61.— (1) In the case of a mixed supply, except where subsection (2) or (3) applies, tax shall, as appropriate, be charged on the quantity of electricity supplied for each use.
(2) In the case of a mixed supply involving household use, it shall be assumed that any quantity up to one unit of such supply has been supplied for such use during each calendar month in an accounting period.
(3) In the case of a mixed supply involving business and non-business use (other than household use), it shall be assumed that any quantity up to one unit of such supply has been supplied for business use during each calendar month in an accounting period.
