What are electric strikes?
Electric strikes are the devices that made it possible for you to say this to a guest waiting outside your apartment building: “I’ll buzz you in.” You push a button, and voila, you’ve let them in without having to leave your apartment and going all the way downstairs.
Electric strikes were first applied to New York high-rises. In the absence of doormen, or instead of employing doormen, home and office residents could simply open the locked building door by controlling the electric strike.
The door strike is that part of the door lock that goes in the door jamb, the one with the hole for the latch to sink into. Electric strikes replace that door strike. It works with most lock sets, and is a powerful security system when used in conjunction with access control devices like magnetic locks and electric latches.
Just push/pull to open
Unlike ordinary door strikes, electric strikes have a movable ‘gate’ called the keeper. The keeper either blocks the latch, or is out of the way so that you don’t have to use the doorknob or handle. If the electric strike is ‘open’, you can open a door just by pushing it. The latch or bolt can stay in its extended position.
If you own a store or an office, people don’t have to keep turning a doorknob to come inside.
In case of fire, electric strikes keep doors open for easy, life-saving exits.
Exclusive elevators, private offices, restricted rooms-- these often have electric strikes, and only those with access know the code or have the key/card to release
the door.
Convenience, Control and Safety
At home, think of a summer party and being able to go in and out with drinks and food in each hand without having to keep the door open and letting all the bugs inside and the air conditioning out.
In business, you control which doors the public and your trusted employees can access, and when.
A school kitchen and dispensary won’t be accessible to kids because only the staff know the code for the doors.
Stockrooms can be kept open while the stocking happens-- and locked with limited access the rest of the time.
As for security, an electric strike is impenetrable when used with a magnetic lock. The electric strike is an essential element of security, keeping the lock in place.
How does an electric door strike work?
The security of a door comes from three elements: the lockset, the doorknob or handle, and the strike. Door knobs and levers work by pulling in the latch bolt of the lock set so we can open a door, because otherwise, the door strike holds the latch bolt in place.
As we mentioned above, the magic of electric strikes is in their controllable keeper. Using low voltage, this keeper can be moved out of the way. This allows the door to open without manual retraction of the latch bolt. The latch just rests in the electric strike. When you lock the electric strike, the keeper holds the latch in place.
The bolt or latch has to be set in dead-lock: permanently extended and can’t be pushed back.
Most lock sets work with an electric strike, although you may need to install a new lock set to suit your purposes.
Types of electric strikes and how to select the right electric strikes for your home or business
Your choice of electric strike depends on the lock you’ve got. If you’re also changing the lockset, your choice depends on the door’s type and purpose. Think about the application and operation requirements. For example, a security upgrade for your main entrance may do better with a switch from a cylindrical lockset to a deadbolt in addition to the electric strike, or perhaps to a better cylindrical lock, at least.
What type of lockset have you got?
JMAC.com specializes in security systems, so the locks pictured here are all electrified or have secure keyless entry features. Click on each image for more information about that product. You would recognize these types of locks in your home or business.
Rim exits are often used in steel/wrought iron gates and in panic exits, while cylindrical, mortise and deadbolts are common in homes and places of business.
Each type of lockset has its corresponding electric strike.
Cylindrical
Mortise
Deadbolt
Rim Exit
What type of door is it? Single? Double? What’s the door material and the dimensions of the locks?
Electric strikes only work with single action inward OR outward opening doors. For double action swing-through doors, consider other locking options: solenoid bolts, magnetic shear locks or double action electric latches.
There are strikes suitable for nearly all door styles and materials, from timber, steel, aluminum to even the problematic uPVC.
What level of security do you need?
Light, Medium, High Holding Force
The electric strike is the source of mechanical control that keeps your doorway secure, keeping the lock in place. So electric strikes have varying strength, called the “holding force,” for different levels of security. But even those labeled “light” are strong enough, with 1200 lb holding force.
- Light: usually without holding force, runs on AC and used for low cost door entry systems
- Medium: 1,000lb + holding force, guaranteed two to three years
- High: 3000lb + holding force, guaranteed up to five years
Grading
Depending on your security requirements, and how much usage your doorway will have, you’ll need door hardware and electric strikes all with the same grading.
Grade 1 is the highest-- strikes and hardware go through cycle testing and static and dynamic strength testing to determine their grade.
