Older strings had fewer lights, and higher wattage, some in the 7 - 15 watt range. If you strung five twenty light strings together, you could have a 700 to 1500 watt light string. You might see that sort of thing on someone's massive outdoor Christmas Lights as a competitive sport display. (I know of one in my area that was reported to have a 100,000 watts of total draw! The guy has a separate commercial electric service just for his Christmas lights.) The little ones are much more rational. You don't need to read by the light of the Christmas Tree! Heck, you could probably get a tan from that guy I mentioned!