The installation of an electric strike or door opener can normally be performed in four or five hours, depending on the construc- tion of the door and the construction of the building. Wooden doors with a shallow electric strike provide the easiest instal- lation. Aluminum doors or deep electric strikes create more difficult installations.
Let’s begin by looking at the installation of an electric strike on a wooden interior door (Figure 46). The first step in instal- lation is to remove the trim molding around the door’s knob side. Usually, it’s easiest to use a nail set punch to punch the nails inward until they no longer grip the molding. Once the nails are recessed, the molding can easily be removed from the door- jambs or frame.
With the molding removed, you should see a slight cavity be- tween the jamb and the wood or steel studs that surround the door. You’ll run the wires or cable into this cavity to power the electric strike’s coil.
FIGURE 45—A continuous-duty electric strike uses a normally closed push button or keyed switch to turn off the coil.
The next step in installation is to cut an opening through the jamb for the electric strike or door opener. A template is usu- ally provided with the electric strike to help you locate the opening’s height and width properly. The hole’s depth should also be listed on the template, or can be measured from the lock face to the rear of the assembly or coil.
The opening for the electric strike can be cut in many ways. The best method is to use a router, which is a high-speed wood or (soft) metal cutting tool that uses drum-shaped bits. If you don’t have a router, the next best cutting tools are a saber or jigsaw and a drill. First, drill a hole at each corner of the opening. Next, take the jigsaw and cut from one hole out- ward around the opening to the next hole. Continue cutting until all four holes have been connected. Finally, use a wood chisel and hammer to remove the wood material left in the opening’s center.
A slight recess must also be cut into the jamb for the faceplate of the electric strike. As before, a router is the best tool to cut this recess. Set the router to cut the proper depth; move it around the recessed areas to remove only the desired depth of jamb material.
FIGURE 46—Once the molding is removed, you should see a gap between the jamb and the support stud.
A wood chisel can also be used to cut this recess. Once the dimensions are marked on the jamb, simply chisel around the jamb on the outside lines of the recess. Once this is done, use the chisel as a plane and remove the jamb material to the proper depth from the deep hole toward the outside of the recess area. Use light hammer taps to prevent digging too deep in the jamb. This is shown in Figure 47.
A mating hole and recess will also have to be cut into the door for the latch and the strike plate. The hole can normally
be drilled using a round drill bit of the proper diameter. The re- cess can also be cut with a router or a chisel. Take extreme care that the hole and recess line up with the opening you’ve cut in the jamb.
The next item to work on is the push button or key switch that is used to energize or de-energize the lock’s coil. A typi- cal box and push button is shown in Figure 48.
FIGURE 47—Use a wood chisel to remove about one-eighth inch of material above and below the cutout.
The flush mount box shown can be used for mounting within an inside or an outside wall. Surface mounted boxes are also available. To install a flush mounted box, you must cut a hole into a wall the size of the box. A saber or jigsaw is the easiest tool to use. Mark the wall with the size of the opening required and drill the holes at two diagonally opposite corners. Use the jigsaw to remove the wallboard material between the holes. The next assembly to mount is the power supply. This as- sembly is normally mounted in the basement, in a convenient location near an electric service junction box. Many poor installa- tions feature a transformer mounted to a wooden basement beam by means of wood screws. A better installation involves mounting the transformer to the cover of a standard electrical junction box, as shown in Figure 49. If a fuse, rectifier, or tem- perature controller are part of the power supply, you can add it to the assembly. Preassembled power supplies are also available.
FIGURE 48—A typical flush mount box with a push button switch is shown here.
Now it’s time to run the wires. Normally, a two-wire cable is used to run electricity from the power supply to the switch box and then to the coil. As a general rule, you can use 18 AWG gauge wire to connect these items in the system. How- ever, if the installation requires wires over 200 feet long, you should install 16 AWG wire. This larger diameter wire pre- vents a voltage drop along the wire that could influence coil operation.
To perform the physical installation, you’ll have to drill holes and run the wire. Drill a hole from the basement through the interior stud, just below the switch or push button box. Drill a second hole between the doorjamb and the supporting stud directly below the electric lock’s desired location.
To pull the cable through these holes, you can use a piece of stiff wire or an electrician’s fish tape. A fish tape is actually a thin spring steel band that’s released from a roll as you pull it. Figure 50 illustrates the use of a fish tape.
