The 100 Amp Transfer Switch RXSM100A3 from Honeywell International Inc. - smart backup for 24 kW home generators

Reviewed: ad hoc news Bestseller & Flagship desk. Edited and checked on 2026-06-29, 04:46. Details in the imprint.

The 100 Amp Transfer Switch RXSM100A3 from Honeywell International Inc. sits on the outside wall, a grey metal box you notice only when the lights go out and the generator hums to life. You hear the quiet click as it hands your house over to backup power, without fumbling for manual breakers.

What this switch really does

The RXSM100A3 is a single-phase, 240 volt automatic transfer switch rated for service entrance use, built to work with Honeywell home standby generators up to 24,000 watts. It monitors the utility line and, when the grid fails, quickly routes power from the generator to the home circuits.

In practice it behaves like a traffic cop for electricity. One moment your lights and fridge run on the grid, the next the switch flips control to the generator without you needing to step outside in the rain or in the dark. That hands-off behavior is why many installers treat it as a core part of a modern backup setup.

Designed around the 24 kW class

Honeywell targets this 100 amp switch at homeowners who pair a mid-size 24 kW generator with typical North American single-family loads, from HVAC to well pumps. The rating means it can serve as the main service disconnect for many homes, simplifying the panel layout.

Electricians like that the enclosure uses a NEMA 3R outdoor rating with a straightforward hinged door, so it survives rain and snow yet still opens with a firm metal feel when you bring a hand up with gloves on. The tactile resistance when you swing the door shut reinforces that this is industrial-grade kit, not a flimsy accessory.

Installation and everyday use

Honeywell sells the RXSM100A3 through generator specialists and online retailers, often bundled with its branded standby units and marketed with a five-year limited warranty. That bundle strategy matters for homeowners who want a single point of contact if something fails.

On a typical suburban install, an electrician like Maria Lopez will mount the switch beside the meter, run conduit to the main panel, and tie in the generator feeder. She can test a simulated outage in daylight, listening for the short pause and then the steady generator tone as the switch completes the handover.

Pricing and market positioning

The RXSM100A3 has been listed around 629 US dollars at specialist retailers, sitting below some premium whole-house transfer panels but above barebones manual kits. That price positions it as a practical mid-tier solution for owners who value automatic operation but do not need multi-source or three-phase complexity.

Compared with manual interlock devices or portable-generator inlet boxes, this Honeywell model adds intelligence at the service entrance. It continuously watches line conditions and moves your home onto the generator within seconds of an outage, which is a convincing step up for households that rely on sump pumps or medical equipment.

Limitations and what to watch

The main limitation is right in the name: 100 amps. Large homes with higher service ratings or heavy electric heating loads may need more capacity or a different switching scheme, which Honeywell and rivals offer in higher-amp products. Installers therefore have to match the switch carefully to the service size.

Another point is that Honeywell has marked the RXSM100A3 as discontinued at some resellers, nudging new buyers toward updated models with similar ratings. For existing installs, that mostly affects future replacement planning and makes the warranty terms more important to confirm.

Honeywell context and shares

Honeywell International Inc. builds hardware and software for aerospace, building automation and industrial process control, with backup power equipment like the RXSM100A3 fitting into its broader building technologies portfolio. The mix of long-lived gear and recurring service contracts shapes how investors look at its cash flows.

Honeywell International Inc. shares (ISIN US4448591028) trade on the New York Stock Exchange in US dollars, giving US-based retail investors straightforward access via standard brokerage accounts.

This article was AI-assisted and editorially reviewed. Product information without guarantee; prices and availability may change at short notice. No investment advice, no buy or sell recommendation. Stock-market transactions involve risks up to total loss.