29(1)For the purposes of this Schedule a “special utility scheme” is a scheme for determining when—
(a)a supply of electricity, or
(b)a supply of gas that is in a gaseous state and is of a kind supplied by a gas utility,
is treated as taking place in cases where the electricity or gas is covered by the scheme.
(2)If in the opinion of the Commissioners it is reasonable to do so, they may in accordance with the provisions of this paragraph prepare a special utility scheme for a utility or for two or more utilities.
In this paragraph “utility” includes a person who makes supplies on which levy is chargeable by virtue of paragraph 5(2) (partly exempt combined heat and power stations).
(3)A special utility scheme shall specify the period for which it is to have effect.
(4)No special utility scheme shall be of any effect in relation to any electricity or gas supplied by a utility unless the utility elects in writing to be bound by it for the specified period.
(5)If a utility makes such an election—
(a)the scheme shall have effect for the specified period in relation to such electricity or gas supplied by the utility as is covered by the scheme, and
(b)during the specified period the scheme applies to determine when a supply of a taxable commodity is treated as taking place if the commodity is electricity or gas covered by the scheme.
(6)A special utility scheme may—
(a)cover all or any of the electricity or gas supplied by a utility for which the scheme is prepared;
(b)provide for paragraph 36 or 37 not to apply, or to apply with modifications, to electricity or gas covered by the scheme.
(7)The Commissioners may by regulations make further provision with respect to special utility schemes, including (in particular) provision amending this paragraph.