4(1)Subject to the following provisions of this Schedule, a demand for arbitration shall not be effective for the purposes of section 12 of this Act if the next termination date following the date of the demand falls earlier than the end of three years from any of the following dates, that is to say-
(a)the commencement of the tenancy, or
(b)the date as from which there took effect a previous increase or reduction of rent (whether made under that section or otherwise), or
(c)the date as from which there took effect a previous direction of an arbitrator under that section that the rent should continue unchanged.
(2)The following shall be disregarded for the purposes of subparagraph (l)(b) above—
(a)an increase or reduction of rent under section 6(3) or 8(4) of this Act;
(b)an increase of rent under subsection (1) of section 13 of this Act or such an increase as is referred to in subsection (3) of that section, or any reduction of rent agreed between the landlord and the tenant of the holding in consequence of any change in the fixed equipment provided on the holding by the landlord ;
(c)a reduction of rent under section 33 of this Act.