Template · EV chargers

Bidirectional charger with home backup single line diagram

A vehicle-to-home charger behind a service-rated backup gateway that islands the house in an outage. Use this for a bidirectional charger that lets the vehicle run the house in an outage. A service-rated gateway ahead of the main panel separates the house from the grid before the vehicle supplies it.

A free template with typical ratings, conductor callouts and general notes. Open it, change what differs on your job, fill in the title block and export a PDF.

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Bidirectional charger with home backup single line diagram: A vehicle-to-home charger behind a service-rated backup gateway that islands the house in an outage. — Bidirectional charger with home backup. 10 devices on an 11 × 17 in sheet with a title block and notes column.

What the reviewer checks on this drawing

The reviewer looks for a charger listed for bidirectional use, the gateway as the service disconnect with the panel neutrals isolated behind it, the busbar arithmetic, how the house load is kept within what the vehicle can supply, and the utility’s approval where the vehicle can run in parallel with the grid.

What the drawing shows

Every device on the sheet, in the order power reaches it.

Symbol	Label	Rating or detail	Conductors feeding it
Utility source	Utility service	120/240V 1φ 3W
Meter	Utility meter	200A socket	Service conductors, per utility
Device	Backup gateway (MID)	Microgrid interconnect device, 200A · service rated, main breaker inside
Ground	Grounding electrode system	GEC moved to the gateway
Panel	Main panel	225A bus · neutrals isolated	3 #3/0 Cu + #6 G
Circuit breaker	Branch breakers
To (continues off sheet)	To all house loads
Surge protective device	SPD	Type 1 or 2
Circuit breaker	60A 2P	Bidirectional EVSE
EV charger	Bidirectional EVSE	48A · 11.5 kW charging, 40A · 9.6 kW to the house	2 #6 Cu THHN + #10 G, 3/4" EMT

Notes on the sheet

EVSE listed for bidirectional use (NEC 625.48). Supplying the house in an outage makes it an optional standby system (NEC Article 702); running in parallel with the utility also brings in Article 705 and the utility’s approval.
Gateway opens on loss of utility before the vehicle supplies the house. It is the service disconnect: grounding electrode conductor and main bonding jumper at the gateway, main panel neutrals isolated.
Charging is a continuous load: 48A × 125% = 60A. To the house: 9.6 kW ÷ 240V = 40A. A neutral to the EVSE where its manufacturer requires one.
The whole panel is on a 9.6 kW source: a load calculation shows the house within it, or the gateway’s load control holds the large loads off (NEC 702.4).
Busbar check: 225A bus × 120% = 270A ≥ 200A + 60A, EVSE breaker at the far end of the bus from the supply. On a 200A bus, fit a smaller main in the gateway or a power control system (NEC 705.13).
Surge protective device at the panel (NEC 230.67). Gateway outdoors and marked EMERGENCY DISCONNECT, SERVICE DISCONNECT, or an outdoor emergency disconnect ahead of it (NEC 230.85). A sign at that emergency disconnect gives the type and location of the standby source (NEC 702.7).
Vehicle, EVSE and gateway to be a combination their manufacturers list for use together.

Diagram is schematic and not to scale. Field-verify existing equipment ratings. Ratings and conductor sizes shown are typical. Confirm against the adopted code, the equipment listing and a load calculation before installation. Code references are to the 2023 NEC and the 2024 Canadian Electrical Code: see references and editions.