NSI interpretation on detectors is wrong

  As your readers will know, the NSI has been holding out the Optex Sequad detector does not comply with DD243, and has written to some of their registered installers in tones that are, to say the least, bullying, anti-competitive and stifling of innovation. It's like a reincarnation of the very worst interpretation excesses that unfortunately became synonymous with NACOSS.

I am pleased to find that my views coincide with many installers in the NSI, but the NSI having taken a position, seem to find it hard to climb down off the proverbial high horse. Well, I think they should and I am sure from calls made to me that I am not alone in that view.

  Strangely, the BSIA, that association with 108 of the 2,000 plus installers has been lined up with the NSI on the issue, which concerns clause 5.4.2 of DD243 and relates to the spatial separation of overlapping movement detectors.

The NSI interpret DD243 to mean that all movement detectors should be located some distance apart. They originally based this interpretation on research said to have been carried out by Building Research Establishment (BRE), even though this only related to overlapping detectors, and they have known for some time it is not relevant to non-overlapping detectors.

Thus, the decision by the NSI to issue deviations against the Optex Sequad detector was, and is, entirely wrong.

  I am not aware that the NSI has any registered competence regarding component certification or has an establishment of technical expertise necessary to issue 'deviations' on any detectors.

NSI should know better than anyone that DD243 is a code of practice and is not a 'product specification'.

I see no justification for any statements or inferences made or sent to approved installers holding out that the Optex Sequad detector is a non-conforming product, nor do I see any reason why certificates of compliance for installations fitted with this particular detector should not be accepted by the NSI.

Naturally, any installers who found themselves disadvantaged by the actions or advice of the NSI might well feel themselves aggrieved, but then that is a matter for them.

My concern here is that the NSI has been badly served by the advice it has apparently relied on and that coincidentally the action of issuing deviations wrongfully is commercially partial.

I prefer to believe that your readers would be very concerned if this view of mine coincides with theirs. DD243 confirms this view of mine because it sets out a list of movement detectors that do, and do not, comply. The reality is that NSI cannot find that the Optex Sequad detector doesn't comply simply because it does.
Mike Cahalane Security Consultant

Tom Mullarkey of the NSI replies ...
Thank you for a chance to comment on Mike Cahalane's letter. Although Mike's arguments are quite technical (and can be defeated with stronger technical counter-arguments), the issue itself is rather simpler. There are just two key points:
Firstly, the imperative thrust of DD243 (and Confirmation Technology generally) is to reduce false alarms. We need to do this because most experts agree that the industry is in the 'last-chance saloon' with police response.

To put some scale onto this, before DD243, some 200,000 false alarms were generated annually by faulting PIRs. In the future, our collective aim within the responsible sectors of the industry is to get this down to a substantially lower level. We are therefore looking for revolutionary new technology to assist in this process, rather than resisting it, as Mike suggests.

Secondly, this particular technology (two movement detectors in a single housing or TMDs), is likely to increase false alarms. We can predict this from experience of established PIR technology. There are many foreseeable environmental situations which are likely to cause a false alarm with this technology, such as draughts of rising hot air, gradients in temperature near windows and the effects of sunlight or a bright light source. Anecdotally, some companies have even carried out their own in-house trials on TMDs and found these effects to trigger false alarms. Manufacturers (other than the one Mike quotes) have also told us that in their experience, co-locating two PIRs will increase false alarms and it should be noted that rather than being 'some distance apart', the oft-criticised wording given in DD243, this technology is actually 'as close as two PIRs can get'.

The DD also specifically demands spatial separation to minimise the risk of false alarms, a clause rooted in the experience of its authors. Finally on this point, it is inevitable and incontrovertible that were TMDs to become established, some faulting PIRs, currently generating hundreds of thousands of false alerts per year, would be replaced by faulting TMDs, certainly generating significant numbers of false alarms.

So we have a situation in which the thrust of false alarm reduction, meets a technology which is likely to increase false alarms. It is our view in NSI that no industry organisation (or individual for that matter) has the authority to take a deliberate decision which would have the effect of increasing the call on police time or public funds. Only the police can make such a judgement and in the absence of that judgement (unsurprising in our view), it is the duty of the responsible to err on the side of caution.

To put this matter to rest, along with the other responsible sectors of the security and insurance industries, we are recommending an early objective false alarm performance test of TMDs (a test which can be applied to the example from this particular manufacturer or to other examples from other manufacturers as well). If this technology performs as perfectly as Mike is betting his reputation on, then we will of course be pleased to accept it in the cause of false alarm reduction. But if it does not, then its uses will have to be redirected to other, less exacting tasks. And perhaps in the meantime, the manufacturer in question could point his research team clearly at the actual problem, in the hope that none of us can be accused of stifling innovation..