Best tool in the box

As the days go by I am fielding more and more enquiries about the Old vs the New standards, and I don't have all the answers. I am pretty sure no one else has either, so there will, obviously, be many and varied interpretations of the new European standards and it will be left to the inspectors to pick up the pieces.

As usual, those of us with our feet on good British soil are being told by those with their heads in the European clouds what we are going to do and when. So, remember that we are having to administer an incomplete standard – but please don't shoot the messenger.

Most installers – as the saying goes – "can't make ash nor coke of it" and they want some help, so the inspectors, and my fellow writers in Security Installer and I, will try where we can.

This week I have been tackled about readings, or – to be more accurate – the record of system checks. I have lived with readings for the whole of my 30 year career in this industry and I find it hard to picture a standard that does not include them – but EN 50131 does not.

They may be included in some of the yet-to-be published sections but that remains to be seen. So the next question is, do we carry on with them or do we throw out 30 years of good practice?

Readings ... not a work of fiction

To answer that we have to look at why we need them and what benefits do the readings bring us?

This comes down to trouble shooting.

We need the readings to confirm that we have done a good job, and as a reference point for the future. They are not to be filled in from the top of your imagination on the way home in the van.

In BS 4737 we are asked for a resistance reading on the detection cables. This is to verify the integrity of the cables before we commission the system. Unfortunately there are far too many "engineers" out there that don't understand the readings, so here goes ...

The average 100m roll of cable has a resistance of around 8-10 ohms per looped pair so it takes very little brain power to work out that 10m of cable to a door contact will read about 1 ohms. If we see a reading of 10-15 ohms then it is pretty obvious that something is wrong even if the panel will accept the circuit as well within tolerance.

A good engineer will measure and go troubleshooting, a poor engineer will walk away and ignore it, a dishonest engineer will invent a reading. Resistance readings are a very useful tool – are we to throw away the best tool in our box just because it is not in the new standard? I certainly hope not.

BS 4737 also asks for a reading of the voltage (where appropriate) at the device end of the cable. This is to ensure that there is enough power to run the device with stability. It also acts as a pointer to bad or damaged cables and connections, all of which can increase the impedance and reduce the voltage.

PIR gets unfairly blamed again

Who but an idiot will walk away without checking that the device they have hung on the end of the line is not gasping for more power and will suffer an occasional drop out? Yet another of these mysterious alarm activations that are blamed on the PIR.

It is probably even more important with the current readings. If an electronic device goes faulty a change in the current consumed is often the first and easiest sign to look for, so why throw that little tool away? Having said that, there are far too many installers that take BS 4737 at its word instead of its intent and only measure the total current used by the system instead of measuring each individual device. But it is so easy to do. Twist the positive wires together and connect, then measure each negative wire to the negative supply terminal in turn. The longest job will be waiting the 10-15 seconds it takes each device to settle after the application of power.

Let's face it, if you have the right voltage, the right current and a suitable resistance reading then you have probably got a good sound device and any problems you are having are environmental not electrical.

Readings on batteries is another very useful tool that is almost totally ignored by the installer. Batteries and their relationship with the charging circuit is an inexact science to us mere mortals at the best of times but that is no reason to just ignore it – even the layman can, with a little understanding, make some informed judgements when the time comes.

It's all a matter of balance; if we have the right charging voltage and a reasonable charging current then the chances are that the battery is sound. Ideally the charge rate should be between 13.5v and 13.8v – with the battery connected. Higher voltages could possibly ram-charge the battery and shorten its life. Lower voltages may mean the battery will never fully charge and that in turn may mean that the system will not run for the required time during a mains failure.

As a rough guide, the current going in at the normal charge voltage will be very low, only half a milliamp or a couple of milliamps at most. When the current starts to rise up to 10-15mA then that could be the first sign that your battery is starting to wear out. Keep an eye on it. Coming back to the original plot – are we going to throw this useful tool away as well? I for one would be loath to see it go.

