Altronix WGI Wireless Mesh Gateway for Fire Alarm and Life Safety Systems
Overview
The Altronix WGI is a 902-928 MHz wireless mesh gateway engineered for fire alarm and life safety installations where pulling wire to every device is impractical or cost-prohibitive. Each WGI manages up to 49 wireless field devices on a single gateway — and the system scales to four gateways operating simultaneously, giving you a total supervised mesh of up to 196 field nodes without adding panel slots. If you're commissioning a retrofit across a historic building, a multi-tenant campus, or a warehouse where conduit runs would be destructive or simply uneconomical, the WGI is worth a close look as part of the Altronix wireless life safety line.
The unit draws 40 mA max at 24VDC from an external supply (18-30VDC range), or 24 mA when powered directly off a Signaling Line Circuit — that SLC compatibility at 15-30VDC is the integration detail that makes this work cleanly with conventional and addressable fire alarm panels without a dedicated power homerun to every gateway location. Physical footprint is compact: 1 7/8" tall, 7 7/8" diameter, sized to drop into a standard electrical box or panel knockout.
Key Features
- 902-928 MHz Mesh Radio: Operating in the 900 MHz ISM band gives this gateway better wall and floor penetration than 2.4 GHz alternatives — critical in concrete-heavy commercial and industrial structures where Wi-Fi-band devices lose signal rapidly across floor plates. FCC ID PV3WFSGW confirms the radio is certified for unlicensed US operation.
- 49-Device Gateway Capacity: A single WGI supervises up to 49 wireless field devices. For most mid-size floor plates that's sufficient end-to-end coverage from one gateway, reducing the number of supervised network nodes you need to manage on the panel side.
- 4-Gateway Scalability: Up to four WGI gateways can operate together in a single system, scaling total device count to 196 supervised wireless endpoints — enough for large multi-floor or campus deployments without switching to a different product family.
- SLC Loop Power Compatibility (15-30VDC, 24 mA max): Powering the gateway directly from the panel's Signaling Line Circuit eliminates the need for a local 24VDC supply at every gateway location. At 24 mA max draw, you're adding a predictable, low-burden load to the SLC — calculate your loop resistance budget against the 50-ohm max SLC resistance spec before finalizing wire runs.
- Dual Power Input (18-30VDC External or SLC): The external supply option (18-30VDC, 40 mA max) provides flexibility where SLC power isn't available or where loop loading is already tight. Having both paths means you can standardize on one installation approach per project rather than designing workarounds.
- RF Noise Floor and Signal Margin Specs (-85 dBm noise floor, -55 dBm min signal): Published RF thresholds give you a real commissioning target. The 30 dB margin between noise floor and minimum signal strength is a useful site-survey benchmark — if your RF scan shows ambient noise approaching -55 dBm in a location, that gateway placement needs to move before you close the ceiling.
- +17 dBm Max RF Output: Transmit power of +17 dBm (approximately 50 mW) balances range with co-channel interference management — enough output for typical commercial floor plates without creating interference patterns that degrade neighboring mesh nodes.
- UL S3511 and CSFM 7300-0559:0510 Listings: UL S3511 covers wireless systems for fire alarm service — this listing is what your AHJ will ask for on permitted work. CSFM listing 7300-0559:0510 clears California installations. Confirm with your local AHJ whether additional state or municipal listings apply before specifying.
- Operating Range 32°F to 120°F, 10-93% RH Non-Condensing: The temperature and humidity envelope covers most occupied commercial and light-industrial interiors. If you're installing in an unconditioned space — loading dock, parking structure, exterior-adjacent mechanical room — verify ambient conditions stay within this range year-round before specifying.
Integration and Compatibility
The WGI connects to fire alarm panels via the Signaling Line Circuit or via a dedicated 18-30VDC supply, making it compatible with a broad range of conventional and addressable fire alarm control panels that support SLC device addressing. The max SLC resistance of 50 ohms sets a firm wiring constraint: calculate total loop resistance including all wire runs and device terminations before finalizing your design. For multi-gateway deployments, all four WGI units share the same mesh frequency band (902-928 MHz), so site survey and channel planning are necessary steps — particularly in dense RF environments like hospitals or high-rise office buildings where multiple systems may share the ISM band.
