SOLAS Regulations on Public Address systems on Passenger Ships

            This Regulation comes under SOLAS Chapter III, Part B - Requirements for ships and life-saving appliances, Section I - Passenger Ships and Cargo Ships, Regulation 6 - Communications.

General Requirements:

• A Public address system or other means of communication shall be available throughout the accommodation, service spaces, control stations and open decks.

• The public address system shall be clearly audible above the ambient noise in all spaces and shall be provided with an override function controlled from one location on the navigation bridge and such other places on board as the Administration deems necessary, so that all emergency messages will be broadcast if any loudspeaker in the spaces concerned has been switched off, its volume has been turned down or the public address system is used for other purposes.

• On passenger ships constructed on or after 1 July 1997: 
• The Public Address System shall have at least two loops which shall be sufficiently separated throughout their length and have two separate and independent amplifiers.
• The Public Address System and its performance standards shall be approved by the Administration having regard to the recommendations adopted by the Organization.

• The public address system shall be connected to the emergency source of electrical power.

• Ships constructed before 1 July 1997, which are already fitted with the public address system approved by the Administration which complies substantially with those required by the Regulation.

Requirements on Performance Standards for PA Systems:

• The public address system should be one complete system consisting of a loudspeaker installation which enables simultaneous broadcast of messages from the navigation bridge, and at least one other location onboard for use when the navigation bridge has been rendered unavailable due to the emergency, to all spaces where crew members or passengers, or both are normally present and to assembly stations (i.e. muster stations).

• The controls of the system on the navigation bridge should be capable of interrupting any broadcast on the system from any other location on board. It should not require any action by the addressee.

• It should also be possible to address crew accommodation and workspaces separately from passenger spaces. 

• In addition to any function provided for routine use aboard the ship, the system should have an emergency function control at each control station which:

• is clearly indicated as the emergency function; 
• is protected against unauthorized use; 
• automatically overrides any other input system or programme, and 
• automatically overrides all volume controls and on/off controls so that the required volume for the emergency mode is achieved in all spaces. 

• The system should be installed concerning acoustically marginal conditions so that emergency announcements are clearly audible above ambient noise in all spaces where crew members or passengers or both are normally present and to assembly stations (i.e. muster stations). 

• With the ship underway in normal conditions, the minimum sound pressure levels for broadcasting emergency announcements should be: 
• in interior spaces 75 dB(A) and at least 20 dB(A) above the speech interference level; and 
• in exterior spaces 80 dB(A) and at least 15 dB(A) above the speech interference level.

• The system should be arranged to prevent feedback or other interference.

• The system should be arranged to minimize the effect of a single failure, e.g. by the use of multiple amplifiers with segregated cable routes. 

• The public address systems should have at least two loops of flame retardant cable which should be sufficiently separated throughout their length and have two separate and independent amplifiers. 

• Each loudspeaker should be individually protected against short circuits.

• The public address system should be arranged to operate on the main source of electrical power, the emergency source of electrical power and transitional sources of electrical power.

• The space containing a control unit of the public address system is a control station as defined in SOLAS.

Cabling for PA and Alarm Systems:

• Cables and wiring serving internal communications or signals should, as far as practicable, be routed clear of galleys, laundries, machinery spaces of category A and their casings and other high fire risk areas unless serving those spaces.

• Where practicable, all such cables should be run in such a manner to preclude they're being rendered unserviceable by heating of the bulkheads that may be caused by a fire in an adjacent space.

• All areas of each fire zone should be served by at least two dedicated loops sufficiently separated throughout their length and supplied by independent amplifiers.

• Equipment associated with the public address systems should meet the requirements for vibration and electromagnetic interference. 

• Electrically powered systems should provide a minimum degree of ingress protection appropriate to the location.

Reference: 

1. IMO Publications & Documents - International Conventions - SOLAS - Chapter III - Life-saving appliances and arrangements.
2. IMO Publications & Documents - International Codes - LSA Code - Chapter VII - Other Life-Saving Appliances.
3. IMO Publications & Documents - Circular - Maritime Safety Committee - MSC/Circular.808.