How Many Doors Can an Access Controller Handle? 1, 2, 4 and Multi-Door Systems

Access controller capacity is more than the number of relays on a board. Door count, reader count, inputs, power and software limits need to support the intended opening arrangement together. NZ installers should build a door schedule first, then select controllers and expansion hardware against that schedule.

Define what counts as a door

For each opening, state whether entry only or both directions need credentials, and how the lock, door contact and exit request operate. A door with two readers consumes more interfaces than an entry-only arrangement, even if both use one lock. Special applications such as turnstiles and lift permissions also need a separate capacity review. Do not translate every reader or relay into one identical door.

Check supported reader arrangements

Verify the controller's reader ports, supported protocols and exit-reader expansion options. Confirm whether using an additional reader changes the supported door configuration. The Essential Security Supplies RBH-IRC-2000 listing identifies a two-door candidate, while the RBH-EXITRDR listing describes a particular exit-reader module. Use current RBH documentation to confirm the exact pairing and revision. A generic reader interface is not evidence that every credential format is supported.

Count the complete input and output requirement

Allocate contacts, request-to-exit inputs, tamper and relevant auxiliary signals before using spare interfaces elsewhere. Record lock relay ratings and any external relay requirement. A controller may have additional I/O while its supported door logic remains limited. Conversely, a software door licence does not add physical reader ports. Keep the hardware map and software schedule separate so both can be checked.

Check power and cabinet space

Confirm the controller's own supply and the separate connected-device load. A PoE-capable controller is not automatically able to power every proposed lock through the available PoE budget. Verify the permitted architecture and backup requirements. Leave practical wiring and battery space. A controller that fits the nominal door count can still be the wrong choice if its cabinet or power arrangement cannot serve the opening schedule.

Plan expansion and offline operation

List the actual future openings and their likely reader arrangement instead of buying vague spare capacity. Check bus limits, address space, network paths and licences for the expansion. Determine which decisions remain local during communication loss and what event capacity exists in the selected controller. Record the intended update and revocation behaviour. Capacity planning should include operation and support, not just initial connection.

Use a configuration matrix before ordering

Build rows for door, reader ports, I/O, supply, expansion and licence. Assign every planned opening to a supported configuration and identify unused capacity explicitly. For mixed controller families, confirm platform compatibility rather than assuming one brand name settles it. Trial a representative two-reader door before repeating it across the site. Keep the exact model and revision in the as-built register.

Apply the design to the actual project

Make the capacity review auditable by drawing one representative opening for every configuration used. Show reader ports, inputs, relays and the connected power arrangement. Mark any expansion board by exact model and revision. If a reader on each side changes the supported allocation, capture that clearly. Apply the configuration to the full door list and count remaining capacity only after every real opening is assigned.

Test the configuration with the intended software edition before repeating it across the site. Check reader events, contact state, exit requests and lock operation, then confirm the display and audit record. Review power limits with the connected hardware rather than the controller alone. Keep an expansion plan for specifically identified future doors and verify the communication and licence implications. A spare relay is useful only if the platform supports the intended additional function, and a spare software licence is useful only if suitable hardware can be connected.

Calculate power and prove operation during outages

Make a load schedule using the manufacturer's current figures for each lock, reader, controller and accessory. Separate continuous load from momentary or motor starting load. Check what happens when several openings operate together and when batteries recharge after a mains outage. Measure voltage at the furthest device under the worst intended load, because adequate voltage at the cabinet does not prove adequate voltage at the lock. Cable resistance, protection and connection quality all affect the result.

Agree the required behaviour for mains failure, controller communication loss and loss of the management server. Test these conditions safely under the commissioning plan and record which functions remain local and which depend on a server or external service. A cached credential might remain usable while a new revocation has not yet reached the controller. Recovery therefore needs a test of restored communication and database synchronisation as well as a simple successful door opening.

Commissioning acceptance checklist

Agree the expected result before testing. Use the installed configuration and retain evidence of each outcome, including a failure that must be corrected. The following checks supplement the exact manufacturer procedures and the approved project design.

Repeat affected checks after a material equipment, software or site change. Keep the test record with the as-built schedule so the next maintainer can understand which configuration passed and which assumptions still need review.

Equipment candidates and specification checks

These are relevant active catalogue candidates for a project review, rather than a universal recommendation or a promise of immediate stock. Use the full product page and current manufacturer information to confirm the supplied variant and its role in your design.

• RBH-IRC-2000 - RBH Integra32 2-Door Controller (UL Listed) includes Enclosure with 13.8VDC, 2A power supply. Confirm the exact supplied configuration, relevant interfaces and installation requirements before including it in the equipment schedule.
• RBH-EXITRDR - RBH Exit Reader Module-URC, IRC (Ver4+) & UNC (INT). Confirm the exact supplied configuration, relevant interfaces and installation requirements before including it in the equipment schedule.
• RBH-INT-UNC100 - RBH Integra CERTIFIED UNC100, 2 door PoE controller with enclosure & 13.8VDC 2A power supply. Confirm the exact supplied configuration, relevant interfaces and installation requirements before including it in the equipment schedule.

Review the relevant Essential Security Supplies equipment range alongside the intended workflow. For further context, read our related installer guide.

Frequently asked questions

Does a four-reader controller always control four doors?

No. Reader and door counts depend on the supported opening configuration.

Can software licences add physical ports?

No. Physical capacity and licensed capacity are separate limits.

Does PoE capability guarantee enough lock power?

No. Check the exact controller, PoE class, connected loads and supported power design.

Primary references and technical scope

Use the primary manufacturer or technical reference for the claims it covers. General design guidance does not replace the selected product's installation manual. Confirm current firmware, model variants and the approved project requirements before ordering or commissioning.

Get specification help from Essential Security Supplies

Send your site layout, equipment schedule, intended workflow and any existing model details to Essential Security Supplies for specification help and a project quotation. Identify the functions that must be demonstrated and the interfaces owned by other contractors. Our enquiry route supports a documented equipment review without publishing prices or assuming unverified compatibility.