CQR Surface Door Contact, Large, Multi Resistored, Grade 2, White SC570/WH/MULTI

What this contact is for

A magnetic contact tells an alarm panel that a door or window has opened. This one is a large format contact for wired systems.

The multi resistored design suits an installer who works on different panels. It can also suit a site where a contact is being replaced, because the resistor can be set to what the panel already expects.

How it works

• End of line and FSL: an end of line resistor lets a panel tell a healthy circuit from a cut or shorted cable. FSL, or fully supervised loop, carries alarm and tamper on one pair by using different resistor values.
• 3 terminals: its modes of operation are end of line and FSL, so plan the wiring around a resistor scheme rather than separate alarm and tamper pairs.
• Tamper: the cover and the mounting surface are both protected, with a microswitch doing the sensing.

Where to use it

Use it on windows and doors inside a building, including double doors. A large housing is easier to place on a frame with room to spare, so measure a slim frame first.

It is white, which may suit painted or uPVC frames. Check the magnet, 85 x 18 x 21 mm, has a flat place to sit on the door.

What the figures mean in practice

• Pull-in gap of 36 and 27: these are in mm, for the X and Y axes. Allow for a door that moves in its frame, and keep within the smaller figure if the alignment is uncertain.
• Steel frames: fixing a magnetic contact to steel often shortens its working gap, so test it in place.
• Rhodium: rhodium is a hard metal often used on switch contacts because it resists wear.

Installing it

• Select the resistor first: read the panel's manual for its resistor type, then select the type it expects, following the contact's instructions, before closing the cover.
• Mounting surface tamper: this detection is optional, so decide whether the job needs it before fixing the base.
• Testing: open and close the door with the panel in test, then check the tamper reports when the cover is lifted.

Planning your system

You will also need an alarm panel that supports one of these resistor types, and alarm cable for the run. Check the type before you order.

Grade applies to the whole system. This contact can be used up to and including grade 2, so a higher graded job needs a higher graded contact.

Standards explained

• EN50131-1: this is the general part of the European standard for intruder alarm systems. Grade 2 generally means low to medium risk premises.
• EN50131-2-6: this part covers opening contacts such as this one, and the certifying body is Kiwa FSS.
• EN50130-5: this covers environmental tests. This contact is rated Class II.