If you need your doorway to meet a specific grading, choose all hardware with the same grading. Otherwise, your access point simply takes the rating of the product with the lowest grading. Your whole entryway is dragged down by its weakest point. See below for details on the grading for electric strikes.
Would you need to monitor the lock/strike?
See the status of your door: “Door closed and latched” or “Door closed and bolted.” Most manufacturers offer monitor strike kits and door status sensors for some
models of their strikes.
What power supply unit (PSU) is available (AC? DC?), or what would you install?
AC and DC electric strikes
AC voltage is only available for fail secure. It makes the familiar “buzz” sound when the power is activated. Fail-safe units are always run under DC power.
DC electric strikes are a better fit for more security, using a continuous and silent power supply both for fail-safe and fail secure setups. DC fail-secure doors only make a click when opened. If you want the buzzing sound, you can install a buzzer.
Historically, electric strikes used AC power. The buzz from releasing the lock of these fail-secure electric strikes coined the term, “buzzing someone in.”
Power Supply Units
Make sure you get the correct specification and match the PSU’s voltage with the strike’s tolerances. Avoid long and thin wire runs and always take into account what else is using the same PSU.
Fail secure and fail safe
Electric strikes have two configurations, fail-secure and fail-safe. New technology has made it possible for rapid switching between the two.
Put simply, fail safe needs power to lock. The door is open by default, the strike in an unlocked position. Fail secure needs power to unlock. The door is closed by default, the strike in a locked position.
Fail secure electric strikes are the most commonly used for security and power conservation. Power is applied to open the door. This power is activated through keys, codes, cards or buttons operated by authorized people, i.e., you and your neighbors if you’re in an apartment building.
Fail-safe electric strikes are often used for stairwells so that during a power failure or a fire alarm, people can get out and firefighters/emergency crew can come in without needing keys or access codes and cards.
Electric strike vs. magnetic locks?
There’s some confusion about electric strikes and magnetic locks. There should be no ‘versus’ between them. They work together.
Magnetic locks are awesome locking devices. They’re strong. Unbeatable. But they’re always fail-safe. They’re always on DC power-- they need that power to
stay locked.
Without power, the door opens.
This is where an electric strike comes in. A fail secure electric strike would keep a door locked even when the power goes out.
Remember that electric strikes are NOT locking devices by themselves. An electromagnetic lock takes care of that security instead. One of the best access control setups is an electric strike and electromagnetic lock together.
Grading, Quality Regulation For Electric Strikes
The American National Standards Institute (ANSI), Builder's Hardware Manufacturers Association (BHMA), and Underwriters Laboratories Inc. (UL) make sure performance and durability levels of your electric strikes are up to the standards they’ve established.
When you look at locksets and electric strikes, you’d see Grades 1, 2 or 3. Grade 1 is the highest.
The following tests determine the grading of electric strikes:
- Cycle testing - electric strike is cycled with compatible hardware at a rate not to exceed 30 cycles per minute
- Static strength testing - with the electric strike in the locked position, continuous force is applied to a specified point on a door at a rate not slower than 10 pounds-force (44N) nor faster than 20 pounds-force (90 N) per second until the rated static strength is reached and held for 1 minute prior to separation
- Dynamic strength testing - a ram is used to deliver 5 impacts at a specified point on a door at the rated dynamic strength
How To Install Electric Strikes: Tips, Tools and Electronics
Electric strikes are easy enough to install-- all you need are the right information and the right tools. This section is a general guide. Refer to your installation guide for specific instructions for your specific electric strike.
1. Make sure you've made the right choice for the purposes of your electric strike.
- See the selection how-to in this guide.
- Is your chosen electric strike strong and durable enough?
- Is it a match for the lockset, whether it's an existing or a new one? If you have double-doors, is the mullion or inactive door a good fit for the strike?
- Do you have the correct voltage from your power supply?
- What does your application need, fail secure or fail safe? Have you picked the matching strike?
2. Familiarize yourself with the specific model you are about to install.Read the manufacturer's installation template and instructions. Chat with the supplier to make sure you get everything you need for the installation.
