The Merchant Shipping (Navigational Equipment) Regulations 1993

Provision of electrical energy

6.—(1) There shall be provided in every ship at all times while the ship is at sea and at all reasonable times when she is in port, a supply of electrical energy suitable and sufficient for the operation of the navigational equipment installations required by these Regulations, for testing purposes and for the charging of any rechargeable batteries which are a source of electrical energy for the navigational equipment installations.

(2) The supply of electrical energy shall not exceed the limits set out below:

AC supplies:	variation from nominal voltage of ±10%
	variation from nominal frequency of ±6%
DC supplies:	variation from nominal voltage:
	110/220V supplies, +10%, −20%
	24/32V supplies, +30%, −10%

(3) Readily accessible means shall be provided for isolating each navigational equipment installation from its source of electrical energy without causing any interruption to, or adversely affecting, the supply of electrical energy to any other equipment.

(4) Where a ship is required to be provided with two radar installations–

(a) they shall be so installed that failure of either radar installation shall not cause the supply of electrical energy to the other radar installation to be interrupted or adversely affected; and

(b) on ships constructed on or after 25th May 1982, both radar installations shall be capable of being operated one at a time, from the ship’s emergency source of electrical energy, if provided.