Related Rule
New Zealand
Practice Relating to Rule 42. Works and Installations Containing Dangerous Forces
Section B. Placement of military objectives near works and installations containing dangerous forces
New Zealand’s Military Manual (1992) provides:
While parties to a conflict are required to avoid locating military objectives in the vicinity of such protected works or installations [containing dangerous forces], they are nevertheless permitted to erect such emplacements as may be necessary for the defence of the protected installations. These emplacements shall be immune from attack, provided they are not used in hostilities except in defence of the protected work or installations. Their armament must be limited to weapons capable only of repelling hostile attacks against the protected works or installations in question. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, §§ 521.4 and 633.4.