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Through the pages of Security Installer we have come to understand how networked access control systems together with IP links can provide enormous levels of manage-ment information and restrict movement within particular areas of remote complex sites.

However, in practical terms, this is all founded on more humble beginnings. Therefore perhaps we should now go back a stage to look at the basics of door entry and illustrate how a newcomer can actually make a start in this truly lucrative market.

Taking the first step
Access control is certainly a market that the engineer familiar with intruder alarms will always wish to operate in to some extent because, in theory, it is a natural progression.

Indeed, we are witnessing increased competition in the manufacture of integrated security control panels that feature not only zones for intruder, personal alarm and fire but now also include an ability to read a number of tags for access control functions. But it is easy for those engineers extending into access control to overlook some very basic needs that can ultimately prove costly and discredit otherwise highly respectable systems.

This applies to the most mainstream of door entry schemes based on intercoms and code locks. These are the starting points for intruder alarm engineers making casual inroads into access control. So, as a starter, let us consider safety-locking aspects and then overview electric locks before looking at where sales potential surely exists.

A safe direction
Always think in terms of safety because, even with the most basic network, once this is applied to control any door or barrier there are rules that must be adhered to. In every case there is a need for a lock to have a mechanical override to cater for an electrical control fault or failure of the power supply.

When installing an electrical lock ensure that when it has been automated: this is by an additional technique and the original mechanical function has not been removed or compromised. Therefore, even in the event of a residential door having an electrical lock installed, make sure that the lock retains its optional mechanical locking and manual override features.

Safety rules require that people must be able to leave an area safely, even though precautions have been made to make it difficult for entry to be granted. Legislation and building regulations influence emergency exiting in buildings open to the public but these can equally be applied to residential applications.

Always extend your thoughts to include the welfare of the infirm, the visually impaired and people in wheelchairs. Remember that fire doors can be degraded if the locking is modified as this can affect its fire resistance.

As a guide fire exits must be:

• Easily visible
  
• Simple to operate by one action
  
• Designed with minimum hardware and have only one opening device with a smooth surface
  
• Unlocked from the inside and be of fire rated material
  
• Fitted with an automatic door closer.

Locks … an art in themselves
Before starting any project be alert to the fact that the fitting of an alternative lock or the drilling of further holes in a door for the wires can invalidate a customer's guarantee on the door.

In practice the easiest method of installing any standard electric lock is to replace the existing lock striker plate with an electrically energised release. It allows the keep of the lock to rotate or swivel so that the fully extended lock can pass through the keep without the lock retracting.

This is the device supplied as a standard component with intercom kits and is time honoured, easily understood and used extensively for automating purposes. In operation, electromagnetic locks are rather different as they secure doors through magnetic force and always unlock when power is removed and then lock as the power is applied.

They are formed from two parts, namely an electromagnet and a locking armature. Therefore, by their very nature, they have no override but are a little more expensive than traditional electric locks. They form a good option on badly fitting or glass doors or those that only have small frames and can be used as an addition to any traditional locking system.

Electromagnets are 'continuously rated' as power to them must be available at all times other than when the device unlocks.

It should be noted that variant traditional electromechanical locks can also be purchased for continuously rated duty and for use in those applications demanding fail unlocked conditions as, in these cases, the lock will become unlocked in the event of power failure.

However for high security, all continuously rated locks should be supported by standby power or batteries in case of power supply failure.

Having come to understand the essentials of selecting and installing the electric lock it is then possible to look at those areas where the newcomer can find sales opportunities for both intercoms and code locks.

Intercoms and code locks
Without doubt, intruder alarms continue to form the nucleus of the electronic security systems industry but – rather like insurance – to many users, they form a grudge purchase.

Intercoms and code locks are somewhat different in that their use is more overt since they are seen to be in constant use. Although intercoms and code locks may use integrated techniques, for the purpose of this article we shall view them as separate identities.

The installing of intercoms is straightforward. They comprise of a door panel speech unit linked to an intercom (often a telephone handset) powered by a transformer or power supply and ultimately controlling the electric lock.

Code locks configured for standalone use are typically as Fig 1. They will have comfort LEDs for keypad feedback with auxiliary relays to indicate such functions as tamper, forced door, penalty count or door ajar. Alternatively the relay may be used to interface an intruder alarm.

Selecting the route forward
Door entry is a good starting point into access control as the wiring is not unlike intruder cabling, although voice circuits tend to use solid core conductors. In all cases, use the recommended cabling as specified by the manufacturer.

With intercoms the idea is to look for applications where doors can be unlocked from a remote point by the system subscribers once they have talked to, or actually seen, the proposed entrant to an area.

They have great potential and are an extension on the use of apartment block call systems. Intercoms are also ideal for elderly people and the infirm or those who do not have the ease of mobility or even the inclination to physically attend to all callers.

For more diverse installations think of any applications where a reception area may be some distance from the access point to the premises.

Code locks with PINs or an alphabetical code are ideal in keeping doors to sensitive areas locked without the inconvenience of having to carry keys. Always offer the advantages of electrically energised code locks over purely mechanical devices because they include circuits for monitoring of the door and allow alarm outputs to be generated, plus control circuits for exit buttons.

Once the installer has gained a foothold with code locks it is then possible to make an effective move into other access based solutions containing management techniques.

The normal selection process is to choose either an intercom or code lock and to then compile a checklist involving safety considerations and locking techniques. See Fig 2.

It becomes apparent that the newcomer must first identify the key components used in door entry systems and understand the basics of automating electrically locking doors and the safety issues that surround them. Having gained some experience it becomes possible to make inroads into those installations that include more complex access based solutions, hands free applications and IP management techniques. These later stages will also, of course, involve the automation of turnstiles and barriers to facilitate high volume people and traffic control with a need for additional safety measures.