Alarm advice with cats in mind.

[PJO]

I think you mean "Double Knock"?!

Is it? I've never heard of it. The average magnetic contact has an operating gap in execss of 20mm. Newer ones will stretch to 80mm! That's some warped door!!! As for wind... I have never known wind to cause a door contact to operate. That is unless the door is blown open!

Door contacts are usually fitted in the door frame on the opening edge for ease of wiring but can also be mounted in the head of the frame approx 6 inches from the opening edge. As a general rule the door should open a maximum of approx 8 inches before the contact operates and the further from the opening edge the more the door needs to open. On bolt hinged doors the contact can also be fitted on the jamb edge.

Usine two detectors in parrallel is another idea but is messy. Dual-tec detectors do the job well.

With respect... glass breaks detectors are useless because the ultra-sonic sound they rely one (breaking glass) can be caused be many other natural sources. Fridge motors is a good example! I remember in the early 80's when these bacame popular. We installed hundreds of them in schools, shops and the like. Then the kids discovered that if they through milk bottles outside the window the bloody alarm would activate! No, forget break glass detectors.

As for window foil. It's outdated by many other forms of setection such as curtain PIR's etc. You can't even buy the proper foil and blocks these days.

Smoke bombs eh?! Corr!

Burglar identifying paints?? Don't think so. You've been watching too much

007!

Maybe you mean ID spraying? In which case, as we're on a DIY group, I don't think it's worth mentioning as the minimum cost of registration and instalation is around £5k!

A/T wiring has been standard since the 60's and is an absolute must. It's not just there to warn of attack but also to give alert to damaged wiring etc.

But it is if it does the job. In my time I have installed thousands of 3 PIR systems with panels that have no more than a single knoxk circuit. They rarely false alarms and always activated on intrusion.

I'm not having a pop at you NT. I'm just using your post as an example of how wrong terminology and poor advice can cause more confusion that it's worth. We're talking security here and it's not good to give outdated advice and non-suitable idea's.

[PJO]

Yes, a good idea and there is always the option of security film too.

Problem is that if they want to get in a simple large jemmy bar will not only remove the glass but the whole frame too!

I've mentioned security film there but please be aware that for a proper result it's not a DIY job. Most first timers mess it up and end up with dull patches and creases all over the gaff.

[Dave Plowman]

Well, just about everything fails eventually.

Hmm. Ever heard of packing something square? Of course judging by most of the pro burglar alarm installations I've seen in houses, care and neatness was the last of the priorities. I hope you're different, although given the cost in time of concealing all cables and switches etc, I doubt it.

They all still work, so no, I've not done a physical check.

Most burglars aren't pros. They are druggies etc looking for a quick buck. A pro burglar would pick somewhere with richer pickings than my modest pad.

I'd love to see the lock which makes the surrounding frame etc stronger. No locks will stop a determined attack on a wood sash window. I'm surprised at you if you're in the trade.

To the best of my knowledge, non of the nearby systems that constantly give false alarms have pressure pads. To install them *properly* is too much work - as is fitting window and door switches *properly*.

I'm afraid you're coming across as so many other pros - you recommend as gospel that which is easy to install.

[Dave Plowman]

The standard magnetic switch has to move a fair old way to trigger. It would be some warping or wind movement that would cause a *properly* fitted one to trigger.

That was my thinking behind using door and window switches, pressure pads, and PIRs. I don't think any one solution is the perfect one.

[PJO]

Doubt what you like but I can assure you than I have NEVER shown a cable on ANY installation and that includes not only houses but industrial buildings, shops, ships (yes, ships!) and even the odd Royal Palace.

Ah, right. So, your waiting for the alarm to give problems and annoy your neigbours jost like the professionaly installed systems which you mentioned earlier?! Ever hears of preventative maintenance. It'll also be interesting to hear what you do when your pads do pack up because (and I may be wrong) I don't think you can buy them anymore! Most of the major alarm wholesalers I know stopped stocking them in the early 90's. I think that says a lot?!!

You'd be surprised.

You simply bolt the two halves of the sash together and they then cannot be opened. Forced out yes but not opened.

As for securing the frame. Yes I agree - it's difficult. In th epast I have used ally angle which the bead fits over to hide it. Very effective indeedie!

It's nothing to do with fitting the contacts (or other devices) properly. It's all about care of installation. Soldering joints, avoiding EM interference, using proper clips - not a staple gun, etc.

