A magistrate shall be authorized to exercise the powers conferred on magistrates by this title only in the magisterial region or regions for which he is appointed, except that a magistrate may issue search warrants in accordance with the provisions of Chapter 5 (§ 19.2-52 et seq.) throughout the Commonwealth. A magistrate may exercise all powers conferred on magistrates by this title throughout the Commonwealth when so authorized by the Executive Secretary upon a determination that such assistance is necessary.