When pushing the fish tape or wire through the switch box hole, it’s rather tricky getting it to go through the hole you drilled in the plate stud. If possible, have a colleague in the basement catch the end of the fish tape or wire with a hooked piece of wire or coat hanger.
The next step in the installation is to mark one of the cables. Wire markers are available at electrical supply stores. These FIGURE 49—The power supply can be mounted either to a wooden beam or to a piece of wood between the beams, as shown here.
wire markers come in number and/or letter varieties and peel off from a card. You can wrap the number or letter strip around one of the two cables to identify it. You could also simply mark one cable with colored tape.
Once the wires are marked, tape them to the fish tape or wire and pull them up through the wall into the switch box, leaving at least six inches of wire for you to make your connections. With the wires in the switch box, take the cable that you iden- tified with the marker or tape and run it over to the power supply. This cable can simply be stapled to the bottom of the beams using insulated staples. However, a more professional installation results from running the wire through holes drilled in the beams. Next, run the cable to the coil, passing it up through the hole drilled between the jamb and the sup- port stud. Now all of the wiring is in place.
When connecting this system, start at the electric lock and work backward through the system. The power supply will FIGURE 50—Cables can be easily pulled through a wall by using a fish tape or stiff wire, as shown here.
be the last item to be connected. Start at the electric lock’s coil. Strip the cable jacket from the wires as shown in Figure 51. The cable’s jacket should be stripped back about three inches and each wire should have about one-half inch of insulation re- moved. Use a pocket knife or electrical wire stripping tool (which is quicker and easier) for the wire stripping.
The wires in the cable are normally connected to the coil’s leads with wire nuts. When selecting wire nuts, use a nut that’s rated for the number of wires and the gage of wire you’re using.
Most wire nuts are also color-coded. (You’ll normally be using a wire nut of an orange color.) Now, place the two wires together as shown in Figure 52. Don’t twist them to- gether. Simply place the wire nut over the two wires and turn it until it’s tightened. Use electrical tape to cover the wire nut and the wires just below the wire nut. Repeat this process for the second wire group.
With the wires connected and taped, mount the electric strike in its cavity in the jamb and install the retaining screws. Leave the molding off the door, in case you experience prob- lems while powering up the system.
The next place to make circuit connections is at the switch box. As before, strip the jacket from the cable and strip each wire. Take two of these wires of the same color and install a FIGURE 51—Strip the cable
jacket and wires as shown here. Take care not to dam- age the insulation on the wires.
FIGURE 52—When using wire nuts, strip the wire back one-half inch, hold the wires together, and then twist the wire nut onto the wire ends. Tape the joint when you’re done.
wire nut; tape as you did earlier. The remaining two wires are attached to the switch. Nor- mally, a solderless terminal is used for these connec- tions. These termi- nals are shown in Figure 53. These terminals are used with a crimping tool to make a secure connection on the wire. The wire end is stripped back about three-eights to one half of an inch and placed inside the barrel of the connector. The crimping tool is then placed over the barrel and squeezed to crush the barrel onto the wire.
Solderless terminals are easy to connect to the push button or keyed switch’s terminals. Simply loosen the screw for the forked terminal or remove the screw for a ring terminal, install the con- nector, and tighten the screw. With solderless terminals, you won’t be fighting with those few strands of wire that always seem to fail to be captured by the screw. When the switch box is wired, attach the cover to the box with the screws provided. On some installations, a pilot light may also be part of the switch box. This pilot light is wired to the circuit as shown in Figure 54. One lead of the pilot light is placed inside the wire nut where you joined the common leads. The second lead re- ceives a solderless terminal and is placed on the side of the switch that connects to the lock’s coil. With this system of wiring, the light is on until the button is depressed. In a fail secure system, the light comes on only when the button is depressed.
FIGURE 54—If a pilot light is connected to the circuit, it’s usually connected at the push button as shown here.
FIGURE 53—Solderless terminals simplify wiring to push button switches and key switches.
The final wire connections are made at the power supply. If the coil is an AC coil, place the two leads from the cable di- rectly to the screw terminals in the transformer. If a bridge rectifier or temperature limiter is present in the system, con- nect the cable to these devices and then connect these devices to the transformer’s secondary. Now, make sure that the AC power is disconnected and attach the transformer’s primary to the fuse, if present, and to the AC line.