In the third of our series on technical fire safety issues, our resident 'Fire Doctor' David Brown discusses the new standard for visual alarm devices – EN 54-23.

Why is there a need for EN 54-23?
The British Standards Institution (BSI) introduced EN 54-23 in May 2010 to specify the conformance criteria for Visual Alarm Devices – or VADs as they are commonly referred to.

Before the introduction of this standard, there was no way of determining the effectiveness of a VAD. Different manufacturers would quote candelas, joules, or watts. This standard provides a common format so that the performance of the VAD can be proven and understood.

By ensuring that VADs meet certain standards of output, they will be more effective at alerting deaf and hard of hearing people to possible danger.

Although there are some very bright beacons currently available, none have been tested to the new standard and manufacturers have until March 2013 to introduce compliant products.

So, has EN 54-23 been introduced just to aid compliance with the Disability Discrimination Act (DDA)?
Primarily it has been introduced to “standardise” the rating and performance of VADs as mentioned above. While there has been no direct ‘on the record’ reference to it being developed specifically for this purpose, it would be reasonable to assume that the DDA [now mostly replaced by the Equalities Act] is a key driver, certainly within the UK.

Although much of the publicity about this standard has focused on its importance for deaf or hard of hearing people, it should be remembered that EN 54-23 compliance is also a requirement for areas of high ambient noise, such as factories, where people have to wear ear defenders to comply with health and safety legislation.

The risk assessment that needs to be taken under the Regulatory Reform (Fire Safety) Order (RRFSO) will ultimately determine whether VADs are required in a particular building.
 

I’ve heard that the new VADs will use so much power that I might have to install them on a separate loop. Is this true?
There’s no doubt that the new VADs will use more power but it is early days and there is a lot of research yet to be undertaken.

Obviously, having detectors and sounders on the same loop is preferable as it reduces installation costs and I would imagine this is what the industry will be aiming to do. If for whatever reason they can’t be installed on a single loop, VADs may have to be put on a conventional circuit. I am sure however, that different manufacturers will introduce innovative designs to overcome this issue.
 

How will EN 54-23 differ from the current system of rating a VAD using joules?
EN 54-23 specifies a volume of effectiveness whereas joules simply refers to the amount of energy that the strobe in the beacon can output.

It is very difficult to measure a flashing light and ascertain whether it has the correct intensity, as this requires specialised equipment. Manufacturers will have the VAD tested by the notified approval bodies, which will carry out all of the laboratory tests to indicate the area a VAD will cover and rate it accordingly.

Once compliant devices are available it will give installers an easier way to configure a system and will be particularly helpful from the point of view of spacing.
 

I also read recently that a VAD will need to have a greater output than two candelas. Is this correct?
No it is not. The standard specifies that for an “O” rated device, the output should be greater than one candela for 70% of the measurement points. In reality though, this is next to useless. For example a one candela flashing light source will only have an effective range of 1.6 metres, so will not even reach the floor. To further put it in context a VAD placed at 7.5 metres spacing (in line with smoke detectors) will have to have an output of 26 candelas. That is probably 10 times greater than existing ceiling or wall VADs from manufacturers.

One of the reasons for the output levels being determined as they have been is so that light can be reflected off objects, reducing the need for individuals to be in the direct line of sight of a VAD. This is based on research that has been carried out in America. Incidentally, the specified light output is the same as that specified by UL – 0.4 lumens per m2 or 0.4 Lux.
 

Are radio devices exempt from this standard?
No, they are not and this is another area of confusion. This mainly stems from the wording in the scope of the standard and there needs to be industry clarification on this issue.
 

Does EN 54-23 cover the same ground as LPS 1652 Code of Practice for Visual Alarm Devices used for Fire Warning?
EN 54-23 refers to the device itself, while LPS 1652, which is at draft stage at present, provides recommendations for the planning, design, installation, commissioning and maintenance of VADs in buildings other than single family dwellings.

They essentially work in harmony. LPS 1652 is based around the use of VADs compliant to EN 54-23 and refers to this in the spacing recommendations.

Within the LPS 1652 document correction factors are made for the ambient light at the installation, and whether the VAD will be directly or indirectly viewed during its operation. These factors can have a significant effect on the spacing

LPS 1652 does not recommend whether VADs should be installed, as this is the responsibility of the person undertaking the risk assessment. However, once ratified, it will provide valuable guidance on rating and spacing issues.

David Brown is product manager at Hochiki Europe. Topics to be covered in future Fire Doctor columns include: Digital v Analogue Technologies; Centralised v Decentralised Intelligence; and Aspirating Detection Technology. If you have any questions on these topics, email: editorial@info4fire.com