You're totally wrong. What I advise is the best options. I have had very few "easy fits" and have never been in the "cheap brigade". I have never installed a system in a house - even a very small house - for less than £500. Why? because I did it properly. I never had systems which troubled and many systems I installed over 20 years ago are still working just fine having only had the odd battery or sounder replaced. As a general rule I was only ever called out to systems when something needed altering such as customers replacing doors etc.

So please, don't paste me up with th evast majority of pricks who call themselves alarm installers. I'm one of the few remaining good boys!

[Owain]

"Dave Plowman" wrote | PJO wrote: | > As for "switches" on doors and windows... a complete and utter waste | > of time and money. Contacts on windows are all well and good providing | > the burglar opens the window! Most of the time they smash through | > leaving the opening frame in place and therefore not causing an alarm. | I've been burgled once and had a couple of attempts (before the alarm was | fitted). Each time they levered open - or attempted to - a sash window. | Most casual burglars don't want to crawl through broken glass - would you? | Same with my neighbours that have been burgled.

I think many intruders will try to spring a frame open as it makes less noise than smashing a window - and this country has a significantly high level of burglaries whilst the occupants are at home.

Window contacts can detect an attempted intrusion rather than waiting until the intruder has entered the property, which has got to be reassuring.

Also, perimeter protection means that occupants can wander around the house at night with the alarm (part) set - especially important with bungalows (although a PIR in the loft can be useful in modern bungalows with tile roofs which are vulnerable).

Owain

[PoP]

I remember when my daughter was born 16 years ago I bought some security film on a roll in Mothercare, and applied it to a low-level window in our rear patio door - which was plain glass.

You are absolutely right about getting creases - even though I thought I was taking care! I should have taken a bit more time.

PoP

Sending email to my published email address isn't guaranteed to reach me.

[Dave Plowman]

That's excellent to hear. But I think you'd agree the vast majority of domestic installations fall far short of this? To fit the switch to my front door involved chasing in the cable and re-decorating - I really can't see many installers doing this, somehow, apart from perhaps on a new build.

Well, once in 10 years will still be better than several times a year.

FWIW, they're still listed by TLC.

If they did go wrong, it would be a simple matter (for me) to isolate them since they work via a home made relay interface.

I'm talking about probabilities, not exceptions.

That's how mine was opened - forced until the sash gave way. Bolting the two sashes together will weaken the top/bottom rail. If you really want to fix them closed, use screws through the sides and bottom or top into the frame - much stronger. Do this beneath the putty so they don't show.

Looking at the front doors and frames they fit in 'problem' council estates, etc, it would need more than a bit of angle ally to stop a determined thief. Plate steel seems more like it. But at the end of the day, given time and not being overlooked, you can get through near anything.

Could well be. But like everything else, speed and cost of installation seems to be the prime consideration, rather than making a decent job. Same as kitchen fitters etc.

I didn't for one moment *actually* think otherwise. ;-) But I'd say you're in the minority in your trade.

I'm certainly interested in what you say, as being a self installed system it would be easy for me to alter it to the latest standards.

[PJO]

Many do do it properly. I could have fitted your front door contact in the proper place WITHOUT chasing or re-decorating! That's doing it right. Your way probably took 10 times longer than my way too. Perhaps it's called training?!!

But it won't just be once will it?! It'll be lots of times while you try and fathom what it is causing the problem. OR are they all on independant zones??!!

WHHYT too though? And FFGHT. AND what's TLC?

Oh, right. A home made relay interface eh? That's secure innit?! Can you bake little butterfly cakes too?

And as a security advisor I'm talking about both.

When I worked on the security team for a major alarm company we used brass, concrete, steel, ally, titanium plate, etc. The risk was high and money no object though. Not like your average semi! Good home security using proper pucker equipment needn't cost the earth. The problem with most people, especially DIYers is that they just hate spending money on it. Hence cheap crap equipment sold by B&Q, Wickes, etc. sells plenty. Once major retail chain is still selling an alarm system with a plug in PSU. Another uses PP3 batteries for the backup. The problem is the great buying public. They're gullible an ill informed most of the time.

Why are you digressing so much? From what you have posted in this thread I can judge that you have made a pig awful job of designeing and installing your alarm system. No cables on show maybe, but the system is crap and you took too long messing about instead of just buying proper dedicated equipment and doing the job like a pro would. Or do you think the way you did it, with your home made relay interface, chasing and re-decoration is better?

