Template · Multi-unit

Mixed-use building, shop and apartments single line diagram

A three-phase meter centre with a commercial unit, four apartments and a house panel. Use this for a small building with a shop or office on the ground floor and apartments above, on one three-phase service with a meter for each unit and one for the house 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

Mixed-use building, shop and apartments single line diagram: A three-phase meter centre with a commercial unit, four apartments and a house panel. — Mixed-use building, shop and apartments. 23 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 load calculation that combines the dwelling and commercial loads, the apartments’ single-phase feeders with full-size neutrals, the short-circuit rating of the meter centre, and each occupant’s access to their own disconnect.

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	120/208V 3φ 4W
Fused disconnect	Main disconnect	400A · fused 400A, service rated	Service conductors, per utility
Ground	Grounding electrode system	#2 Cu GEC
Surge protective device	SPD	Type 1
Panel	Meter centre	400A bus · 120/208V 3φ 4W	2 sets of 4 #3/0 Cu, + #3 G
Meter	Meter C1	Commercial unit
Circuit breaker	200A 3P
Panelboard	Commercial panel	200A · 120/208V 3φ	4 #3/0 Cu + #6 G
Meter	Meter A1
Circuit breaker	100A 2P
Panelboard	Apartment 1	100A · 120/208V 1φ	3 #3 Cu + #8 G
Meter	Meter A2
Circuit breaker	100A 2P
Panelboard	Apartment 2	100A · 120/208V 1φ	3 #3 Cu + #8 G
Meter	Meter A3
Circuit breaker	100A 2P
Panelboard	Apartment 3	100A · 120/208V 1φ	3 #3 Cu + #8 G
Meter	Meter A4
Circuit breaker	100A 2P
Panelboard	Apartment 4	100A · 120/208V 1φ	3 #3 Cu + #8 G
Meter	House meter
Circuit breaker	60A 3P
Panelboard	House panel	60A · stairs, fire alarm	4 #6 Cu + #10 G

Notes on the sheet

Apartments are single-phase, three-wire: two phases and the neutral of the 208Y/120V system. The neutral carries about the same current as the phases even when the load is balanced, so it is full size and counts as a current-carrying conductor.
Apartments spread across phases A-B, B-C and C-A. Ranges and dryers to be rated for 208V.
Service size from a load calculation that adds the dwelling load to the commercial and house loads: the dwelling part by NEC 220.84 where its conditions are met (electric cooking and electric heating or air conditioning in every unit), otherwise by Part III of Article 220; CEC Section 8.
Meter centre feed in two parallel sets: 2 × 200A (3/0 Cu) = 400A, on the 400A fuses. Grounding electrode conductor #2 Cu (NEC Table 250.66).
Surge protective device at the service, because it supplies dwelling units (NEC 230.67).
Each occupant has access to the disconnect for their own unit. Breakers labelled with unit numbers that match the doors.
Meter centre short-circuit rating to equal or exceed the available fault current. Whether a main disconnect goes ahead of the meters is the utility’s call: follow its metering standard.

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.