Incident Report

Subject:                     Best of both worlds? EN54 products in NFPA 72 installations

Date of Email report:   Fri 24/09/2010

Report Detail:

The global fire detection and alarm market seems to be dividing into two spheres of influence: UL/ANSI equipment installed to NFPA 72 and
EN54/ISO 7240 products installed to country standards. But as Robert Dudley explains, EN54 products can be compatible – often with
only small modifications – with the requirements of NFPA 72 installations.
For many years the world of fire detection and alarm systems has been strongly influenced by product standards and installation codes. Over time, the market for these products has divided into two sectors; one dominated by products tested to UL/ANSI standards and installed to the requirements of the US National Fire Alarm Code NFPA 72, and the other by EN54/ISO 7240 compliant products installed using country specific codes. As the degree of polarisation within the global fire detection product market has increased, the opportunity for cross over between these two highly regulated sectors has diminished. Within some countries, there has been an increased tendency for consultants to specify that automatic fire detection and alarm systems must comply with NFPA 72. These factors have given rise to the view that equipment designed to meet the European EN54 Fire detection and fire alarm systems standard cannot be used within an installation designed to NFPA 72.
The view within LPCB (part of BRE Global) was that this perception was incorrect and steps were taken to challenge this. C. S. Todd & Associates were commissioned to carry out a detailed study of the requirements for products set out within the NFPA 72 code and the equivalent European EN54 standard to identify areas where equipment is compatible.
The report delivered to LPCB was reviewed and subsequently added to after discussing the objectives of the work with the U.S. National Fire Protection Association and the British Standards Institution. The finished document is available as a free download from the Red Book Live website, www.redbooklive.com.

The Study

Ten categories of fire detection product are assessed within the report, these are summarised below:
 

The assessment process focussed on comparing the technical requirements for the equipment and not on how the product is installed. For each of the ten product categories the relevant sub-clause in NFPA 72 that sets out the design and functionality requirements was tabulated against the corresponding requirements in EN54. Any differences between the two sets of requirements were then tabulated for each product.

Equipment such as municipal signalling boxes, which are covered within the NFPA 72 code, was excluded from the study because they are specific to the US and not generally used in other countries. A municipal box is accessible to the public on the streets of US towns and cities and is used to summon the fire brigade to a fire. Should the need arise to include one in an installation, its functionality can be mimicked using an EN54 compliant manual call point or input-output unit.

Key Findings
It is not intended within this article to detail sub-clause by sub-clause the findings presented in the report by C. S. Todd & Associates during their assessment of equipment compatibility – these can found in the report itself. Some of the main conclusions from the assessment, however, are summarised below.

General Comments

• NFPA 72 does not restrict the designer to only using products that are tested and listed to US standards; this is confirmed by sub-clause 1.5.1
• NFPA 72 does not specify that fire alarm system components need to be covered by specific standards, such as ANSI/UL 268, 521 or 864, this is confirmed in F.2.
  
• The Code does require that equipment used in the design and installation of the fire detection and alarm system is listed, this is confirmed by sub-clause 4.3.1.
  

Control Panels
EN54-2 compliant control and indicating equipment does not fully meet the requirements of NFPA 72, the technical issues to be addressed are listed below.

• Distinction between “fire” and “fault” audible warning signals is required at the control and indicating equipment (CIE).
  
• If a pulsing audible “fault” indication is used, each “on” period should be longer than ½ second.
  
• Silencing of audible “fault” indication should effectively be only possible at EN54-2 level 2 or a higher level.
  
• Full equipment function is required at 49°C and 85% RH.
  
• A fault on a sounder circuit is required not to affect operation of any other sounder circuit.
  
• A CIE is required to have at least one auxiliary output monitored for faults.
  
• No terminal for incoming and outgoing wires is to allow a single conductor to be looped around it.
  

Sounders
A sounder must be capable of outputting a signal that gives a pulse pattern compliant with the requirements of ISO 8201.
Certain marking and data requirements need to be addressed.

Power Supply Equipment
Actual response times for indication of the fault conditions must be declared by the power supply’s manufacturer to be less than 200 seconds.

Heat Detectors
NFPA 72 requires that heat detectors are marked with a colour code that denotes its classification.
The exception is a heat detector where the alarm threshold is field adjustable; these must be marked with the temperature range.
It should be possible to calculate the Response Time Index, if required, from the manufacturer’s data.

Smoke Detectors
Smoke detectors shall be marked with their nominal production sensitivity and tolerance (percent per foot obscuration).
Smoke detectors that have provision for field adjustment of sensitivity shall have an adjustment range of not less than 0.6 percent per foot obscuration.
If the means of adjustment of sensitivity is on the detector, a method shall be provided to restore the detector to its factory calibration.

Flame Detectors
Provision of specific items of technical data by the manufacturer

Manual Call Points
There appears to be no requirement precluding the use of manual call points.

Beam Detectors
The manufacturer must specify and declare that an abrupt interruption of the beam will cause a fault signal and not a fire signal to be emitted.

Short Circuit Isolators
There appears to be no requirement precluding the use of short circuit isolators.

Input/Output Devices
There appears to be no requirement precluding the use of input/output devices.

Future Developments
The findings from the study are just the beginning; the development of the Loss Prevention Standard, LPS 1281, and scheme document will be completed so that manufacturers can have variants of their EN54 certificated products assessed against the product requirements of NFPA 72. Manufacturers with an LPCB listed product could modify it to meet the NFPA 72 requirements and submit this variant for approval. LPCB scheme engineers would assess the variant against the requirements set out in the new scheme document. Successful products would be issued with an LPCB certificate and listed in the Red Book as meeting the product requirements of NFPA 72.

Benefits for Industry
A scheme of this type will help manufacturers enter new market places they may have thought were closed to them. Offering a listed product variant should be a low cost, low risk option for the majority of manufacturers promoting their products in NFPA 72 markets. This scheme will support manufacturers who want to access tenders issued by consultants in the Middle East, India, South America and various parts of South East Asia. The scheme will be supported by LPCB staff visiting these regions to promote the scheme, which together with the power of the LPCB brand should gain the support of local regulators.

Dr Robert Dudley is director, electronic research at LPCB.
Read the full report: US National Fire Alarm Code NFPA 72 and European Standards in the EN54 Series - Assessment of Compatibility

Additional Documentation:

NFPA72 and EN54