Configuring the System
Generator Transfer Switches Explained: Whole-Home vs. Managed (and Load Shedding)
After you pick a generator size, the transfer switch is the decision that most changes your quote — because it decides what stays on during an outage. Get it right and a mid-size generator can back your whole house; get it wrong and you overpay for a unit you didn’t need.
What a transfer switch actually does
The transfer switch is the brain between your generator, your utility feed, and your electrical panel. On a home standby generator it is an automatic transfer switch (ATS): it senses the outage, disconnects your home from the grid, and starts and connects the generator — usually within seconds — then switches you back when utility power returns. That grid disconnect is not optional; it is what protects utility line workers from your generator backfeeding the lines.
(This is the difference from a portable generator, which uses a manual transfer switch or an interlock kit that you operate by hand. A permanent standby unit is automatic and unattended.)
The three real configurations
Almost every standby install is one of these three. The middle column — whole-home with load management — is the one competitors explain worst and the one that saves the most homeowners money.
| Configuration | What’s backed up | Generator size | Cost signal | Best for |
|---|---|---|---|---|
| Whole-home ATS (no load management) | The entire electrical panel — everything runs as normal. | Largest — the generator must cover your true whole-home peak. | Switch $600–$2,500 installed; drives you toward a bigger, pricier generator. | Larger homes that want zero load management and will pay for the headroom. |
| Managed / essential-circuit switch | A pre-selected set of circuits (heat, fridge, sump, well, some outlets). | Smallest — a 14–18kW unit can cover the chosen circuits. | Switch/load center $400–$1,300 installed; lowest total system cost. | Homeowners fine with running essentials, not the whole house, during an outage. |
| Whole-home ATS + load management | The whole panel is connected; modules shed big 240V loads only when needed. | Mid-size — a smaller generator backs the whole home because loads take turns. | Switch $600–$2,500 + about $169 per Smart Management Module. | The value sweet spot for most homes — whole-home coverage without the biggest generator. |
Switch cost ranges are national installed figures (see the cost guide); generator-size guidance is general. Confirm the right size for your loads with a professional load calculation — see the sizing guide.
How load management lets a smaller generator win
Here is the fact that reframes the whole decision: a 22kW generator produces only about 92 amps at 240 volts — not the 200 amps your service panel is rated for. The panel can demand more than the generator can make. Whole-home backup without load management forces you to buy a generator big enough for the worst-case moment when everything runs at once.
Load management sidesteps that. Smart Management Modules (load managers)watch your biggest 240-volt loads — AC, electric water heater, well pump, dryer, range, an EV charger — and let them take turns. When the generator nears its limit (by current or by a drop in frequency), a module sheds its load and waits before trying again, on a prioritized, time-delayed schedule. A 200-amp automatic transfer switch can manage up to eight of these modules — so a mid-size generator can back the entire panel because the heavy loads never all run at the same instant.
Why this matters for your quote
Whole-home coverage does not require the biggest generator. Whole-home coverage plus a few load-management modules often lets an 18–22kW unit do what looks like a 26kW+ job — at a lower total system cost. If a quote pushes you to a large unit for “whole-home,” ask whether load management would get you there for less.
Load-shedding behavior and the up-to-eight-modules figure: Generac and Kohler transfer-switch product documentation (Generac Smart Management Module / Load Manager; Kohler RXT load-shed kit). The ~92A output figure is 22kW ÷ 240V.
Sizing and wiring the switch correctly
- →Service-entrance (SE) rated where required. Whole-home switches come SE-rated (commonly 100A or 200A) so they can serve as the service disconnect — which several Chicago-area utilities require.
- →Don’t size the switch to the panel and stop there. A 200A switch on a 22kW generator is fine, but the generator still only makes ~92A — which is exactly why the load-management question matters more than the switch’s amp rating.
- →Neutral-to-ground bonding done right. Incorrect bonding at the transfer switch can cause GFCI trips or a shock hazard; the National Electrical Code (Article 250) governs how it’s handled. This is licensed-electrician work — another reason generator installs aren’t a DIY permit.
SE-rated amperage options: Generac/Kohler product docs. Neutral-ground bonding: NEC Article 250 (250.30 / 250.35 / 250.142). ATS output-vs-panel point: installer community consensus, filed in our evidence notes.
What the switch and modules cost
| Component | Installed cost |
|---|---|
| Automatic transfer switch (installed) | $600–$2,500 |
| Smart Management / load-shed module (each) | ~$169 |
| Subpanel (if circuits must be regrouped) | $500–$2,000 |
| Manual transfer switch (portable setups, not standby) | $400–$1,300 |
| Interlock kit (portable setups, not standby) | $400–$850 |
National installed ranges (HomeGuide, Angi, and peers), consistent with the Chicago-area labor market. The transfer switch is usually bundled into the installed price on your quote, not billed separately.
The Chicago-area utility rules
Two local points shape the switch. First, homes on Naperville’s municipal electric utility must have a transfer switch and an exterior service disconnect on every generator install — an SE-rated ATS satisfies the disconnect. Second, a standby generator with a proper transfer switch does not export to the grid, so it needs no ComEd interconnection application (that’s for solar and wind). The permits & utility guide covers both, by municipality.
Which configuration is right for you?
- 1Want everything on, budget is secondary? Whole-home ATS with a generator sized to your full peak.
- 2Want the lowest total cost and can live on essentials? A managed essential-circuit switch with a 14–18kW unit.
- 3Want whole-home coverage without the biggest generator (most people)? Whole-home ATS + load-management modules on a mid-size unit.
Whichever you choose, make sure each quote states the switch type and amperage clearly — it’s line item two on our quote comparison checklist.
Get a quote with the switch spelled out
Tell us what you want to keep running during an outage and we’ll connect you with an established local installer who’ll size the generator, the transfer switch, and any load management together — not sell you more generator than you need.
Local permit and utility rules by city: Naperville, Aurora, Wheaton, Downers Grove, Oak Brook.