CQR Grade 3 Door Contact, Large Surface, 6 Terminal, Brown SC570/BR/G3/EN

Overview

Door contacts come in two parts, a contact and a magnet. Both fix to the surface rather than being let into the frame or door.

The brown finish may suit darker timber doors.

How it works

• Two switches: it has 2 switches and SPST form A. SPST form A is usually a single switch path that stays closed only while its magnet holds it.
• Magnetic detection: this is usually meant to catch a magnet held near the contact to fool it.

Where to use it

As a rule, environmental class II is the indoor class in EN 50130-5, so keep it inside a building.

It suits a job calling for a larger surface contact on a system specified to grade 3.

What the figures mean in practice

• 10mm pull-in: this is a small gap, so the door needs to sit steadily in its frame for the contact to stay reliable.
• 500mA @ 12Vdc: treat this as the limit for anything the contact switches, and stay within it.

Installing it

• Spacers: a 5mm spacer comes in a pack of 10, under a code that ends WH. Check the colour suits a brown contact before ordering.
• Terminals: there are 6, so follow the markings on the board.
• Testing: as a rule, open the door with the panel in test mode and confirm the zone responds, then check the tamper.

Planning your system

In most installations, a wired contact needs cable back to a zone on an alarm panel, so check the input it expects, including any resistors.

In practice, an intruder alarm is usually rated by its lowest graded part, so one grade 3 contact does not make a whole system grade 3. Designs often mix motion sensors with contacts to cover entry points.

Standards and ratings explained

• EN50131-2-6: the part of the European intruder alarm standard that covers opening contacts. Grades rise with the risk being protected, and the guide to British Standard grades sets them out.