The Importance of Electric Strikes

The lowly, one-size-fits-all electric strike from 30 years ago now has new shapes, sizes and options suitable for any situation, and it can usually be easily installed in place of the existing strike with no problem. Electric strikes also help keep installation costs to a minimum by often allowing the owner to continue using their existing doors, frames and door hardware. There are electric strikes with motor-driven gate systems but the majority of electric strikes still consist of an electromagnet source, improved gate locking systems and a keeper.

One of the problems with an aftermarket installation of an electric strike is the latch location of the existing lockset. Mortise lock latch locations vertically on the door can vary by manufacturer. Electric strike manufacturers have solved this problem by making strikes with full-length keepers. Replacement electric strike faceplates are available with cutouts at different height positions on the plate to accommodate almost any latch position.

Another common problem is latches which either bind or have excess in and out play in the electric strike. A feature available on many electric strikes allows you to adjust the horizontal position of the keeper so the door can be easily closed and latched without binding, but will then have only a minimum of in and out door movement. While modern electric strikes are designed to operate even when there is minimal pressure exerted on the keeper, it is always best to eliminate any binding pressure caused by door-to-strike misalignment.

One distinctive feature of most electric strikes is the requirement for a large frame cutout. The cutout can provide an opening for someone to ‘knife’ the latch to an open position and bypass the electric strike. If the door lock hardware contains a deadlatching function, knifing may not be a big problem. In cases where only a spring latch is providing protection, a guard plate would be a suggested addition.

Several optional items can be added to enhance electric strike performance. If noise is a problem, a rectifier can be added into the low voltage AC power line. A rectifier changes the electrical source from AC to DC which eliminates the buzzing sound. If the originating power is already DC, a piezo horn can be added so a visitor is alerted when the electric strike is released. The low voltage requirement for electric strikes is usually 12 or 24 volts. Phone companies often use 48 volts because it is already available in their buildings for telephone equipment. Some electric strikes must be ordered for a specific voltage while other electric strikes are field-adjustable. Electric strikes can be ordered with monitoring switches which can send a signal when a door is not fully latched. Scar plates for botched installations and extender plates for extra thick door jambs are other available options. At least one company makes a product which includes a proximity card reader and an electric strike all in one unit.

Whenever installing an electric strike in a fire-rated door jamb, check with the Local Authority Having Jurisdiction (LAHJ) to be sure that any enlargement of the door jamb opening which is required for the new electric strike does not violate the fire rating of the door.

A recent variation to appear is the surface-mounted electric strike. These strikes are designed to be only approximately 1/2” thick in order to replace original surface-mounted strike plates on exit devices. Exit devices can now be electrified without mortising and by only drilling a few necessary mounting screw holes. Most of these surface-mounted electric strikes are especially useful for operating pullman-style exit device latches.

For More Information

Following is a partial list of electric strike manufacturers, their web sites and telephone numbers. A more complete listing can be found in Locksmith Ledger’s Online Buyers Guide at http://directory.locksmithledger.com.

Adams-Rite: www.adamsrite.com, 800-872-3267

Folger Adam: www.folgeradamedc.com, 800-626-7590

HES: www.HESinnovations.com, 800-626-7590

Rofu: www.rofu.com, 800-ALL-ROFU

RCI: www.rutherfordcontrols.com, 800-265-6630

Security Door Controls: www.sdcsecurity.com, 800-413-8783

Trine: www.trineonline.com, 718-829-6405

Von Duprin: www.vonduprin.ingersollrand.com, 317-613-8944

For additional Locksmith Ledger electric strike articles, visit http://tinyurl.com/strike1111.