CQR SC570/WH/DD/G3 Grade 3 Double Door Surface Contact, Multi-Resistored, White

Overview

Magnetic contacts are reed sensors with magnets that tell the alarm whether a door is open or closed. This SC570 version is made for double door configuration, so a pair of doors can be watched from one contact.

It is the white, Grade 3, multi-resistored model of CQR's large surface contact.

How it works

• Reed switching: the reed switch stays closed while the magnets sit beside it, and opens when a door moves away.
• Multi-resistor board: several resistor combinations come pre-fitted. Keep the one the panel needs and cut out the others, so one part suits many panels.
• Tamper: cover, RFMS and MID tamper let the panel know if the case is opened or the contact is pulled off its mounting surface.

Where to use it

Use it on pairs of doors inside the protected area. Keep it away from damp or unheated spaces.

What the figures mean in practice

• About 10mm pull-in gap: Grade 3 contacts close only when the magnet is near, which makes them harder to defeat but means doors must shut squarely.
• Resistor types: A/B/D/E/I cover the common end-of-line schemes; check which one the panel uses before cutting.

Installing it

Line up the contact and magnet parts so the circuit closes only when both doors are shut. As a rule, test each leaf on its own with the panel in engineer mode.

Wire the alarm and tamper circuits to the terminals, then fit the cover so the cover tamper closes.

Planning your system

A Grade 3 contact only gives a Grade 3 result when the alarm panel and other devices are Grade 3 too. The British standard for intruder alarms explains the grades.

Run the circuit in alarm cable, and keep gaps tight: badly set contacts are a common cause of false alarms. For a non-resistored Grade 3 contact in grey, see the SC570/GY/G3/EN, and the wider range of door contacts covers flush and shutter models.

Standards and ratings explained

• EN50131-2-6: the part of the intruder alarm standard that covers opening contacts and how well they resist attack.
• EN50130-5 class II: the environmental test standard for alarm equipment; class II covers general indoor conditions.