3. Gather your tools together.
- Protective glasses/shield
- Drop cloth to catch debris
- Masking tape - to mark off measurements and to protect the frame during cutting
- Reciprocating saw - for use if you have a hollow metal and aluminum frame; a power saw with a blade that alternates between forward and backward movement.
- Die grinder - for use if you have concrete-filled metal frames or hollow
- Dremel - slow but sure and clean, for smaller cuts, repetitive surface cuts
- Jigsaw - for cutting curved and irregular lines
- Wood chisel or a router - to hollow out the surface and to create the holes you need for installation
4. Mark off the dimensions needed in the door frame.
5. Match your cutting tool to your material, and make the required cuts in the frame according to your electric strike's installation guide and the anatomy of your electric strike.
Make the measurements and necessary tool prep according to:
- the faceplate - has the mounting holes for securing the strike to the frame. Determines the height and width dimensions of your cuts, also the shape of the corners: square or round
- the keeper - determines the depth and placement of your strike to match the placement of the lock’s bolt or latch
- the lip - bridges the gap between the faceplate and the edge of the door frame and provides a path for the latch to enter or exit the electric strike. You might need lip extensions for certain frames and mounts
- Metal frames
- Metal frames usually have strike preps
- Cut out the ANSI specified extension 'lip' of the frame
- If you need to cut the dust box to make room for the strike, cut only the bottom section and don't alter the welded mounting tab sections
- If no strike preps is pre-installed, or if the ANSI dust box is completely removed, install mounting tabs in the frame
- If the frame is hollow, inserting the strike would be easy
- If the metal frame is concrete-filled, hollow out a space for your electric strike
- Wood frames
- Hollow out a space large enough for the electric strike
- Cut inside the lines, leaving enough margin that you can simply chisel or file away for a clean cutout
- The strength of your electric strike depends on how strong it's secured to the wood: select a strike with a longer faceplate so that the mounting screws have a
- good distance from the strike cutout and a good space to be strongly anchored to the wood.
- Aluminum frames
- You may need to add an extended lip to the front of the electric strike to accommodate the longer reveal (the distance between the strike and the frame face),
- in the case of strikes that need to be installed a distance away from the edge of the frame
- Surface-mounted
- You may need faceplates to accommodate the clearance between the housing cover of the exit device and the frame
- Inactive door mounting on double doors
- Similar to wood and metal installations
- There are electric strikes for this specific application.
- To bring power to the electric strike, install an electrified hinge or power cord for a power transfer from the frame to the door, and then drill a horizontal hole
- in the door and install power leads there toward the electric strike cutout
6. Electronics, power sources, voltage and current
- The longer a current has to travel, the less voltage and amperage (strength) it packs. Keep conduction (wiring) short. If the wiring has to be longer, it has to have
- a larger gauge to avoid voltage drops and problems with your electric strike.
- Double check and triple check that you’ve got the correct specifications for your PSU and voltage.
- Exceed the required current and amperage with a margin of 20-25% to make up for voltage or current loss due to conduction.
- Relay switch
- Fail secure electric strikes are commonly in an open switch configuration since the strike is locked without power. The circuit closing unlocks the strike.
- Fail safe electric strikes are in a closed switch configuration to continuously provide power and keep the strike locked. The strike is unlocked without power
- when the circuit is opened.
Electric Strike Problems: Basic Troubleshooting
Strike doesn't lock or unlock
- Cause: No power or incorrect voltage used.
- Solution:
- Confirm that you have the correct input and output voltages. Use a multimeter.
- Confirm that all connections are good and secure.
- Cause: Strike is stuck.
- Solution:
- Confirm that the keeper works fine when the door is open. Adjust the door or strike.
- Check the strike cavity depth matches the lock set's bolt or latch.
Door doesn't latch
- Cause: Warped or sagging door.
- Solution: Realignment.
Lock is not dead latching
- Cause: Improper installation or warped/sagging door.
- Solution: Adjust or replace the door. Fix the alignment or the horizontal adjustment of the deadlatch and the lip.
Strike makes a buzzing sound or does not buzz.
- Cause: Improper power supply.
- Solution: Match the proper AC (for buzzing) and DC (for silent) power supply. Or install a buzzer.
Burnt smell coming from insert.
- Cause: Improper voltage and/or improper installation.
- Solution:
- Fix all connections tight and secure.
- Make sure you're using the correct voltage and connectors.
|
