Alarm Sensors

patrido

There seems to be lots of alarm knowledge here, so I'm hoping I'll get lots of advice

I'm planning for my alarm installation and I'd like to hear what people think about what sensors to use. The house is a largeish dormer bungalow, one bedroom downstairs.

A few new installations I've seen recently have just had magnetic contacts on the external doors, and PIRs in the downstairs living areas. Nothing on the windows.

Are PIRs enough?
Should I be putting shock sensors on the windows as well?
How should I protect bedrooms at night?
Can contacts be put on veluxes that will operate on the partially open (locked) position?

I don't live in a high risk area, and there's no way my wife is going to be stopped from opening a window at night to let some air in.

But on the other hand, I don't want to put in a really good alarm system, only to find someone has climbed in through my bedroom during the night and robbed my car keys, while I was asleep! No point having an alarm if that's going to happen!

I'm going wired, and don't really care how many wires have to go in. Cost isn't a major factor up to a point. I've even picked out a control panel that can be expanded up to 48 zones. What would y'all do?

delly

Not an alarm expert, but i'll give you my own personal opinion.

As regards downstairs i would get shock and contacts on all windows and doors. I wouldn't worry as much about upstairs, although i do have a shock/contact sensor on the one upstairs window which is over an extension. I also have a PIR sensor in the hall and landing which only activate on full set, i.e. when i'm out of the house.

There is a facility to attach my alarm unit to a phone line, which will call a preprogrammed number in the event of an activation, although i don't have it hooked up as of yet.

Lex Luthor

I personally don't feel PIR's are enough. Put them in, but don't rely on them.

I would put a shock & contact on all downstairs windows at the back & sides...a shock is enough for the front.

Shock also for the velux.

If your wife is deternmined to have a window open at night, then put this window on a separate zone, put a shock sensor on it and set the sensitivity of the zone a little higher than the rest. However a blind blowing about in the wind could trigger it.

The PIR's can go on their own zone, set them a part guard attribute, so at night when you put on partguard, the PIR's are off, the perimeter sensors are active and you can walk around inside.

Stoner

Just to add my bit, no offence to anyone

On the Velux windows, i would not put shock sensors on if I could back up a normal mag contact with a PIR. Each PIR has to be dedicated to its own zone under the regs. A shock sensor on a velux could cause alot of problems when it rains, if you have the velux and normal straight windows on the same zone you will have to turn down the shock level on all windows just to allow for the Velux, so if you have a few velux and you really think you need shock sensors then put them all the velux on the one zone and set it to min shock level.
What type of windows do you have? if your front windows have one large and one small wondow then you can put a mag/ shock combi on to allow the small window to be open at night but the large window on mag protection.
I agree with lex about PIRS, they are great but are only secondary alarms, if they work and pick someone up then it means they are in your house, where as the shock and mags will pick up someone earlier then they run off and you blame it on the wind and go back to bed. You could consider mad/shocks on all the windows and you could turn the mag element off at night but when your out at work you could put on a full arm

Lex Luthor

Good point Stoner about the shock on the Velux. I've no experience of Velux in any of my houses so that was a bit of info I'll take on board.

To be honest, I'm not really sure of the advantage of PIR's at all. If they're in, then there is something wrong somewhere else.

Like you say, if you have the option of 48 zones, then you have unlimited choices to wire up. Any odd balls like Velux might be a good idea to designate a separate zone for so you can play around with teh shock sensitivity that suits you.

Rew

Dont know much about alarms but I do know that there have been alot of car thefts in my area (and others, have a look at the motors section) where the theives removed the glass from a window got in and got the keys to the car and are gone without waking people sleeping upstairs or setting off the alarm. This makes me wonder how good the shock sensors are.

I come from a computer security backround and I reckon some of the principles apply, the main one being security in layers and expect some of the layers to fail.

Anyway like I said I know little about alarms so its just my 2c.

patrido

Thanks for all the replies.

Stoner wrote:

What type of windows do you have? if your front windows have one large and one small wondow then you can put a mag/ shock combi on to allow the small window to be open at night but the large window on mag protection.

Most of the windows have 2 large openings. I.e. window is 6ft wide, divided along the horizontal axis into 3 sections. the left and right panes open outwards and the middle one is fixed. I'm going to have lots of mags and lots of wiring to do

I presume a shock sensor will protect the whole frame/window regardless of the number of panes/openings? I.e. 1 per window as opposed to 1 per opening with mags?

Lex Luthor wrote:

Any odd balls like Velux might be a good idea to designate a separate zone for so you can play around with teh shock sensitivity that suits you.

that sounds like a good plan - i can fiddle with it until i get it right without affecting any other zones.

Rew wrote:

I come from a computer security backround and I reckon some of the principles apply, the main one being security in layers and expect some of the layers to fail.

That's a very good analogy! Now where did I put those plans for a moat full of crocodiles

Rew

I would go with trained monkeys with guns but licenceing is probalmatic in Ireland

murphaph

I recently fitted an Aritech system to my house. It's got contacts at all openings, shocks on the front & back doors only and 4 x PIRs backing those up. Now, I had 2 self contained shock sensor with built-in analysers. I have to say-they are nex to useless on PVC windows and highly effective on wooden door frames. I was told on a respected UK security installers website to expect this behaviour with PVC doors and windows and not to rely too heavily on shocks on those.

If your gonna use PIRs, try to get dual tech ones that have 2 different detection methods built in, both of which must trigger to cause an alarm. IR alone can be set ff by radiators and sun on floors etc. Usually dual techs combine IR detection and microwave detection. False alarms are almost unheard of with these because the they have no false alarm sources in common.

