CQR Grade 3 Door Contact, Surface, Multi Resistored, Brown SC517/BR/MULTI/G3/EN

Overview

Door contacts come in two parts: a contact housing on the frame and a magnet housing on the part that moves. This is the surface version, so both parts sit on the face of the frame and door rather than being let into them.

It suits installers working to a grade 3 specification on a wired system. The brown housing may suit darker timber frames.

How it works

• Switch and magnet: the magnet usually holds the switch in its normal state. The contact type is Normally Closed, so parting the two housings opens the circuit.
• End of line resistors: these usually let an alarm panel tell a healthy circuit from a cut or shorted cable.
• Magnetic interference detection: this is usually meant to catch a magnet held near the contact to fool it.
• RFMS: this stands for removal from mounting surface, and it sits alongside MID as tamper protection.

Where to use it

Use it inside a building, on windows and doors. Class II is the indoor class, so an exposed door is outside its rating.

Double doors are covered as well. How each leaf is wired into the zone is a panel design point, so settle that before fixing.

What the figures mean in practice

• Pull-in gap: 19 and 10 are the millimetre figures for the X and Y axes. Measure with the door shut, and leave some margin for a door that moves in its frame.
• Axes: the figures cover X and Y only, so check the fit if your door approaches on another axis.
• Resistor letters: panels ask for different values, so match the letter to the panel's wiring guide, or fit the values it asks for using your own.

Installing it

• Modes: DP means double pole, and end of line is the other wiring mode. FSL usually means a fully supervised loop, so check which of these your panel expects.
• Spacers: contact spacers are an option, so check the code with CQR. A spacer usually lifts a part so that the door side and frame side line up.
• 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, set up for the resistor type you choose, so check the input first.

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: the European standard series for intruder alarm systems, with grades that rise with the risk being protected. EN50131-2-6 is the part covering opening contacts.
• EN50130-5: the environmental test standard for alarm equipment, which is where class II comes from.