The compact 7 7/8" diameter form factor fits standard electrical enclosures, and the low current draw on both power paths keeps the load impact on panel power supplies minimal. For system design guidance on wireless fire alarm architectures and device placement best practices, review the wireless fire alarm systems category alongside current NFPA 72 requirements for wireless node placement and supervision intervals.
Frequently Asked Questions
Q: How many wireless devices can one Altronix WGI gateway support?
A: Each WGI supports up to 49 wireless field devices per gateway. The system accommodates up to 4 gateways simultaneously, for a maximum of 196 supervised wireless devices across the full installation.
Q: Can the WGI be powered directly from a fire alarm panel's Signaling Line Circuit?
A: Yes. The WGI accepts SLC power in the 15-30VDC range and draws a maximum of 24 mA from the loop. You must verify that total SLC loop resistance does not exceed the 50-ohm maximum resistance specification before finalizing wiring.
Q: What frequency band does the WGI use, and is it FCC certified?
A: The WGI operates in the 902-928 MHz ISM band. It carries FCC ID PV3WFSGW, confirming it is certified for unlicensed operation in the United States.
Q: Is the WGI UL listed for fire alarm use?
A: Yes. The WGI carries UL listing S3511, which covers wireless systems for fire alarm service, and CSFM listing 7300-0559:0510, which clears California State Fire Marshal requirements. Always confirm with your local Authority Having Jurisdiction whether additional listings are required for your jurisdiction.
Q: What are the environmental operating limits for the WGI?
A: The WGI is rated for operating temperatures of 32°F to 120°F (0°C to 49°C) and relative humidity of 10% to 93% non-condensing. It is not rated for outdoor or unconditioned space installations where these limits may be exceeded.
Q: What is the minimum signal strength required for reliable mesh communication?
A: The WGI requires a minimum received signal strength of -55 dBm, against a maximum ambient noise floor of -85 dBm. This 30 dB margin should be used as the benchmark target during RF site surveys and gateway placement planning.
The WGI sits at the intersection of fire alarm compliance and wireless infrastructure — and the spec that most integrators should be anchoring their site survey to is the -55 dBm minimum signal requirement. In my experience designing wireless life safety systems, that 30 dB link margin above the -85 dBm noise floor sounds comfortable until you're in a steel-framed building with active HVAC and neighboring 900 MHz submetering systems eating into your margin. Plan conservatively, not optimistically.
Technical Highlights:
- SLC Loop Power (15-30VDC, 24 mA max): At 24 mA max draw, the WGI adds a very modest load to most panel SLC loops — but the hard 50-ohm max resistance spec means long wire runs on thin conductors can disqualify an otherwise clean gateway placement. Do the resistance math before you commit to conduit routing.
- 902-928 MHz Band Selection: The choice of 900 MHz over 2.4 GHz is deliberate and correct for life safety applications — lower frequency means better building penetration per watt of transmit power, and the +17 dBm output at 900 MHz delivers effective range in multi-story concrete structures where 2.4 GHz mesh would require far denser gateway placement.
- 4-Gateway System Scaling: The 4-gateway ceiling (196 total supervised devices) is the right design scope for mid-size facilities — a single-building hospital wing, a multi-tenant mid-rise floor, a large warehouse. Beyond that, you're looking at a different product architecture entirely, so size your system headroom accordingly during design.
Deployment Considerations:
- CSFM listing 7300-0559:0510 covers California, but always pull the current AHJ acceptance list for your jurisdiction — some municipal fire authorities maintain their own approved-device lists that may supplement or supersede state listings.
- The 32°F lower temperature limit is a real constraint: mechanical rooms, parking structures, and any space that drops below freezing in winter are out of scope. Verify HVAC setpoints and building envelope conditions before placing gateways in perimeter spaces.
For historic building retrofits, tenant improvement projects in occupied high-rises, or any situation where open-cut wire runs would trigger code reviews or aesthetic objections, the WGI is the product to specify — but it earns that spec only after a proper RF site survey validates your gateway placement against the -55 dBm minimum signal threshold.
