Wheelock, now a brand under Eaton, has been a leading manufacturer of fire alarm notification appliances for decades. Their horn/strobe and strobe-only units are found in commercial buildings across the United States — and when it’s time to replace a failing unit or match existing devices in a renovation, getting the right Wheelock part matters. This guide covers the most common Wheelock notification appliance models, their specifications, replacement scenarios, and how to ensure wiring compatibility.
About Wheelock (Now Eaton)
Wheelock was acquired by Eaton Corporation and is now marketed under the Eaton Wheelock brand. Production of core product lines has continued under the new ownership, and most Wheelock model numbers remain the same. When sourcing replacements, you can use the original Wheelock part numbers — they’ll match up with current Eaton Wheelock catalog items.
Wheelock MT Series: Multi-Tone Horn/Strobe
The Wheelock MT series is one of the most widely deployed fire alarm notification appliances in commercial settings. The MT series includes both horn/strobe combos and strobe-only models.
Common MT series models:
- MT-12/24-WH — Multi-tone horn/strobe, white, 12/24V DC
- MT-24MCW-FR — Multi-tone horn/strobe, fire red, 24V DC
- MIZ-24 — Strobe-only model for visual notification only
- E50 — Horn-only model (for areas needing audible only)
MT series horn/strobes are wall-mounted and designed for indoor use. They support multiple tone settings (march time, temporal 3, and more) configurable via onboard jumpers or switches.
MT Series Key Specs:
- Operating voltage: 12V or 24V DC (model-dependent; most are 24V)
- Current draw: Typically 85–260 mA depending on strobe candela and tone setting
- Strobe intensity: Available in 15, 30, 75, 110 cd ratings
- Sound output: 85–99 dB(A) at 10 feet (tone-dependent)
- UL Listed: Yes (UL 1971 for visual; UL 464 for audible)
Wheelock AS Series: Architectural Horn/Strobe
The AS series (also called ADA series) is designed for applications requiring higher-candela output or architectural aesthetics. Common in lobbies, atriums, and open floor areas where longer throw distances are needed.
Common AS models:
- AS-241575W — 24V, 15/75 cd selectable, white
- AS-241575R — 24V, 15/75 cd selectable, red
- ASWP-2475W — Weatherproof outdoor model, white
The AS series features a sleek, lower-profile housing compared to the MT series and is frequently specified for renovation projects where visual uniformity matters.
Common Replacement Scenarios
The most frequent reasons to replace Wheelock notification appliances include:
- Strobe failure: The xenon flash tube burns out over time; the horn may still work but the strobe is dead — a code violation
- Horn failure: Corrosion, moisture intrusion, or component failure causes the horn to buzz, rattle, or go silent
- Physical damage: Impact damage, vandalism, or paint overspray requiring replacement
- Candela upgrade: Older 15 cd strobes may no longer meet ADA/NFPA 72 spacing requirements under current code — upgrading to 75 cd or 110 cd units
- Color mismatch: Building renovation requires matching new paint scheme — swapping red units for white or vice versa
Wiring Compatibility: What to Check
Before ordering replacement Wheelock devices, verify the following:
- Voltage: Most commercial systems are 24V DC NAC circuits; some older systems may be 12V
- Polarity: Wheelock devices are polarity-sensitive. Ensure proper polarity when wiring
- Current budget: Each NAC circuit has a maximum current rating. Adding higher-candela strobes increases current draw — recalculate your NAC budget
- Synchronization: Wheelock and other brands use different sync protocols. If mixing brands on the same NAC, use a Wheelock sync module to avoid strobe flicker issues
- Back box: Many Wheelock devices require a specific back box depth — verify before cutting new holes
Matching Existing Devices
When doing partial replacements (replacing only failed units), try to match the existing model number exactly for visual consistency and electrical compatibility. Check the label on the back of the device before removing it — Wheelock labels typically show the full model number, voltage, and candela rating.
If the exact model is discontinued, look for a direct successor in the current Eaton Wheelock catalog with matching form factor, voltage, and candela.
Where to Buy Wheelock Replacement Parts
Life Safety Consultants carries a wide selection of notification appliances, including Wheelock/Eaton horn/strobe units. Browse our full product catalog to search by model number, or explore replacement parts from all major brands in our fire alarm parts store. We ship throughout the US with fast fulfillment on in-stock items.
