Paving the way

When BS 5839 Part 6 was first introduced in 1995, it changed everything. Whether you were an installer, a specifier or a landlord. Here at last was a clear and detailed set of rules to be observed. The contents of BS 5839 Part 6 was quickly taken up and digested, and became simply the way the industry did things. To deviate was to invite real legal problems in the event of a fire and adequate 'Duty of Care' meant strict observance.

We've lived by those rules for ten years now, and they've served us well. No doubt they've saved lives. By their thoroughness, they've also helped cut costs incurred by any confusion and they've also set a simple best practice that anyone can follow.

In September 2004, BS 5839 Part 6 received its first revision. At first glance, those revisions seem quite minor.

This is deceptive and there is the danger that we will carry on essentially observing the pre-revision rules without fully understanding the requirements of the newly issued update. The publication of BS 5839-6: 2004 immediately superseded the 1995 legislation. The former publication is now withdrawn.

The purpose of this article, I need hardly state, is not to act as a substitute for reading the revised code in depth. However, it is intended to help highlight the major changes and their implications.

On reading BS 5839-6: 2004, you will see that each clause of the document is now split into two parts. Firstly, there is the commentary – in italics. This sets out the reasoning behind what at first sight may appear to be arbitrary recommendations. The recommendations are in normal type, so it is quite possible to simply refer to these alone. The intention is to make the document easier to use.

There are now extended recommendations with regard to new build properties. Essentially these are that all properties must have mains powered alarms with a back up supply – a Grade D system. Smoke alarms should be positioned in escape routes and heat alarms should be fitted in the kitchen and the principal habitable room. The definition of a principal habitable room is 'habitable room that is normally the most frequently used room for daytime living purposes'. This would normally be the living or dining room.

Slot headed screws not acceptable

Changes to Grades have also been made. There is essentially no change to Grade F, although a five year minimum battery life is recommended in tenanted properties, along with a recommendation that the battery can only be removable by the use of a special tool. A slot headed screwdriver is not considered as meeting this requirement as many articles can be used as an alternative.

Grade C systems now require a central control, rather than a level of control as previously. This implies that some form of panel is required and security systems are put forward as a possible means of meeting this requirement.

Risk Assessment receives brief coverage at the start, with reference to Annex A at the back of the document. It is worth noting the Commentary of Section 4.1: "It is considered that the level of fire risk in dwellings covered by this part of BS 5839 is unlikely ever to be sufficiently low to obviate the need for some form of fire detection and fire alarm system."

Grade C systems now require a central control … a panel is required and security systems are a possible means of meeting this requirement.

In terms of levels of coverage, LD1, LD2 and LD3 remain unchanged. However, the terminology has changed. The Code now refers to 'Category' of system instead of 'Type' of system. A small point – but, nevertheless, worth noting. For the first time, BS.5839 Part 6 now covers CO fire alarms and multi-sensor alarms. Heat alarms are given far more importance, as you will have noted from the New Build changes above, for example. Heat Alarms should always comply with BS 5446: Pt 2. A detailed commentary is given on false alarm control, which should be studied as this is probably the major reason that smoke alarms are disabled by the user. Among its recommendations are:

• Not using Ionisation-type alarms in escape routes
• The use of heat alarms where nuisance alarms could be a problem – only in areas other than escape routes
• A high level of maintenance to reduce the incidence of false alarms
• No automatic connection to the Fire Brigade, because of the high level of false alarms generated in the home.

Perhaps most importantly of all, BS 5839-6: 2004 paves the way for the growth in wireless interconnect technology.

Although the previous version of the document didn't preclude the use of radio as a form of signalling, it called for a single final circuit, which essentially ruled out the benefits in many cases because alarms would still have to be physically interconnected for power purposes.

Now, because of the introduction of new 'wireless' or 'radio' interconnect systems, Clause 15.5 paragraph B says: "If smoke alarms and heat alarms are of a type that can be interconnected by wiring, all smoke and heat alarms should be connected on a single final circuit". This is clearly intended for hard-wired systems, as a note added to this recommendation states: "This recommendation does not apply if the form of interconnection is not capable of conducting current," e.g. if the means of interconnection comprises radio communication rather than wiring.

Pages 42-43 of the 2004 Code now set out the criteria for radio-linked systems. It is acknowledged now that Grades D-F systems may use radio interconnection. However, it warns about the potential drawbacks of battery-powered units being interconnected in such a way if there is a need to replace the batteries at regular intervals (by implication mains-powered radio-linked alarms do not have these drawbacks).

As is typical with the Code, it stresses the need to ensure that such a system meets the needs of the application.

The new version of the Code also goes out of its way to recognise that the old Code provisions might have previously technically precluded the use of wireless systems and overcomes this by pointing out that issues relating to power supplies, fault monitoring and integrity and performance may not be the same for hard-wired and radio inked systems. Special recommendations are also given to their use in Houses in Multiple Occupation.

BS 5839-6: 2004 is an important document, not least because it paves the way for new technologies that will change the way we design and install mains-powered alarm systems. It builds on the success of the original standard and if adhered to properly, ensures greater safety and even better practice in the industry.