Agreed. And it's no longer my trade.

Disagree. The latest EC standards for intruder alarms are exeptionally stringent. I can't say I agree with them and in fact I absolutely disagree with most of the new regs but that the way it is. Trust me, your home made relay interface and pressure pads don't even scratch the surface!

[PJO]

ONLY IF THE WINDOW IS OPENED!!!!!! If the frame is forced from the wall - no alarm! If the glass is broken and access made through the space - no alarm!

Yes, but the perimeter protection needs to be proper - not contacts. With contacts, for example, you can't have a window open for ventilation while the alarm is set. With inertias you can.

As for a PIR in the loft... yes, great idea - until summer when the loft gets hot and the PIR goes asleep! Oh dear, you didn't know about that did you??!!

[PJO]

Yes, it's a bitch and a half to fit properly.

[N. Thornton]

No worries :) If I'm wrong keep saying, and together we all learn.

That sounds different to the ones I've had experience with. They didnt have anything like 20mm to play with, and proved to be useless. They were affected by warp, wind, you name it. The ones that were decommissioned were magnets and reed relays. But if things have moved on, good, I gather they have.

Yes, this is another way of implementing the above, rather than implementing it at the control panel. Either way, 2 detection events by 2 different technologies are needed to avoid false alarms.

Youre describing early ones, which were problematic as you say. Things have moved on. All detectors have false trigger modes, these included. What you describe is the result of using low tech detectors and using a control panel that (wrongly) triggers from just one detection event. If you use them with another detector type, with 2 events being required for system trigger, you have a sound system. Or just use a modern glass break detector with proper discrimination.

Here we go:

"Older models were plagued by false alarms. This is because they did very little filtering and even much less audio processing to tell the difference between a valid sound and one that is normal to the environment. More recent designs now use microprocessors to digitize and process the audio sounds picked up in an environment. This enables them to discern the difference between the sound of a window breaking and that of a broken drinking glass."

This explains why modern ones are reliable and effective, and incorporate the tech you mentioned above:

As for window foil. It's outdated by many other forms of setection such as

It is around, just not popular. Google. Also, copper adhesive foil used in lead window making can be used effectively.

Handbook of Loss Prevention and Crime Prevention, Butterworth-Heinemann:

"In the past, foil tape was the most common way that security installers electronically secured window glass. Although it is not as common today, foil tape is still used by alarm installers who are skilled enough to work with it. In fact, many of them swear that it works better than any of the electronic devices--called glass-break detectors--used by other installers. "Metallic foil...is widely used to detect glass breakage in show windows, doors, and transoms. When the glass cracks and breaks the foil, it interrupts the low voltage electrical circuit and activates the alarm"

"The presence of foil tape on windows is an automatic sign that a burglar alarm system is employed on the premises. Most burglars would rather not break into a facility that has one."

Yup, they work by disorientating the burglar, and making them realise they are out of control of the situation. If you have a large valuable premises, using these by entrances halls stops many burglaries in their tracks.

The disorientation makes it take a long time to simply get back out of the building, thus improving odds of arrest, as well as being visible to passers by.

I did say if you had money to spend: this is not really your usual 2 up 2 down kit :)

£7:49.

There are also more technological ones available, which stain the skin indelibly, but the simple cheap option above is suited to diy use on drain pipes etc. They both deter and help catch afterwards.

My own experience with PIRs makes that hard to imagine. Perhaps either youre using PIRs that require 2 events to trigger, or use dual technology, or else PIRs have suddenly come a long way?

Over to you.

Regards, NT

[PJO]

No, basically they're still the same. A reed and a magnet. The operating gap should always be 20mm minimum. Perhaps some cheaper makes have an insufficient magnet though.

Some contacts have moved on a little though. ID contacts incorporate a chip which is directly affected my a magnet. These are usually in 7/16 inch bullet type contacts and are only suitable for use on ID systems.

Oh and we should all be using ID these days because not only is it much more secure but it's also very easy and cheap to intall and offers much more flexibility that conventional systems.

detector can false but these breakglass detectors are more prone. Put it this way... they are almosy outlawed in the new ACPO (Association of Chief Police Officers) policy.

No, still can't agree. My experience says different and I'd avoid them like th eplague.

No, what's still around is self adhesive alluminium crap. Proper window foil was lead and not self adhesive.

