An Emergency Voice Communication (EVC) system provides two-way communication between the emergency services, principally the fire service, and those people inside a building who need to be evacuated but are unable to immediately leave.
The reason for this could be because they are handicapped, suffering from an injury that impairs their movement, pregnant, or are in a building that requires a phased evacuation.
In the event of a fire, people in this position should know to make their way to an identified safe refuge area and it is here that an EVC system is expected to be located.
EVC System
An EVC System is a full duplex system that allows voice communication in either direction between a central control point and a number of other points called “outstations” located throughout a building or building complex.
The nature of the design of the outstations and the overall system is governed by stringent British Standards and guidelines and it is a part of the 5839 British Standard series that provides recommendations for the planning, design, installation, commissioning and maintenance of EVC systems in and around buildings and at sports, entertainment, and similar venues.
Recommendations for EVC Systems
The mains supply circuit(s) to all parts should be dedicated solely to that system
It is recommended that the mains supply circuit(s) to all parts of the EVC system except outstations should be dedicated solely to that system and should serve no other systems or equipment. It also recommends that the circuit(s) should be derived from a point in the building’s electrical distribution system close to the main isolating device for the building.
Regarding the positioning of outstations in buildings, it is recommended that they should be located where background noise is normally low, preferably not more than 40 dB(A).
Where there is a higher level of background noise in an emergency, the installation of an acoustic hood or structure around the outstation could be employed to reduce this to an acceptable level. It is also recommended that fire alarm sounders should not be located near to outstations.
The master station
The master station should have a telephone-style handset or microphone and loudspeaker for voice communication purposes, controls for making calls to, and receiving calls from, outstations, indicators to identify incoming calls, and fault and status indicators (BS5839 pt9: 2011 Master stations Section 2-12.1).
In accordance with BS5839 pt9: 2011 Section 11.5 k, EVC systems should not be dormant at any time, and outstations provided for use by people at refuges should be readily available at all times and should not be secured.
Under the Regulatory Reform Order (2005), deviations away from this should be logged and the liability for death or injury falls on the “competent person” making the judgment.
Types of design
There are essentially two types of design of outstation which are identified as “A” and “B” Types
There are essentially two types of design of outstation which are identified as “A” and “B” Types. Type A outstations use a telephone handset for communication and are identified as fire telephone/steward telephone. Type B outstations use a hands-free intercom unit, which are normally mounted on the wall with a single call button operation.
Type A outstations should be used for evacuation or fire fighting use and a Type B outstation should only be used where Type A outstations are impractical.
For disabled refuges where being operated by members of the public, for example, Type B outstations are generally used provided that the background noise is below 40dBA – fire alarm sounders in close proximity would be removed or changed to a beacon and noted as a variation on the fire certification.
Recommendation
It is recommended that a Type A outstation is used in most locations, otherwise, it may be necessary to consider acoustic hoods or two outstations in each location for compliance with the other associated standards and laws, including BS8300 and the Equality Act 2010.
The Type B outstation can offer a line out for an induction loop as an optional feature, although there is no requirement under any legislation to have an induction loop fitted.
Consequently, it is within the remit of the individual risk assessors of a building to determine whether this would be of benefit to the people using it. All wiring for Type A outstations and all network cables should be in enhanced fire-resistant cables. Type B outstations can be wired in standard-rated fire cables, except where there is an increased risk of exposure to fire in adjoining fire compartments.
A routine service
It is important to organize a routine service and maintenance contract
Once the EVC system is installed, it is important to organize a routine service and maintenance contract that can provide a Certificate of Compliance to BS5839 Part 9. As part of this contract each outstation should be operated and checked for clear speech and intelligibility.
A visual inspection should check that outstations are unobstructed and free from damage. Batteries and connections should be examined to ensure that they are in good serviceable condition.
All controls and visual indicators at the master station should be checked for correct operation and fault indicators should be checked by simulation of fault conditions.
For Refuge Areas
A Disabled Refuge is a relatively safe area within a building where mobility-impaired occupants can be placed during the evacuation, allowing building management and emergency services to safely assist these people from the building when stairwell crowding has eased.
Refuge areas can be enclosure places such as a compartment, lobby, corridor, or stairway where protection from fire and smoke is provided. Once a refuge has been identified it should be suitably signed and kept free from obstruction.
Identifying refuge areas
Where disabled people are unable to use stairways without assistance it will be necessary to identify refuge areas. Mobility impairment is defined as not being able to walk 200 meters continuously without aid, and includes arthritis sufferers, people with leg and back injuries, and women over six months pregnant.
In accordance with The Disabled Discrimination Act (DDA) 2004 any non–domestic building with more than one storey should provide a means of refuge for any person who cannot easily use fire escapes, lifts, and stairs during an emergency. The BS9999:2008 standards sets the criteria for refuge areas and indicates that an effective two-way communication system should be in place for these refuge areas.
