Where exactly should you put surface contacts?

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PaulUszak

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Since recently dwelling on surface contacts, I came across this suggestion on a web site called Ultra Secure Direct.
upload_2016-8-12_0-49-23.png

I had always thought that the contacts went as far as possible away from the hinge, so on the left in the above diagrams. They suggest a 1/3rd of the way from the hinge so that movement of the door does not trigger a false alarm. Don't magnetic contacts have an operational range of approximately 15 -20mm? I would not have thought that a couple of mil lateral door movement due to wind would cause a problem. They advocate the same position for hinged windows too.
Does anyone have any comments, or is it not really an issue and I'm over thinking it again :unsure: ?
 
PaulUszak said:
Don't magnetic contacts have an operational range of approximately 15 -20mm?
Click to expand...

Not always. The advice to fit the sensor away from the edge is sensible if the door is able to move when locked. ( poorly fitting door and/or lock ) Though I would fit it two thirds away from the hinge as one third on a wide door could allow the door to open enough for slim burglar to gain entry without the sensor operating
 
A door contact when fitted should cause an alarm condition when the door is opened in the normal way at or before a 100mm gap is reached
 
that's depends if the money swings from the light fitting or not.

@flameport agreed, the door shouldn't move enough when shut to activate a door contact. If it does then you need to find the right balance or get the door fixed.

I will say that positioning at the bottom of the door risks foot traffic knocking the contact off the door but customers don't want them in plain view.

Must be very noise if the door is moving so much in the wind, and not very secure??
 
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