Power Supplies: Fueling Today’s Access Control Systems

Sept. 1, 2016
Door controllers, motion detectors, pushbutton door releasers, switches, card readers and keypads all have one requirement in common: a reliable power supply

Operating power is a necessity when it comes to the access control systems that locksmiths install and service. DC (Direct Current) power is required at the head-end control system where user and audit-trail data is processed and stored. DC power also is needed to operate the modems that carry data from one side of a large building to the other, from bottom to top in high-rise structures, throughout large campus settings, from one end of a city to the other, as well as across entire nations—from one end of the globe to the other.

For decades, the conventional PSTN (public switched telephone network) has carried access control data from one place to another in a most reliable manner. More recently, the National Broadband Infrastructure (NBI), as part of the Internet, has proven itself equally adept at moving data from a protected site to a system’s respective point of control.

Although there have been many advances in access control technology throughout the years, at the end of the day the effectiveness of these changes still comes down to “cost versus benefits.”

The World Turns on Power

Power is required for the operation of all aspects of an electronic access control system. Whether it’s the door controllers that connect to a head-end CPU (central processing unit) or the various devices that surround system-active doors, you can bet there’s one or more power supplies lurking in the background. Examples of this include egress motion detectors; manual, push-button door releases; door security switches; card readers, as well as fobs and keypads.

Power supplies are especially necessary where it comes to electrified locking hardware whose purpose it is to control and regulate foot traffic into and sometimes from commercial, institutional, and private multi-tenant buildings.  Examples of electrified locking hardware include electric door strikes (EDS). electromagnetic locks (EMLs), and electric bolt locks (EBLs).

In outdoor parking lots and buildings, power supplies also provide the means whereby motorized and hydraulic gates, along with their controllers, operate on a daily basis. Where gate controllers operate using 12VDC or 24VDC power supplies, the gates themselves operate from 120VAC or 240VAC. In some cases you, as the installer, can choose which of the two that is used.

In this Locksmith Ledger article we’ll take a look at conventional and intelligent power supplies, the latter of which provides power to network-connected devices. This includes the use of PoE (Power over Ethernet)-based applications where network equipment is powered through the same cable that carries access data in a network setting.

Code and Standards Compliance

Power supplies, just like door assemblies, locks, and other hardware, are subject to a number of standards and codes that seek to assure quality and sustained operability. For example, because of building codes, fire regulations as well as other governmental statutes and mandates require that access control power supplies provide a high level of performance as defined by a number of standards compiled, adopted, and published by Underwriters Laboratories (UL).

To assure that power supplies meet these standards, equipment manufacturers pay UL and other third-party testing companies to put their products to the test in a laboratory environment. The objective is for UL or some other third-party testing laboratory to list and label these products accordingly. The power supplies you use must bare these listing labels so local AHJs (authorities having jurisdiction) can verify system-wide compliance.

For example, according to Honeywell Power, “These power supplies are UL listed for access control (UL294), fire alarm (UL1481) and burglar alarm installations (UL603), and conform to NEC requirements” (http://bit.ly/29PzzrJ). NEC is an acronym for National Electrical Code, also known as NFPA 70, as compiled, adopted, and published by the National Fire Protection Association (NFPA) of Quincy, Mass.

According to Comptrol of Irwin, PA, “UL294 is the standard of safety for Access Control System units that all access control systems must meet. UL294B is a newer standard, specifically for the use of Power over Ethernet (PoE) components used within access control systems where PoE is the primary power source” (http://bit.ly/29R9KKr). UL294B in particular provides the necessary performance parameters associated with PoE-based power supplies, thus resulting in what we commonly term “intelligent power supplies.”

PoE, which is an acronym for “Power over Ethernet,” pertains to the provision of power to network-enabled access control devices through the same Category 5e and 6 cabling that carries access control data from one end of a facility to the other.

