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4 templates · Single-line diagram

Backup Generator Automatic Transfer Switch Single-Line Diagram Examples

A backup generator automatic transfer switch single line diagram shows how your standby generator, utility service, transfer switch, and critical loads connect in a simplified electrical drawing. Whether you're planning a residential whole-house backup, a commercial emergency system, or an industrial standby power installation, these examples help you visualize the power path from source to switch to load.

Standard IEEE Std 315 + ANSI device numberingEngine schematex-sldExport SVG · PNG · PDF
4 templates
Single-line diagram Backup Generator Automatic Transfer Switch
Data Center N+1 Redundant Backup Generator System Single-Line DiagramData Center N+1 Redundant Backup Generator System Single-Line DiagramBackup Generator Automatic Transfer SwitchUse template →Industrial 480V Backup Generator with Service Entrance Rated ATSIndustrial 480V Backup Generator with Service Entrance Rated ATSBackup Generator Automatic Transfer SwitchUse template →Hospital Emergency Power System: 2 MW Diesel Generator and Closed Transition ATSHospital Emergency Power System: 2 MW Diesel Generator and Closed Transition ATSBackup Generator Automatic Transfer SwitchUse template →Residential 22 kW Standby Generator with Whole-House ATS Single-Line DiagramResidential 22 kW Standby Generator with Whole-House ATS Single-Line DiagramBackup Generator Automatic Transfer SwitchUse template →

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How to

How to use a single‑line diagram template.

  1. 01Identify power sources and critical loads

    List the generator capacity, utility service voltage, ATS location, and all emergency or standby loads the system must serve.

  2. 02Add the automatic transfer switch

    Place the ATS symbol between the normal utility supply and the generator feed, then connect the load output to your emergency distribution panel.

  3. 03Draw distribution, feeders, and grounding

    Add circuit breakers, busbars, conductor types, and grounding/bonding paths to reflect the actual electrical installation.

  4. 04Label equipment ratings and settings

    Annotate each component with voltage, ampacity, interrupting rating, and ATS transition type (open or closed transition).

  5. 05Review, export, and share

    Validate the single-line diagram against your design, then export it as an image or PDF for permits, as-builts, or client review.

FAQ

Questions about single‑line diagram templates

What is a backup generator automatic transfer switch single line diagram?

It is a simplified one-line electrical drawing that shows the generator, utility service, automatic transfer switch (ATS), and connected distribution equipment using standardized symbols. It illustrates the power flow from normal and emergency sources to the load.

Do I need a service entrance rated ATS?

If the transfer switch is installed ahead of the main service disconnect, it must be service entrance rated and include a main breaker. When the ATS is downstream of a separate main breaker, a non-service rated switch can be used.

What is the difference between open transition and closed transition ATS?

Open transition breaks the connection to one source before connecting to the other, causing a brief power interruption. Closed transition overlaps both sources momentarily to avoid interruption but requires utility approval and additional protective relaying.

Can I use this diagram for a permit application?

Single-line diagrams are often required for electrical permits. They should show equipment ratings, feeder sizes, grounding, and ATS type. Your local authority having jurisdiction (AHJ) may also require a professional engineer's stamp for larger systems.

What size generator and ATS should I choose?

Select the generator based on a load calculation for all connected equipment, and size the ATS to match the generator output breaker and the service entrance rating. A licensed electrician or engineer should perform the load calculation and verify compliance with local codes.