Electrical
Service-entrance transfer switches, explained
A service-entrance rated transfer switch is listed to be the home's service disconnect, so it can be installed between the utility meter and the panel. A switch without the rating has to go after an existing disconnect. Which one you need depends on how your meter and panel are arranged, not on the generator.
What the rating means
A service-entrance rated transfer switch is listed for use as the service disconnecting means: the device that cuts all utility power to the house.
A switch without that rating is not listed for the job. It has to sit downstream of a disconnect that already exists. Neither is better in general; how your meter and panel are already arranged decides it.
One code point makes the rating more useful than it used to be. Since the 2020 edition, the National Electrical Code (section 230.85) has required one- and two-family dwellings to have an emergency disconnect in a readily accessible outdoor location. A service-entrance rated switch mounted outside, and marked as required, is one way to meet that. Which edition of the code applies depends on your city.
Why it changes the install rather than the generator
Service-entrance rating has nothing to do with the generator. The same 20kW set runs behind either one. What changes is the wiring between your meter and your panel.
- With an SE-rated switch, the switch can become the main disconnect. Service conductors land in it, and it feeds the panel. One enclosure does two jobs.
- Without one, the existing main disconnect stays where it is and the switch goes after it. If your panel has no separate upstream disconnect, one may have to be added — which is another enclosure, another set of conductors and more labor.
In that second case an SE-rated switch can make the whole job cheaper despite costing more as a part, which is why comparing switch prices on their own can mislead.
The switch is sized to your house, not your generator
A whole-house transfer switch carries the full electrical service, because when the utility is up that is what flows through it. A 200 amp service needs a 200 amp switch whether the generator behind it is 13kW or 20kW.
A switch that feeds only an essential-circuits subpanel is different: it is sized to that subpanel's feeder, and it is usually a non service-entrance switch downstream of the main.
What we stock
Across the Cummins range we carry 7 service-entrance rated configurations and 31 that are not, spanning the RA, RA CSA, OTEC families. The rating is a per-configuration attribute rather than a family-wide one, so several families offer both.
Every configuration and every price is on Cummins automatic transfer switches, 100A to 600A — this page is about which kind you need, not which one to buy.
Some generators ship with one in the box. The RS20AC includes a 200A service-entrance rated, NEMA 3R automatic transfer switch at $6,868.48, the generator and switch together.
What it changes about permits
Work at the service entrance is service work, which usually means the utility has to pull and reset the meter and the inspection has to be passed before power is restored. We schedule it, but it is a different inspection from a downstream switch. Since September 2025 a qualified third party can perform the review and inspection instead of the city, which changes the timeline — what your city can and cannot require sets out how that works.
Questions
What does service-entrance rated actually mean?
It means the switch is listed for use as the service disconnecting means, the device that cuts all utility power to the house, so it can be installed between the meter and the panel. A non service-entrance switch is not listed for that and has to sit downstream of an existing service disconnect. The difference is where the switch goes and how much rework the meter and panel need.
Do I need a service-entrance rated switch?
It depends on your existing service, not on your generator. If your panel already has a separate main disconnect ahead of it, a standard switch downstream is perfectly correct and usually cheaper. If your main breaker is inside the panel and there is no separate disconnect ahead of it, a service-entrance rated switch is often the simpler way to do it. We settle this at the survey by looking at the actual meter and panel arrangement.
Is a service-entrance switch more expensive?
The switch itself costs more. Whether the job does is a different question — an SE-rated switch can remove the need for a separate disconnect and reduce what the electrician reworks at the meter, so on some houses it lowers the total. Every configuration and price is published on the transfer switch pages, so you can compare the two paths.
Which Cummins switches are service-entrance rated?
Across the range we stock 7 service-entrance rated configurations and 31 that are not, spanning the RA, RA CSA, OTEC families. Service-entrance rating is a per-configuration attribute rather than a per-family one, so a family can offer both. Each family page states which of its configurations carry the rating.
Is the switch sized to the generator or the house?
For a whole-house switch, the house. It carries the full service, because when the utility is up everything the house uses flows through it, so a 200 amp service takes a 200 amp switch whether the generator behind it is 13kW or 20kW. A switch that feeds only an essential-circuits subpanel is sized to that subpanel's feeder instead.
We read your meter and panel before specifying anything
Which switch you need is a question about the house, and we answer it at the free survey.
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Related across UTS
- A service-entrance switch often goes in alongside panel or meter work.Electrical panel and service upgrades from Clements Electric.