Additional standards and codes that must be followed include ADA (Americans With Disabilities Act); UL 2044 Commercial CCTV (closed circuit television);  CAN/CSA C22.2 No. 1-04, Audio, Video, and Similar Electronic Equipment; CSFM (California State Fire Marshal); FM (Factory Mutual); and ULC (Underwriters of Canada).
In all likelihood, the network side of an access control installation will be handled by the client’s IT (Information Technology) department. In many cases your client may have an outside IT subcontractor, or you may decide to partner with a local IT company by prior arrangement. When working with the client’s own IT people, be sure to spell this out in your sales agreement/contract so there are no misunderstandings.

Operating Voltage and Voltage Drop

Installing door strikes and electromagnetic locks for use in access control is fairly simple and straightforward. There are, however, a few things you need to know before you begin. Probably the most fundamental and basic is the relationship between voltage and current, especially from an installation standpoint.
Let's take the Model 1510 EML, manufactured by Security Door Controls (SDC) of Camarillo, CA. According to the manufacturer's specifications, the 1511 draws a total of 350mA when using 24VDC or 670mA when using 12VDC (http://bit.ly/2a7tXun). The fact is, many of the power supplies in use for access control allow the installer to choose either voltage/current.

With the above paragraph in mind, please notice the voltage-to-current relationships between the 12VDC and 24VDC EMLs. Note that when we go from 12VDC to 24VDC, the current requirement changes from 670mA to 350mA respectively, which is almost 50 percent less. Operating at a lower current draw also results in lower operating temperatures at the power supply, thus extending its life expectancy. And the final benefit associated with using 24VDC relates to the size of cable that you need to install from the power supply to the EML or EDS.

Calculating a Common Field Application

In a typical installation with the model 1510 EML, we have a linear distance of 35 feet between the electrified lock and a 12/24VDC power supply. You already have a roll of 16-gauge, two-conductor cable in the warehouse, but the question is whether 16-gauge conductors are large enough to carry a specified current of 670mA between the EML and the power supply using the 12VDC output.

To determine the answer, use the voltage (Volts)/current (Amps)/power (Watts) calculator, available from Calculator.Net (go to: http://bit.ly/2aiRR5Q). 

First, determine what the voltage drop will be across the cable you’re about to install between the access controller and the EML. This will tell you whether 16-gauge is large enough for the specified EML.

Note: the V/I/W calculator requires the linear distance between the power supply and EML, which is 35 feet. However, some online calculators will require you to double the linear distance because current actually flows 35 feet to the lock and another 35 feet back to the power supply.

Enter the following numbers into the Calculator.Net online calculator, including the linear distance of 35 feet. Note that the specification of 650mA must be converted into Amps. To do that, multiply 650mA by 10-3 (650mA X 10-3 = 0.650A). One shortcut is to simply move the decimal point in 650.0 three places to the left (10-3) to get 0.650A.

Calculate as follows:

Power Supply Voltage: 12VDC

EML Specified Voltage: 12VDC

EML Specified Current: 0.650A (650mA X 10-3 = 0.650A)

Total 16-Gauge Cable: 35 feet

Allowable Voltage Drop: 10 percent or up to 1.2VDC

Minimum allowable voltage at the EML: 10.8VDC

The resulting numbers:

Voltage drop: 0.19

Voltage drop percentage: 1.58 percent

Voltage at the end: 11.81

As a general rule of thumb, the voltage at the EML should be no less than 10 percent of the lock's specified voltage, or:

12 X 0.1  = 1.2 

12 – 1.2 = 10.8VDC

As you can see, the minimum voltage required at the EML is no less than 10.8VDC. Comparing this to the results from our Calculator.Net calculations ‑- which is 11.81VDC -- we see that 16-gauge cable will work.

There are other online tools available specifically for this purpose, such as LifeSafety Power at http://bit.ly/2a2GWwj and Altronix http://bit.ly/2aEf2GN.

Where to Find Power Supplies

Access control power supply manufacturers may or may not provide IP-based intelligent power supplies. In most cases the latter are designed for specific IP-connected access control systems and so they are usually made by third-party manufactures and private listed/labeled accordingly. In many cases you can actually use conventional power supplies in networked access control systems.  Always read and follow the manufacturer’s specifications and do what is specified in their installation/programming manuals.

