Installing Electric Strikes

♦ Installing Electric Strikes – skilled installation of electric strikes gives smaller alarm and access control companies additional revenue streams and a competitive advantage.

In a typical electric strike installation, there are 2 key components. The strike is fitted into the door jamb and has a bolt pocket that holds the latch securely. When the strike is opened, its pivoting lip – or keeper – rotates away from the pocket, allowing the bolt to be pulled away. The latch is embedded in the door and has no moving parts or power demands.

The strengths of electric strikes include their ability to handle high traffic areas effectively (in very high traffic, magnetic locks can be faster), and the fact they cut down on manpower requirements. Electric strikes also allow timed opening, multi-functioning and interfacing with integrated security and safety systems.

Strikes give positive door status and lock status indications as well as allowing remote and automatic door control. They eliminate the costly suiting of mechanical locks and end the need for key cutting and copy controls. Using an overall access system with electric strikes allows administrators to reprogram locks remotely.

There are things to consider when buying electric strikes. For a start it’s important that solenoid bolts are continuous duty or CDR rated if they are fail-safe. Fail-safe locks should be DC-powered and a CDR rating is necessary to ensure they don’t wear out early due to being constantly energised against a spring. Non-CDR rating mean a large current draw and an unwelcome build-up of heat that could slow the mechanism down.

Installers and specifiers should also ensure any fail secure locks installed are intermittent duty rated (IDR). These locks need power to pull a bolt out of a lock or to open a strike plate. The periods of idleness these locks experience mean it’s vital that the right amount of magnetism is generated by the lock when needed. Too much current would blow a fuse and too little would cause the lock to open slowly or not at all.

Handling Installations

Before you set out to the site before access control installation, set up the locks properly at the work bench. First, check to make sure the DC diode that crosses the positive and negative wires is already in place. If it’s not, the diode will be included in the packaging. Locate it and tape it to the lock. Next, check if the lock will fail safe or fail secure in the event of power failure.

If the lock needs to be set up manually, remove its cover and access the lock’s relay. The brass locking pins can be removed and their insertion pattern changed to fail safe. Decisions about fail safe and fail secure will be influenced by a site’s application and the customer’s requirements.

Good electric strikes are supplied with a template to assist with installation. Once at the site place the template on the door then mark it out so you can make the necessary cuttings. Cut out both top and bottom marks on the jamb as well as the markings on the opening edge of the door and once your initial cutting is completed, use the lock as a template.

In a good installation, the lock will be a press fit. Never overcut to allow for imperfections in your work. Any movement in the lock may impact on the tolerances of the lock and lower its security levels.

Next step is to put in the cable. The method you’ll use will be dictated by the construction of door frames and walls. You’ll either come down the through the wall and then through the frame (timber frame, timber door, gyprock wall) or you’ll conduit down the wall and come in through the frame from the side (concrete-filled, steel frame, steel door, cement wall).

Never use external conduit runs on the unsecured side of the door and try not to use them on the inside either. If you have to install cable this way, be sure to use steel conduit and if there’s camera support for the door, include the external cable run in the camera’s field of view if possible.

Major challenges will be fire doors. They have a fire-rated steel frame filled with cement to absorb heat and to resist buckling. Once your template is cut, use a cold chisel or similar tool to carve out a cable channel in the cement and then drill a hole through the jamb or the wall to carry cable from the lock to the controller.

Once the holes are drilled for wiring, take the cable back to an input on the door controller located in the closest electrical riser or wiring closet. Ensure your wiring is neat, firmly secured and tagged so it’s way to identify. The cable will have a pair of power wires and additional wires reporting lock status including open, closed or alarm.

With the wiring in, you can look at the installation of the lock itself. Drill the top and bottom holes then tap them to suit the screws supplied. To give yourself a third hand, turn the lock back to front and screw it to its top positioning hole as you connect the exposed wiring. The practise will ensure you don’t use too much wire and it’ll get the lock closer to your face for the careful work needed.

Now twist the positive and negative wires together, placing the DC diode in position across them. The anode of the diode will go to the positive and the cathode to the negative wires respectively. You then solder the diode into place using the minimum amount of solder for a firm joint.

Once the solder has set, fold the joint down so it can be heat shrunk. If it’s not your practise to heat shrink soldered joints, it should be. Covering connections reduces the possibility of short circuits and costly maintenance call-outs.

Before you turn the lock back around after removing the third hand screw, make sure you label wires and once this is done, put the lock into the door making sure wires don’t squeeze out the sides. Screw the lock into position making sure the pivot lip is correctly aligned with the latch. As you go through your commissioning procedure, check that door handles are correctly orientated, and egress is possible from the secure side of the door by not the unsecured side.

Now go to the reader and test the lock’s function using the appropriate credential or switch. The controller will power up the lock and the pivot lip will rotate, releasing the strike.

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