Despite anything else in this part, the powers of an authorised person under this part in relation to entering a place are not exercisable in relation to any part of a place that is used only for residential purposes except—
(a) with the consent of the person with management or control of the place; or
(b) under the authority conferred by a search warrant; or
(c) for the purpose only of gaining access to a suspected workplace, but only—(i) if the authorised person reasonably believes that no reasonable alternative access is available; and(ii) at a reasonable time having regard to the times at which the authorised person believes work is being carried out at the place to which access is sought.