The following is a list of power supplies with a brief write-up on each one. Be sure to follow the provided links to visit each manufacturer’s website for additional details.

Altronix, Brooklyn, NY: Trove enclosures combine Altronix power with access controllers and accessories from leading manufacturers. Trove simplifies board layout and wire management, greatly reducing installation and labor costs, and provide the versatility and scalability installers need to easily configure their products. Backplanes are available for Mercury, VertX, AMAG, CDVI, KABA/KeyScan and Software House access controllers and accessories. Altronix has also introduced Trove1, a compact enclosure that accommodates CDVI, HID/VertX and Mercury controllers. All Trove units include a cam lock, tamper switch and mounting hardware. For more information, go to www.altronix.com.

HighPower Security Products, Meriden, CT: The model 505 Lightning Regulated Power Supply provides power in conventional access control systems. It’s a general purpose power supply featuring selectable 12VDC or 24VDC with a 1A output and integrated battery backup. The 505 access control power supply is of a linear design, which means it will work with sensitive electronic equipment, such as card readers, door controllers, as well as electric strikes and electromagnetic locks. For more information, go to: http://bit.ly/2a2B9Xv.

Honeywell Power Products, Northford, CT: The model HP600ULACM8 is a dual voltage (12VDC/24VDC) power supply with HPACM4 or HPACM8 access power controllers to be used with access control systems. This conventional power supply offers 4 or 8 independently controlled, power-limited PTC protected outputs. For more information, go to: http://bit.ly/29Y1OUD.

Life Safety Power, Mundelein, IL: The FLEXPOWER ISCAN is an intelligent power management system for security and life safety applications. The iSCAN150-8 provides eight activation inputs and eight monitored and controlled relay outputs. The eight managed inputs are capable of voltage or dry contact activation and the outputs are programmable to either of the two system voltages, fail-safe, fail-secure, fire alarm over ride, AC loss over ride for egress lock control and more. For more information, go to: http://bit.ly/2apoT75.

Napco, Amityville, NY: The Napco Platinum power supply model NP-LPS6-24VDC is a linear power supply/charger  that offers selectable voltage filtered/regulated outputs of 6, 12, and 24VDC. Maximum battery charge current is 300mA with 1.5A continuous current rating at 6 and 12VDC with a current output of 1A continuous at 24 VDC. This power supply also is equipped with thermal overload and short circuit protection with auto reset and PTC battery protection. For more information, go to: http://bit.ly/2abwhhx.

SDC (Security Door Controls), Camarillo CA: The model12VR access control power supply provides a 12VDC regulated and filtered output. With the power supply output set at 24VDC for locking devices and components, the addition of the 12VR provides a separate 12VDC, 500 mA output for 12V access controls and components. The total load of both outputs combined may not exceed 1A, 500mA at 12VDC. For more information, go to; http://bit.ly/2acvdN1.  

Securitron, Sparks, NV: The model AQD6 AccuPower® power supply, which provides 6 Amps of field-selectable 12 or 24 Volt output, is designed to power sensitive DC-based access control devices and sensors. It features a dedicated battery charging circuit that provides tight control of the 24V output while still charging the batteries with 27 Volts. The AQD6 is up to 90 percent efficient so it emits less heat, thus reducing energy consumption and lowering air conditioning requirements in server rooms. The AQD6 meets UL 294 6th Edition and is backed by the Securitron MagnaCare® lifetime, no-fault replacement warranty. For more information, go to www.securitron.com.

Sielox LLC, Runnemede, NJ: The new SLX Power Supply series is modular, expandable, and designed to mount on a wall or in an equipment rack with or without PoE (power over Ethernet).  Enhanced features include battery and system health monitoring, web monitoring reporting, and system control. The Sielox intelligent power supply offers dual-voltage operation, providing a set voltage of 24VDC and with the B100 module, 12VDC. This power supply comes with eight auxiliary programmable outputs and includes a locking cabinet. For more information, go to: http://bit.ly/2aeQLcX.