100-400A residential and light-commercial ATS with 2-wire start compatibility. UL 1008 listed, 240V single-phase, true double-throw contacts. ASCO quality for home standby and small business backup.
The ASCO 185 Series is ASCO's residential and light-commercial automatic transfer switch, covering 100A through 400A at 240V single-phase. It brings ASCO's commercial switching heritage to the home standby market — true double-throw contacts with mechanical interlocking, the same fundamental switching mechanism used in ASCO's 300 and 7000 Series commercial lines.
The 185 uses standard 2-wire start control, making it compatible with any generator brand. When utility power is absent for 1 second or more, the ATS signals the generator to start. Transfer occurs automatically once the generator reaches rated voltage and frequency. An integrated exercise circuit tests the generator weekly under load or no-load, selectable by the installer.
The ATS amperage must match or exceed the main service panel amperage. Most Northern California residential installations use the 200A variant. The service-entrance rated 185SE version can serve as the main disconnect, simplifying the installation when the ATS is positioned at the utility service point.
NEMA 1 (indoor): Steel enclosure for utility rooms, garages, or basements
NEMA 3R (outdoor): Aluminum alloy enclosure rated for rain, sleet, and ice. Standard for residential generator installations where the ATS mounts outdoors near the meter and generator
The ASCO 185 is less common in our residential service territory than Kohler and Generac bundled switches, but when we encounter them, the quality is evident. The mechanical switching components are more robust than the residential switches from generator OEMs. The most common service call is exercise timer misconfiguration — installers sometimes set the weekly exercise without confirming the homeowner's preferred day and time. We also see occasional LED indicator board failures on units over 10 years old, which don't affect switching function but eliminate visual status feedback.
Frequently Asked Questions
What amperage range does the ASCO 185 come in?
100A through 400A in five sizes: 100A, 200A, 230A, 260A, and 400A. The 200A is the most common residential size, matching standard 200A service panels. The 230A and 260A are specialty ratings for heavy-use homes that exceed 200A but don't warrant a 400A service upgrade.
Is the ASCO 185 compatible with all generator brands?
Yes — the 185 Series uses standard 2-wire start signaling, which is universal across all major generator manufacturers (Kohler, Generac, Cummins, etc.). When utility power fails for 1 second or more, the switch signals the generator to start. Power is typically restored within 30 seconds.
Does the ASCO 185 come in a service-entrance rated version?
Yes — the 185SE variant is UL 1008 service-entrance rated, allowing it to serve as the main disconnect for the building. This eliminates a separate main breaker upstream and is common in new residential installations where the ATS is installed at the service entrance.
What enclosure options are available?
NEMA Type 1 (indoor, steel) and NEMA Type 3R (outdoor, aluminum). Both feature hinged doors. The 3R outdoor enclosure is the standard choice for residential installations where the ATS mounts near the generator and utility meter.
Why choose an ASCO 185 over the transfer switch bundled with my generator?
Generator-bundled switches are typically made by the generator manufacturer. The ASCO 185 brings ASCO's switching heritage and component quality to the residential market. The true double-throw contacts with mechanical interlocking are the same proven design used in ASCO's commercial lines. For homeowners who want commercial-grade reliability in a residential package, the 185 is the upgrade.
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