In my 17 years of doing security systems, I see one prevailing problem: People decide to cut corners during installation. Security requirements are no different than any other electrical systemfail to follow the basic rules and the results could be shocking.
Throughout most of the United States, no uniform code enforcement or inspection of self-storage security systems is required. But general practices need to be followed to ensure owning a system that works with minimal problems. For the most part, these procedures are the same as the National Electrical Code with the exception that the security industry deals with low-voltage connections. Low voltage is defined as being below 50 volts. Security systems are usually either 12 volts or 24 volts. Following is a list of rules to follow when installing a security system.
Rule No. 1: From the Ground
All underground electrical wiring, including low voltage, should be installed only in PVC conduit. Electrical conduit is gray and can be bought at most hardware stores. Electrical fittings ensure the wire is not damaged during installation. Underground conduit runs should be buried at least 12 inches below grade, and all joints attached with PVC glue. Dont cut corners. Saving a few hundred dollars on a large project is pennies compared to the overall cost of the project, and will only set you up for later problems.
In most cases your electrician is digging his trenches to the same places your conduit needs to go. You can share his trench or even have him install your underground conduits. As a general rule, we have the electrician do the job for two reasons: Its more cost effective for the customer, and it keeps us (and them) from cutting other conduit runs. If opting to share a trench, remember to separate the conduit runs by 12 inches. This eliminates the bleed through between high and low voltages that can cause noise in your data runs. Skip this step, and the problem wont be correctable without separating the lines after the fact. Not a good problem to have.
Rule No. 2: Conduit Concerns
Above-ground conduit should be metal. PVC should extend between 6 and 12 inches above the ground before changing from plastic to metal. Never install a PVC-to-metal fitting at or below ground level. Doing so will allow water to seep into the conduit and hinder repairs. In some cases, larger sizes of conduit (2 inches and greater) can be run if placed at least one foot above grade. Check your local codes before doing this.
Metal-conduit fittings are designed as outdoor and indoor types. While outdoor fittings can be used inside, dont expose the inside variety to the elements, or water could enter the conduit runs. Not only does this increase the danger of shorts, it can compromise your system. Wires exposed to water will deteriorate and require replacement. Water exposure can also affect hardware and add to repair costs. The same is true for junction boxes. Only use outdoor-rated boxes outside. Install a pull or junction box every 150 feet on long runs to prevent overstressing wires when pulled longer distances. Overstressed wires may perform poorly.
Metal conduit should be fastened and supported. When possible, position it to eliminate the risk of damage from vehicles. Be sure to select the correct metal conduit. The two types are EMT and rigid. EMT can be used in most cases but sometimes rigid conduit is required, such as when vehicle traffic is a hazard. Flex conduit or connectors are required when connecting to moving or vibrating items like gate operators. Use a bender for turns rather than 90-degree fittings. This permits faster installation and lowers stress on the wire.
Rule No. 3: Size Matters
Undersized conduit runs and junction boxes will only make the job harder if not impossible. There are National Electric Code requirements for the number of conductors and the allowable size of conduit. The guidelines are to ensure enough heat dissipates when installing high-voltage lines. While this is not generally a problem with low-voltage lines, sizing the conduit is still a concern. I recommend 2-inch conduit runs between office, buildings and gate operator. From the gate operator to the keypads, it should be no less than 3/4 inch. This size will meet the installation needs of most systems, including cameras, alarms and intercoms. If you have a large site or plan to expand, two 2- inch conduits are suggested. If youre not installing a security system now, install the conduit anyway. Its cheaper to do it during construction, remodeling or driveway repairs than any other time.
Be sure to cap all conduits during construction. Unused runs should remain capped until needed. Leaving a conduit exposed to the elements for only a short time can render it useless. Dirt, water, rocks, concrete, mortar, etc., will find their way into an unprotected conduit. Always use a proper cap.
Rule No. 4: No, Really, Size Does Matter
Wire is the lifeline of a security system, allowing devices to connect and talk with each other and us to communicate with the system. Use the wrong kind of wire for the wrong application and your system wont perform correctly, if at all.
There are thousands of wire types, sizes and designations, governed by complex guidelines. Wire size determines how much electricity can flow from your power supply to the devices. This is called resistance, and the longer the wire run, the more resistance and lower voltage at the other end. To compensate for this drop in voltage, we increase wire size from the power supply to the devices.
Wire sizes are measured in numbers or gauges such as 8, 12, 14, 18, 22, etc. The bigger the wire size, the lower the number. For instance No. 14, or 14 gauge, is about 3/16 inch in diameter, while No. 6, or 6 gauge, is about 3/8 inches in diameter. The larger the wire, the less resistance and lower drop in voltage. Most systems can be installed using No. 14 or smaller wire.
Security wires or cables are designated using two numbers. The first number is the size. The second is the number of conductors or wires inside the cable. A cable marked 18/4 would be No. 18 (18 gauge) with four separate conductors. You need to know the total number of conductors required for your system to determine the correct wire.
Generally, one wire cant be run for all applications at your site. For a typical access system, a separate wire is needed for the keypad data, intercom, camera, power and to trigger the gate. In some cases, combinations of wires in one cable can be used, but combining the wrong applications can cause operational problems or void your equipment warranty.
Rule No. 5: Get Wired
There are also different wire types. Some wire is shielded with a foil wrap between the conductors and the outer jacket of the cable. This adds to the reduction of noise (see No. 1) that may plague data lines. This doesnt eliminate the necessity to separate high- and low-voltage lines. Shielding only helps reduce other noise problems. Some equipment requires shielded wire while others take non-shielded.
Camera systems require RG-59 cable, not RG-6. You can tell the difference by looking at the shield or braid. If the braid is aluminum, the wire is RG-6. If the braid is copper then the cable is RG-59. Using RG-6 on a camera system can result in ghosting on your monitor. RG-6 is used for cable TV.
Cameras also require a power cable. Use the correct gauge wire for this because too small of a wire will overload the power supply, sparking power outages and camera failure.
When installing an intercom system, be especially careful of what wire you use, where you place it and what is in the general area. Intercoms pick up more interference or noise than any other device. High-line wire across the street can cause static in the intercom. The same is true for lights in hallways. Some vendors suggest using shielded wire to compensate for this; however, its sometimes impossible to eliminate all static from the system. Use every precaution and be sure to consult your supplier for recommendations.
When making wire connections, depend on the proper items. Use wire nuts to join wires. Installing a wire under a screw on a terminal strip? Select wire connectors, such as spade connectors. These ensure the connection remains tight and no whiskers (small strands of wire) can come in contact with other wires, causing a short.
Rule No. 6: Simple Little Things
That old saying, If its worth doing, its worth doing right, perfectly applies to installing a security system. Many times, I have driven hundreds of miles to spend a few minutes fixing a system that needed a couple connectors or wire nuts. The owner could have avoided a hefty bill on the service call.
When dealing with electricity, you have to be proactive. You cant see it, smell it or hear it until its too latefar too late, in most cases. While you probably wont get hurt dealing with 12- and 24-volt systems, you can make a major hole in your bank account by simply not taking the time to use the right parts and equipment for the job.
Chester A. Gilliam works for Centennial, Colo.-based Wizard Works Security Systems Inc. and has been involved with self-storage security systems for the past 19 years. For more information, call 303.798.5337; e-mail [email protected].
For more information about self-storage security, check out "Security: Choosing Tools, Protecting Your Investment," a 32-page e-book available through the Self-Storage Training Insititute. Click here for more info!