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ML20A Restricted Key System for Construction Sites in Auburn

Macquarie Locksmiths supplied and configured 100 commercial-grade padlocks into an ML20A restricted key system for a construction company operating 5 new sites in Auburn. Each site received 20 padlocks keyed to a site-specific restricted key, with a single master key operating all 100 padlocks across every location. Keys cut to the ML20A restricted profile cannot be duplicated at any standard key cutting outlet. Additional keys require written authorisation from the registered signatory and are produced through Macquarie Locksmiths only.

What was the problem?

A construction company opening 5 new sites in Auburn needed gates and doors secured at each location, with a keying arrangement that gave management access to all sites while preventing workers from duplicating their keys at a hardware store or key cutting outlet.

Standard padlocks with unrestricted key profiles were not an option. Keys cut to a common profile can be duplicated at any locksmith or hardware retailer without the property owner's knowledge. On an active construction site with multiple workers and rotating staff, that removes all control over who holds a working key.

What did we find on site?

All 5 sites were newly established with no existing security hardware fitted. Gates and door access points across every location needed padlocks from day one, and the keying structure had to separate worker access by site while keeping a single point of master access for management.

A flat keying arrangement — one key type operating all 100 padlocks — was ruled out immediately. It would give every worker access to every site and leave the client with no practical way to limit key copies or audit who held a working key to each location.

What did we install?

We supplied 100 commercial-grade padlocks and installed ML20A restricted cylinders into each one. The ML20A uses a 6-pin inline restricted key profile, which prevents duplication at any standard key cutting outlet. Each of the 5 sites received 20 padlocks, keyed into a two-tier access hierarchy: a site-specific restricted key for workers and a master key operating all 100 padlocks across all 5 sites.

The access hierarchy was registered through Macquarie Locksmiths' restricted system. Two key types were issued at the time of installation: site-specific restricted keys, which operate only the 20 padlocks at the assigned site, and one master key held by the client's nominated signatory, which operates every padlock across all 5 locations. Commercial-grade padlocks carry a higher shackle hardness rating than consumer-grade hardware, rated to resist physical attack on an unsecured construction site.

Why did we choose this solution?

The ML20A restricted key system was selected because it gives the client direct, registered control over key production. No additional keys can be cut without written authorisation from the signatory registered to the system. Workers hold a site-specific key; they cannot access other sites or have copies made independently.

The master key structure suits a 5-site operation. Management carries one key covering all 100 padlocks rather than a separate key for each location. The restricted system registration also creates a documented record of every key issued, which is useful when staff leave or site access changes. Any future keys require the client's written authorisation and are produced through Macquarie Locksmiths, keeping the authorisation chain intact. Jobs like this fall under our commercial locksmith services, which include system design, keying schedules, and ongoing key management for businesses operating across multiple access points.

What was the result?

The construction company secured all 5 Auburn sites from day one with 100 commercial-grade padlocks fitted with ML20A restricted cylinders. Management holds one master key covering every padlock across all 5 sites. Workers at each site hold a site-specific restricted key operating only the 20 padlocks at their assigned location.

Key duplication outside the registered system is not possible. Every additional key requires written authorisation from the client's signatory and is produced through Macquarie Locksmiths. The client holds a verifiable record of every key in circulation across all 5 sites, with full control over who gains access at each location as the project progresses.

Job Photos
Restricted padlocks 1 Macquarie Locksmiths

Restricted padlocks 2 Macquarie Locksmiths

Restricted padlocks 3 Macquarie Locksmiths

Restricted padlocks 4 Macquarie Locksmiths

Restricted padlocks 5 Macquarie Locksmiths

About the site

Auburn sits within the Cumberland LGA, one of the highest-growth construction corridors in western Sydney. Development activity in the area spans residential apartments, light industrial fit-outs, and mixed-use projects, which means construction companies operating here frequently manage multiple active sites simultaneously across Auburn, Granville, and Merryweather.

Active construction sites carry a specific key control risk. Workers rotate between trades and subcontractors, site access changes as stages progress, and standard padlocks with unrestricted key profiles can be copied at any hardware outlet within walking distance. For a company running 5 simultaneous sites in this environment, an ML20A restricted key system with a documented authorisation chain is the practical standard, not an upgrade.

Need a restricted key system for your construction sites?

Construction companies and property developers managing multiple active sites across greater Sydney use ML20A restricted key systems to control who holds a working key at each location and prevent duplication outside the registered authorisation chain. Macquarie Locksmiths designs the keying matrix, supplies and fits the cylinders, registers the restricted system, and issues all keys with a documented authorisation record from day one.

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