I've been thrown that one a bunch of times too. Most of the time they're under the impression that their power bill would be 1/4 the price, since 480 volts draws 1/4 the current of 120 volts - that's when I take a deep breath and collect my thoughts
Sure would like to find the guy / guys spreading this trash and send them back to their Planet of origin
So, after covering the 'ol "wattage is wattage" scenario to some degree, the next Q is almost always the "Why can't I have 480 VAC 3 Ph at my house?", with the trailing addendum Q of "That's why big companies use it, right?"
Since this is a no-win situation to explain and by this time your set up for failure, because you are not copletely agreeing with the bunk baloney - plus you have unknowingly insulted the person's tech mentor [cross out tech mentor and add the person[s] responsible for spreading the bull poo-poo electrical tech], here's one way to settle it concisely.
Give them these examples:
1:Industries use high horsepower machines which are normally running all day, night, or both.
2: Those loads are commonly located over 100 feet [wire length] from the service equipment - not to mention the transformer,
3: They pay the same as any customer - KWHs! [unless bad PF penalties are included, then they pay MORE!!!],
4: Not very many 480 VAC television sets, VCRs, Home Audio Systems, Refrigerators [residential use], PC power supplies, Vacuum sweepers, decorative lights, residential washers/dryers/irons, hair blow dryers, [you get the hint] are made that I know about. Typically when someone plugs these devices directly into 480 VAC, they run for a minimal time before all the smoke flows out of it - then someone has to sweep up the smoke!
5: 120 VAC is already a high enough voltage to ground for me! Maybe daredevils, thrill seekers and stunt persons with death wishes would enjoy living around a higher voltage to ground, not me.
6: Equipment for systems above 150 VAC to ground / 300 VAC L-L is large and expensive,
7: I could never run the amount of equipment at one time which would benifit from a 480 VAC system [nor could I afford to buy it],
8: The only thing I would have which uses 3 phase power would be a CNC machine, or maybe a big as* surfacer! Once again, there's not too many 3 phase hair blow dryers used in the common person's home,
9: The Utility company's Design Engineers would be laughing so hard at this request for a residence, they would certainy distribute an interoffice/WAN E-Mail joke message to the entire staff about this, and include your name, customer info, plus a possible picture [real photo or cartoon].
Some of these examples are extreme, but gives you enough "ammo" to fire back with.
It can be easilly summed up in one word: "Why???"