Specialty · Franklin County & St. Louis, MO
An automatic transfer switch (ATS) is what makes a standby generator actually automatic — it senses utility loss, starts the generator, transfers the load, and transfers back when utility power returns. CAS Electric installs and replaces ATS units across Franklin County and the Greater St. Louis area — Pacific, Washington, Union, Sullivan, St. Clair, Eureka, Wildwood, Villa Ridge, and Marthasville.
There are two main types of automatic transfer switches for residential and small commercial: service-entrance rated (SE-ATS), which sits between the meter and the panel and transfers your entire service, and load-side ATS, which sits between the main panel and a critical-loads sub-panel and only transfers a curated set of essential circuits.
Service-entrance ATS is the right choice for whole-home coverage when the generator is sized to run everything. It's simpler in some ways (no load-shedding logic) and gives you your whole house on backup power. Load-side ATS is the right choice when you want backup on essentials only — furnace, sump, fridge, some lights, maybe one A/C — and want to spec a smaller (cheaper) generator.
We install both types, coordinate the panel work (sometimes a new critical-loads sub-panel is part of the scope), and commission the ATS with simulated utility failures to verify transfer timing and correct behavior on return-to-utility. All work is permitted and inspected.
ATS install pricing depends on ATS type (service-entrance vs load-side), amperage, and whether a critical-loads sub-panel is part of scope. Full generator + ATS installs are quoted as a package. We provide a free written estimate.
We determine whether service-entrance or load-side ATS is the right fit and size the switch to your service.
Includes ATS, any critical-loads sub-panel, wiring, permit, and inspection coordination.
ATS mounted, wired between utility and panel, tied to generator start signal, and commissioned with simulated utility failures.
Local inspector signs off, we walk you through the ATS status indicators and manual override procedure.
An ATS transfers automatically without you touching anything. An interlock kit is a mechanical safety device that lets you manually flip your main breaker off and a generator inlet breaker on. Interlocks are cheaper but require you to be home during an outage to switch over.
Only with a load-side ATS. Service-entrance ATS transfers your whole house so no sub-panel is needed. Load-side ATS uses a separate critical-loads panel with just the circuits you want to keep running during an outage.
Depends on the generator. Manual-transfer-only generators can't be upgraded to automatic without changes on the generator side. Standby generators from Generac, Kohler, etc. that were installed with a manual switch can often be converted by swapping the manual switch for a compatible ATS.
Usually one day for the electrical work — pad, ATS mount, wiring between meter/panel and generator, commissioning. Inspection is scheduled for the same or next day.
Portable generators typically use manual transfer switches or interlock kits rather than automatic transfer switches. We install both — but true automatic transfer requires a standby generator.
Licensed, insured, owner-operated. We respond to all estimates within 1 business day.