The requirements of BS 4737 are a little open handed when it comes to readings, but the idea was to give guidelines for good working practice not to give the inspectors a big stick to hit you with. I have always been of the opinion that BS 4737 was written to give the basic guidelines and that the installer would extend and amplify those guidelines as the system required.

Are they assuming too much?

Could it be that the new Euro-standard assumes that the installer knows the right readings for the job in hand and should not need to be told these things, so they have been left out? Who knows? It is a distinct possibility.

One thing I am certain of – if an installer (commissioner) fails to take the proper readings then he is failing his duty to his employer, his fellow installers/service engineers and to the customer. Even worse, if he fails to understand the readings or the reason why they are to be taken then in my book he is taking money under false pretenses every time he opens his wage packet.

The other problem that cropped up recently is the standard for wire free systems. Whilst the new Euro-Standard talks of Grades 1, 2, 3 and 4 for levels of security, I have yet to find any reference that relates to the classes of wire free system that we currently use.

From the inspectorate level we will only accept Class 3 and upwards. The police will only accept Class 6. There really should be some way to tie the two together, or we could end up with all manner of cheapo stuff masquerading as Euro-compliant. Bearing in mind that my knowledge of radio equipment could be written on the back of a postage stamp, here is the situation as I see it.

The integrity of wire free kit depends on two things – the time it takes a control panel to realise that a detector has gone missing, and the levels of encryption within the signals. Without some form of tie-in then we could find a Euro-Grade 4 system using technology that could be breached by a ten year old boy with a crystal set. The good stuff, with encryption codes as long as your arm and polling times that would flag up a failed (or stolen) detector within minutes instead of days, may well be pushed out in favour of cheapo technology when the great god Money raises it's ugly head.

We need some guidelines. But who is responsibility is that? There is a very distinct gap in the standard here that we need to fill. Once again, it may well be that when the rest of the EN 50131 suite is published these gaps may be filled, but at this moment we are launching the good ship 50131 without the lifeboats. The only advice I can give is stick to the "known good" like FM Electronics or Scantronic or others of that quality.

Do not skimp on the price. You get what you pay for so avoid anything you can buy in the big DIY sheds. Ashley Thomas of FM has written on the subject of wirefree in this issue of Security Installer (see page 39) so read his words. It’s his trade and he’s the expert.

In a different bracket

Another problem that rears its head on too many occasions is that of the brackets that come free with PIRs. The PIR may be compliant with both the old and the new standards, BUT if the bracket can be adjusted without causing a tamper alarm then it is not acceptable. If you are in any doubt, fix the PIR direct to the wall and throw the bracket in the bin.

So, do the manufacturers tell us that the brackets do not comply or do they assume that we, the installers, should know the standard and leave that info out of the accompanying literature? True, the installer should know the standard, but I think there is a responsibility on the part of the manufacturer to make sure that the installer knows. After all, we buy the PIRs in good faith and we have a tendency to accept the free bracket in good faith.

As I see it, there is too much hanging on the installer's knowledge and the installer's integrity. Could it be that the new standards assume that we will all, as a collective trade, see a need to take readings and distinguish what bits do or do not comply with which standard ... or will we all follow like sheep and do exactly what is written in the standard and no more?

In any trade or walk of life, if the interpretation of rules or standards is left to the man at ground floor level the diversity of that interpretation will be unbelievably wide.

On nodding terms

I pride myself on my sense of humour. but there are things that I consider to be, for want of a better word, naff ... one of them being nodding dogs in the backs of cars.

However, one such nodding dog gave me a laugh whilst I was in Hull a couple of weeks ago. This large nodding dog was in the back of a tradesman’s van. Someone had stuck a king sized cigarette in its mouth ... It reminded me of so many people I know who also can’t do anything without dangling a fag in their mouths.

Mike Lynskey is a former proprietor and independent inspector of alarm systems. He is now network manager with the NSI. The personal views expressed should not be taken as the opinions of the NSI. Email Mike on: mike.lynskey@virgin.net