And what year was that written? 1904?! Trust me, no alarm company uses foil these days. OK odd job yes but it's just not used as a general rule. It's not been in the course syllabus for many years.

And again, when was that writtin? 1906?! It's true of the 70's but today all premises are secured and foil is long ceased to be used.

I was actually being sarcastic. Smoke Bombs as you call them are actually Smoke Generators. They produce smoke by heating glycol - like a disco smoke machine - same stuff. They are on standby when the alarm is set and activate the pump when the alarm activates. The most well known system is Smoke Cloak but these days theyre are "copies". Smoke Cloak was first shown around 1887.

Yes, they're bloody effective but again, we're on a DIY group here and so it's unlikely to be of any use. I do though admit to having one installed in my workshop/garage at home. Expect to pay upwards of £400 for one, maybe more for a decent one. Refills of glycol are around £20 and you'll need plenty cos you'll show it off to all your mates!

While on the subject... smoke generators are not up to much after a door or window is left open as the smoke depletes very quickly. Better machines iave a sensor which, when the smoke thins out, re-activated the machine to top up the smoke. For this reason your suggestion of installing them in entrance halls is a no-no. They're mainly used to secure area's "not yet intruded" thus making entrance to that area very difficult. Computer rooms in office buildings are a good example.

hands black. Does that mean that when I next do an oil change on my car and end up with black hands I'd better avoid being seen in public?!

Deter and prevent yes. Help catch - no. Not at all. A simple wip with a rag and it's gone.

How about when you have someone in your house you don't really know? Decorator, gas man, daughters boyfriend. Wouldn't you like to know when and if the PIR's, for example, had had their lids removed?! Or what about when you nic a cable doing something. Wouldn't you like to know there and then instead of waiting till you try and set the alarm and then have to wonder where the cut may be?! How about British Standards which have stipulated A/T wiring since 1980 when the standard was first introduced!

Or how about someone gettign a ladder up to your bell box, removing the lid and cuting th ebell feed. Wouldn't it be nice to know?!

See above

In the last 15 years alarm panels and detectors have moved on so much that they are now very good. Ducl-tec, pulse count, double knock and ID have all helped.

Even so, like I said I have installed systems before that which have been nothing but well behaved. It's down to good engineering practice, common sense and not buying cheap. In 1990 you could buy a UK made PIR for £6. £4.50 if you bought 50 or more. I bought none, instead choosing to stick to the old faithful ones that had been used for years previous. The company who made the cheap £4.50 PIR's went pop after just two years! Says it all. Buy cheap and not only will you have to buy twice but you'll have loads of grief too.

[Andy Hall]

As a matter of interest, how would you do that? .andy

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[PJO]

With a little skill and care, the proper tools and most importantly... experience.

[BigWallop]

I think your both correct in the things you say, but an intruder is going to attack if they want to, no matter how good your alarm system is. If you have something in your house they want, they'll come in and try to get it. If your want to put the most determined burglar off attacking your property, then empty it of all the contents and leave the doors and windows open. That way they think there's nothing there to steal.

A proper security system stops the would be opportunist from thinking of attacking your property long before they even get to boundary. This is done mostly by psychology in the use of signs and visible warning systems. Lighting and sound puts most chancers off when they encroach into the perimeter of your land, so they don't want to come in any further and increase the chance of being caught or injured.

So you can put as much equipment in the house as you like, and wire it all together properly or otherwise, and I still bet I can stop your property from ever being a target in the first place with use of simple screw on devices that look nasty to any would be intruder.

[BigWallop]

I've got to agree that glass-break detectors are one of the worst sources of false alarm on any system that employs them. Just running an aluminium can along a piece of glass in the property can cause them to activate. We hate using them and try not to unless they're fitted in an office on the fortieth floor of the block, but even these have sometimes been activated by pigeons.

[BigWallop]

The perfect solution is to prevent, as far as possible, your property from becoming a target in the first place.

[BigWallop]

External or internal metal bars are cheaper, and are more of a deterrent because they can be seen from further away.

[Andy Hall]

I realise that, but I was rather hoping that you might enlarge on exactly how, to the benefit of the assembled gathering....

Low voltage wiring for the purposes of alarms, networking and the like is increasingly popular and I am sure that the group would welcome information on ways to install cables etc. with minimum visual impact or the need to redecorate.

.andy

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