200A 120/208V commercial service single line diagram
A small three-phase service for a shop or office: meter, main breaker and one panel. Use this for a small shop, office or restaurant unit with its own 200A 120/208V three-phase service: a meter, a main breaker and one panel.
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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What the reviewer checks on this drawing
The reviewer checks the service entrance conductors and grounding electrode conductor, the available fault current against the equipment ratings, the load calculation, and the rooftop unit’s breaker and conductors against its nameplate.
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 | |
| Meter | Utility meter | 200A socket | Service conductors, per utility |
| Circuit breaker | 200A 3P | Main breaker | 4 #3/0 Cu, service entrance |
| Panel | Panel MDP | 200A bus · 120/208V 3φ 4W | |
| Ground | Grounding electrode system | #4 Cu GEC | |
| Circuit breaker | 30A 3P | SPD | |
| Surge protective device | SPD | Type 2 | |
| Circuit breaker | 50A 3P | RTU-1 | |
| Disconnect switch | Disconnect | 60A · NEMA 3R | 3 #8 Cu + #10 G |
| Load | RTU-1 | MCA 38A · MOCP 50A | |
| Circuit breaker | 30A 2P | ||
| Heater | Water heater | 4.5 kW · 208V | 2 #10 Cu + #10 G |
| Circuit breaker | 20A 1P | ||
| Lighting | Lighting | ||
| Circuit breaker | 20A 1P | ||
| Receptacle | Receptacles | 2 #12 Cu + #12 G | |
| Circuit breaker | 20A 1P | ||
| Load | Sign circuit | ||
| Circuit breaker | Spare |
Notes on the sheet
- Service entrance 3/0 Cu (200A at 75 °C) on the 200A main. Grounding electrode conductor #4 Cu for 3/0 Cu service conductors (NEC Table 250.66).
- Available fault current from the utility marked on the service equipment with the date (NEC 110.24). Equipment short-circuit ratings to equal or exceed it.
- RTU-1 breaker does not exceed the nameplate MOCP; conductors sized from the MCA. Replace both with the nameplate data of the installed unit.
- Water heater 4.5 kW ÷ 208V = 21.6A; × 125% = 27A, protected at 30A.
- A 20A sign circuit to each tenant entrance, with nothing else on it (NEC 600.5).
- Load calculation and a typed panel directory submitted with this drawing.
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.
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