Electric Strikes: How, Where And Why?

As locksmiths, we control access. We install locks to keep people out and key those locks with different levels of security to permit only those authorized to gain entry. We install mechanical or electromechanical locks in order to accommodate the...

Depending upon the electric strike, holding force varies from less than 500 to more than 2,000 pounds. The electric strike installed should be compatible with the door. For example, a 2,000-pound holding force electric strike serves no purpose when installed to control a narrow stile aluminum glass door.

Electric strikes are equipped with a solenoid or a magnetic coil that secures and releases the keeper. The difference between a magnetic coil and a solenoid is the method of operation. A solenoid wiring is like a relaxed coil spring and a magnetic coil is like a magnetic that pushes a release mechanism.

Electric strikes are available in different designs including varying body sizes, recessed and surface mount and fixed and removable faceplates. One important consideration when retrofitting an electric strike is its depth. This is the cavity made by the keeper. Depending upon manufacturer and model, the keeper varies.


ROFU Examples

For the purpose of this article, we will use ROFU Electric Strikes to discuss the choices and options available when installing an electric strike. ROFU uses six-digit part numbers plus the finish designation for their electric strikes. The first two digits are the Series. They include the 14, 15, 17, 18, 19, 24, 26, 34 and 39. ROFU electric strikes are manufactured in Germany.

The Series part numbers include the size of the electric strike body, the Keeper and the function. Function options are Fail Safe, Fail Secure and “field reversible” Fail Safe/Fail Secure having the ability to be reconfigured in the field. The first digit of ROFU’s part number indicates the function of the electric strike. The number 1 is Fail Secure. The number 3 is Fail Safe. The number 2 is field reversible.

The second digit indicates the keeper type. The keeper is the movable forward part of the strike face opening that secures the latch or bolt. ROFU offers four different keeper types. They include the 33mm fixed (5) and 44mm fixed (4), the adjustable (7 and 8), and the rim mount (9) keepers.

The 33mm keeper is for residential or light commercial applications. The keeper is nickel plated brass that accommodates up to ¾” latch. The 15 series electric strike bodies are compatible with existing products on the market.

For commercial applications, the fixed 44mm nickel plated brass keepers can accommodate up to ¾” latch. The 17 and 18 Series electric strikes have a 44mm cadmium plated brass keeper that has ¼” horizontal adjustability, and will accommodate a ½” latch.

ROFU electric strikes are also identified by whether they are equipped with a solenoid or a magnetic coil. The first two digits, for example the ROFU 17, 18, 24 and 26 series electric strikes are equipped with solenoids. The 14, 15, 19, 34 and 39 series electric strikes have magnetic coils.

Note: The advantage of a ROFU solenoid equipped electric strike is the solenoid models “cannot be surreptitiously unlocked using an ‘earth’ (permanent) magnet,” according to the manufacturer.

The third and fourth digits are faceplate sizes and shapes to accommodate different door materials and lock applications. Hollow metal and aluminum door faceplates are generally smaller than wooden door faceplates. Some faceplates are positioned at the centerline and can be reversible for a left hand (LH) or right hand (RH) doors. These ROFU electric strikes are equipped with removable faceplates. For example the “02” faceplate is used in conjunction with a cylindrical lock and the standard 1-1/4” by 4-7/8” ANSI Strike. This faceplate can be removed and a different faceplate installed. For wooden doors, ROFU offers centerline, symmetrical (non-handed) faceplates up to nine inches long.

To provide options for one electric strike that fits popular preps, the ROFU non-handed 1800 kit comes with three faceplates, the 02, 03 and 04 faceplates. They are 1-¼” by 4-7/8”, 1-¼” by 6-7/8” and 1-7/16” by 7-15/16”. This adjustable keeper, Fail Secure solenoid equipped electric strikes comes with built-in MOV (Metal Oxide Varistor) that is used to protect against excessive transient voltage.

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