Most things that use DC use pretty low voltage, like 5 or 12 volts or so. High voltage allows you to transfer energy much more efficiently. So, for low power

Most things that use DC use pretty low voltage, like 5 or 12 volts or so. High voltage allows you to transfer energy much more efficiently. So, for low power devices it might make sense to run a low voltage line but you wouldn't be able to run high-power devices out of it unless you wire your house with really thick wiring.