TRIMEC

AC OR DC?

Where security is involved you cannot always expect a low cost AC strike to offer the same level of security that can be achieved by using a more expensive medium/high duty strike. Pick a product that is fit for the purpose. Short-term savings can work out very expensive. Most of the low cost door entry systems operate on AC rather than DC. Alternating Current produces the familiar buzzing sound which is not heard with DC systems, and AC strikes are only available as Fail Secure (Power to Open). More sophisticated systems operate on DC allowing for continuous silent Fail Open (Power to Lock) or Fail Secure (Power to Open) operation.

POWER SUPPLY UNITS

One of the most important areas for consideration when using any electric locking device is the PSU. Correct specification will help ensure fault-free running and ensures the PSU puts out the correct voltage required to run the electric strike within the tolerances stated. Remember to take into account any other products running off the same PSU. Most access control systems in the Australia run off 12v DC with the other common type being 24v DC.

Normally 24v DC runs at half the current draw of 12v DC which may be of assistance when working out what PSU to use. Most of the Australia fire alarm industry runs on 24v DC. If possible, ensure it is a regulated PSU whilst consideration should also be given to the gauge of wire used to supply the product. Long and thin wire runs could lead to voltage drop at the product and further problems.

DEVELOPMENTS

These have included higher holding forces; rapid Power to Lock/Power to Open and vice versa changeover; more shallow overall depth reducing frame cut-outs and possible weakness; rebated face plates for timber doors; low current consumption; low heat generating solenoids; cast one-piece bodies; supplying templates to assist fitting; weather resistant models and extended warranties. Three companies now offer UL rating, with one offering both UL and CE approval.

An area of concern is fitting electric strikes to outward opening doors. Potentially doors fitted with standard ANSI strikes are left vulnerable because of the open lead-in extension lip, often unavoidable on aluminium door applications.

This led to the development of lipless and wrap-around strikes now available from a number of manufacturers which, when used in conjunction with an integral door or face fix T bar, offer the highest levels of security attainable with an electric strike.

Electric strikes are not the all-encompassing solution for all problems - like all things in life the right product still needs to be correctly specified and installed in the right place, and all reputable manufacturers will give guidance to help the installer make the right choice.