(1)A person sentenced to service detention—
(a)may be detained in service custody; but
(b)may not be detained in a prison.
(2)Subsection (1)(a) does not apply if—
(a)the sentence has not taken effect; or
(b)the sentence has ceased to have effect by virtue of section 290 or 291 and has not resumed effect.
(3)A person detained in service custody in pursuance of a sentence of service detention is deemed to be in legal custody.