If you're getting a panel that expands to 48 zones (is it a CD95 by any chance?) you will probably have loads of programmable outputs. Consider using these to switch on lights in the event of a knock or double knock of the shocks etc. Burglars hate light!

Totally agree with the wired solution btw, it'll always be more secure.

beller b

Again just my own opinion..different people have different ideas about whats good or not. All downstairs I would fit shock sensors & contacts, the same for any upstairs windows that are accessable (ie over a garage or extension etc.) All other windows a contact is sufficiant the same with the skylights.In addition fit 2 PiRs (hall & landing).These PiRs as well as upstairs contacts can be omitted during a part set when you are in at night & wish to leave windows open.You say you have picked a 48 zone control panel how big is the house? If it an average 3-4 bed I would recommend using Astec , you can reduce the amount of wiring drastically..

patrido

great info here lads - tvm

beller b wrote:

You say you have picked a 48 zone control panel how big is the house? If it an average 3-4 bed I would recommend using Astec , you can reduce the amount of wiring drastically..

it's a texecom premier 48. the house is 3000sq ft, but even so i'm sure that i won't use anywhere near the whole 48 zones. but it doesnt cost much more than the premier 24 and it's got a few more features.

also, like lots of things the more split up into zones everything is, the more control you've got.

i was going to put pirs as backup into rooms that i don't want stuff knicked out of like living room, kitchen, sitting room, office as well as common areas like hall and landing. thats about 9 zones with just pirs. then i'm going to treat almost every room as a seperate zone. getting an sms saying "utility room window" is a bit more meaningful and informative than "downstairs zone"

plus a seperate zone for each of the external doors, seperate velux zone as advised earlier and room for expansion whenever i get around to building a garage. wouldn't be long outgrowing the prem 24.

murphaph wrote:

Now, I had 2 self contained shock sensor with built-in analysers. I have to say-they are nex to useless on PVC windows and highly effective on wooden door frames. I was told on a respected UK security installers website to expect this behaviour with PVC doors and windows and not to rely too heavily on shocks on those.

what do you mean by built in analysers? are these the combined shock/magnetic sensors, or something else entirely?

murphaph wrote:

If your gonna use PIRs, try to get dual tech ones that have 2 different detection methods built in, both of which must trigger to cause an alarm. IR alone can be set ff by radiators and sun on floors etc. Usually dual techs combine IR detection and microwave detection. False alarms are almost unheard of with these because the they have no false alarm sources in common.

those dual tech sensors look the business alright. sposed to be clever enough to filter out temperature changes in the room, etc. what about insects?

murphaph wrote:

If you're getting a panel that expands to 48 zones (is it a CD95 by any chance?) you will probably have loads of programmable outputs. Consider using these to switch on lights in the event of a knock or double knock of the shocks etc. Burglars hate light!

it's got some built in 12v 100ma outputs, but there's also an expansion relay module available. are these usually programmed using the pc software - i presume it's not using the control panel?

anyhow, should be good for switching on lights, triggering the geovision cctv server, releasing the hounds, etc

murphaph

patrido wrote:

what do you mean by built in analysers? are these the combined shock/magnetic sensors, or something else entirely?

The traditional type of shock sensor has a little gold-plated ball resting on metal contacts, it detects a shock by a momentary loss of continuity through the ball when it bounces. This loss of continuity has to be analysed by some form of programmable circuitry to determine is it an alarm or not. In most cases the panel itself will have at least some zones that can be programmed as 'shock zones' and the level of gross attack (sledgehammer on back door) and pulse count (prying with a screwdriver at a window frame) have to be programmed to the individual location, for example you generally don't even activate pulse count on a front door because a persistant kleeneze rep will trigger the alarm by knocking onthe door repeatedly . Built in analysers are shocks with all this circuitry and programming ability built into theshock sensor itself-the panel 'sees' a regular sensor which is held closed by a relay. These sensors obviously need a power supply as well as alarm wires to them. There's no advantage to built in analysers unless your panel doesn't support shock analysis (I had those things lying around as I used to work for a security products manufacturer )

patrido wrote:

those dual tech sensors look the business alright. sposed to be clever enough to filter out temperature changes in the room, etc. what about insects?

They won't trigger because of spiders :eek: , the microwave detector is insensitive to them. Remember PIRs don't detect heat-they detect changes in temperature EITHER WAY! So a classic false alarm cause is a bog standard PIR pointed at a hall door. Floor is warm from the heating or sun through the window, postie throws a cold packet from the front of his bicycle through the letterbox and off goes the alarm.

patrido wrote:

it's got some built in 12v 100ma outputs, but there's also an expansion relay module available. are these usually programmed using the pc software - i presume it's not using the control panel?

No idea mate. I know zip about Texecom other than that they are a respected panel in the industry. If you have the pc cable and software then you'll surely be able to programme every feature effortlessly.

Just a general comment. It may be stating the obvious but make sure you check the operational gap of your mag contacts. Make sure they actually open when you open your windows/doors beyond a gap that would allow a hand or something inside!

Also, you will have a tamper loop to wire. Every contact, shocjk sensor, PIR and junction box as well as the external bell box and sounders will have a tamper switch. If they're opened they sould cause a tamper fault. Now, some panels allow the zone alarm wires to be connected through a combination of resistors to enable the panel to detect either an alarm, or a tamper fault. If your panel doesn't support this and yu have 48 zones to play with, consider mirroring each alarm zone with your tamper zones. The alternative is one huge tamper loop covering ALL devices. This is bad cos you'll have a major pain troubleshooting a problem.

Lex Luthor

that was a good point about the differences between wooden windows & pvc. I have wood and the shocks work great....