all duplex receptacles are to be calculated at 180 volt amperes each. The reason for this is that one will not be installed unless it is planned on being used. In a dwelling unit we must install receptacles per 210.52 at regular intervals. These devices are sometimes never used so there is no need to figure them at 180 volt amperes each but instead at 3 volt amperes per square foot.
All of this thinking of 20 ampere circuits for dwelling receptacles and separating the lights from the receptacles comes from commercial and industrial installations. The adage was passed from the commercial trade to the residential trade through commercial electricians that only did commercial and industrial installations then one day doing a dwelling and using what they had learned.
A quick look at 210.21 through 210.23 one will learn that if a 15 amp receptacle is being installed then the maximum load that can be plugged into it is 12 amps and it doesn’t matter if it is a 15 or 20 overcurrent device.
So what does one gain by installing 20 amp circuits and not installing 20 receptacles? Nothing. What does one gain by installing 20 amp circuits and 20 amp receptacles? The cost of the 20 amp receptacles are twice that of 15 amp receptacles. Their only gain is more cost and a waste of our natural resources.
So is the 20 amp circuit for a dwelling unit better than a 15 amp circuit? It depends on who you talk with. Those that I talk with say no the 20 amp circuit is more dangerous than a 15 amp circuit. These are some of the greatest minds in the electrical trade not some master electrician that has retired nor is it some unfounded wives tale that was started many years ago. It is those who are charged with writing, testing, and researching the codes and installations for electrical energy.