CQR Flush Alarm Door Contact, Multi Resistor, Grade 3, Brown FC508/BR/MULTI/G3/EN

Overview

This contact sits inside the door and frame rather than on the surface, so it is out of sight once fitted. It is aimed at intruder alarm systems up to and including grade 3, and it comes in a brown housing.

Two parts make up the pair, the contact housing and the magnet housing. It has a screw terminal block, so no junction box is required.

How it works

While the door is closed, the magnet holds the circuit closed. When the magnet housing moves away from the contact housing, the circuit goes open and the alarm panel sees the change.

Normally closed is the usual arrangement for this, because a cut cable also opens the circuit and so gets noticed.

Where to use it

It can be used on double door configuration, in most intruder alarm systems up to and including grade 3.

Keep it indoors, as class II is for use indoors. The -15°C - +40°C range matters in unheated spaces such as outbuildings.

What the figures mean in practice

• Pull-in gap: this is the distance at which the magnet makes the contact operate. Measure the real gap between door and frame, and allow for movement over time, since a loose contact or a widening magnet gap is a common cause of false alarms.
• IP 4X: IP ratings cover solids first and water second. The X means no water rating is declared.
• Contact material: the switching contact is silver plated copper.

Installing it

• Terminals: 4 screw terminals, and no junction box is required.
• Resistors: end of line resistors let a panel tell a healthy circuit from a cut or shorted cable. Choose one of the selectable types, or fit your own.
• Wiring modes: the modes are DP, meaning double pole, and end of line/FSL. Follow the panel's wiring guide for which to use.

Planning your system

The job also needs an alarm panel with a matching input type, plus cable to the zone. Check that the system grade agrees with the Grade 3 rating before choosing it, because a lower-graded part can limit the rating of the whole system.

For other styles of door contact, including surface and heavy-duty types, compare them before ordering, especially where the door gap is large.

Standards and ratings explained

• EN50131-2-6: this is the part of the European intruder alarm standard that covers opening contacts. Read more in the guide to the intruder alarm standard and its grades.
• Kiwa FSS: this is the body certifying it to the standard and to environmental class II.