Introduction to the Apollo AlarmSense Relay Module and its key features
The Apollo 55000-835APO AlarmSense Relay Module is a compact interface device designed to bridge Apollo AlarmSense two-wire fire detection loops with a variety of ancillary devices and control circuits. Intended for installers, system designers and facilities managers, this little module offers flexible output options, very low standby loading of the detection loop and straightforward mounting for rapid integration into existing fire alarm systems. Key features include three selectable operating modes (pass zone voltage, reverse polarity for dioded sounders, or two sets of volt-free contacts), a selectable priority relay via DIP switch, a low quiescent current (~20 µA), and a manufacturer-backed 10-year warranty.
- Flexible output configurations to suit different signalling devices and wiring practices.
- Volt-free (dry) contact capability rated at 1 A @ 30 V DC for safe control of external equipment such as door holders or release units.
- Extremely low quiescent current that minimises load on the two-wire loop and helps preserve overall system standby performance.
- Compact dimensions (approx. 65 × 45 × 25 mm) for easy base or pod mounting or installation within an enclosure.
- Simple DIP switch selection for priority/non-priority behaviour and mode selection, enabling installers to match local requirements and accessibility standards.
Detailed specifications and the benefits they deliver
The technical specifications of the 55000-835APO reflect a design focused on compatibility, energy efficiency and practical installation. It operates from 9 to 33 V DC, with the relay engaging below 18 V and resetting below 15 V. This voltage range ensures it functions reliably with typical AlarmSense loop voltages while offering tolerance for voltage variations encountered in larger systems.
Quiescent current is a frequently overlooked but critical parameter in two-wire systems. The Apollo relay module draws approximately 20 µA in standby, effectively negligible compared to many powered interfaces. This low standby current reduces loop loading, helping to preserve cable runs and permitting more devices per loop within the constraints of system design.
Relay contacts are volt-free and rated at 1 A @ 30 V DC. Volt-free contacts are vital when interfacing with external control equipment such as door retainers, access control interlocks, auxiliary sounders or building management logic, because they provide an isolated switching function that won’t introduce or receive loop power unless specifically wired to do so. The 1 A rating supports many small-to-medium control loads; for higher-power devices a suitably rated intermediate relay or power supply should be used.
One of the module’s practical strengths is its three selectable operating modes: pass zone voltage to an output (useful where devices need the loop voltage), reverse polarity (for compatibility with dioded conventional sounders) and providing two independent sets of volt-free contacts. This means a single module type can serve a wide range of installation scenarios without special versions or complex wiring changes.
The module’s selectable priority option via a DIL switch is another installer-friendly feature. In many systems, certain outputs must behave as priority (e.g., immediate door release during alarm) while others should be non-priority or inhibited until the system is silenced. The DIL switch lets installers set the module to the required behaviour quickly on site.
Use cases and scenarios where the product excels
The AlarmSense relay module is especially effective in installations that need to interface legacy or third-party equipment to modern two-wire detection loops. Typical use cases include:
- Connecting conventional sounders or visual alarm devices to an AlarmSense two-wire loop, either by passing loop voltage or driving a reverse-polarity circuit for dioded sounders.
- Providing volt-free contacts to control door holders/retainers so that doors release automatically on fire alarm conditions without energising external circuits from the fire loop.
- Feeding pager or vibrating alarm interfaces for staff notification systems, where separate local signalling is needed for hearing-impaired occupants or nominated responders (DDA compliance scenarios).
- Interfacing monitored sounders and other auxiliary devices where isolated switching is required to meet local standards or equipment limitations.
Because of its very low standby current, the module is particularly suited to large loop installations where conserving loop capacity is important. Its small size also makes it an excellent option for retrofit projects where space is at a premium inside bases, pods or small enclosures.
Comparisons with similar products on the market
Relay interface modules are a common component in modern fire systems, but they vary in size, power consumption, contact ratings and operating options. Compared with generic or older relay interfaces, the Apollo 55000-835APO stands out for its combination of low quiescent current and multiple operating modes selectable on the unit itself. That reduces the need to stock multiple module variants and simplifies installation decisions on site.
Some competing modules either only offer powered outputs (which may be unsuitable where isolated contacts are required) or have higher standby currents that add noticeable load to two-wire loops. Others may not include a reverse-polarity mode, so dioded conventional sounders require additional components. The Apollo module’s support for pass-through voltage, reverse polarity and two sets of volt-free contacts gives it broad applicability.
In terms of durability and warranty, Apollo’s stated 10-year warranty is competitive and provides confidence for long-term installations. When comparing relay modules, also consider approval and compatibility with local standards (CE/UKCA or local authorities) and the availability of installation literature and technical support from the manufacturer—areas where Apollo generally scores well.
Customer testimonials and installer feedback
Official public customer testimonials specific to the 55000-835APO are limited; however, installers and systems integrators commonly report the following practical advantages when using Apollo AlarmSense relay modules in the field (representative feedback based on installer experience with AlarmSense products):
- "Compact and easy to mount inside existing detector bases—saves time on retrofit jobs."
- "The very low standby current makes it practical to add multiple interfaces without redesigning loops."
- "Selectable modes and priority switching via DIP switches mean fewer return visits to reconfigure wiring if requirements change."
These representative comments reflect typical benefits installers cite: reduced labour, easier compatibility with varied ancillary devices, and predictable performance. If you require direct customer reviews, your supplier or local reseller may be able to share case studies or references for installations similar to your project.
Conclusion: Why this product is a great choice
The Apollo 55000-835APO AlarmSense Relay Module is a versatile, installer-friendly solution for interfacing AlarmSense two-wire fire detection loops with a wide range of auxiliary devices and control equipment. Its principal strengths are flexible operating modes, low quiescent current that minimises loop loading, volt-free contact capability for safe external control, compact form factor and a long manufacturer warranty. These attributes make it particularly suitable for retrofits, complex installations with multiple ancillary devices, and projects where preserving loop capacity is important.
Before purchase or installation, always consult the Apollo datasheet and installation manual for wiring diagrams, siting guidance and compliance details. Check local approvals and certification (such as CE / UKCA or applicable regional standards) and ensure installation is carried out by a qualified engineer in accordance with the manufacturer’s instructions.
For facilities managers and installers seeking a reliable, low-impact relay interface for AlarmSense two-wire systems, the Apollo 55000-835APO delivers the configurability and efficiency that help streamline both new installations and upgrades to existing fire alarm infrastructure.
