Template · Commercial and industrial

347/600V service with step-down transformer single line diagram

Canadian commercial service with a 75 kVA transformer to 120/208V. Use this for a Canadian commercial service at 347/600V, with a 75 kVA step-down transformer for the 120/208V loads.

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.

Open this template in the editor Download the SVG

347/600V service with step-down transformer single line diagram: canadian commercial service with a 75 kVA transformer to 120/208V. — 347/600V service with step-down transformer. 15 devices on an 11 × 17 in sheet with a title block and notes column.

What the reviewer checks on this drawing

The reviewer checks the transformer’s primary and secondary currents and protection, the bonding of the secondary as a separately derived system, and equipment short-circuit ratings against the fault current stated by the utility.

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	347/600V 3φ 4W
Current transformer	CT cabinet	Utility metering
Fused disconnect	Main switch	400A · 600V, fused 400A
Panel	Distribution panel CDP	400A · 347/600V 3φ 4W
Circuit breaker	100A 3P	LP-1
Panelboard	Panel LP-1	347V lighting
Circuit breaker	100A 3P	T-1 primary
Transformer	Transformer T-1	75 kVA, 600V Δ – 120/208V Y	3 #3 Cu + #8 G
Circuit breaker	225A 3P	Secondary main
Panelboard	Panel PP-1	225A · 120/208V
Circuit breaker	60A 3P	RTU-1
Disconnect switch	Disconnect	60A · NEMA 3R
Load	RTU-1	Rooftop unit
Circuit breaker	30A 3P	SPD
Device	Surge protective device (SPD)

Notes on the sheet

Transformer T-1: 72A primary, 208A secondary. Secondary neutral bonded and grounded as a separately derived system.
Equipment short-circuit ratings to equal or exceed the available fault current stated by the utility.
Identify each panel and disconnect with a permanent engraved nameplate.

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.