Template · Commercial and industrial

Irrigation pump service single line diagram

A 480V three-phase service for a 75 HP pump and a centre pivot. Use this for a 480V three-phase service that exists for an irrigation pump: a meter, a small service panel, the pump starter and a circuit for a centre pivot.

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Irrigation pump service single line diagram: A 480V three-phase service for a 75 HP pump and a centre pivot. — Irrigation pump service. 14 devices on an 11 × 17 in sheet with a title block and notes column.

What the reviewer checks on this drawing

The inspector checks the pump conductors and breaker against the motor’s full-load current, the overload setting, the fused, lockable disconnect at the pivot with its grounding electrode, and the grounding electrode at the service.

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	480Y/277V 3φ 4W
Meter	Utility meter	200A socket	Service conductors, per utility
Circuit breaker	200A 3P	Main breaker	4 #3/0 Cu, service entrance
Panel	Pump service panel	200A bus · 480Y/277V 3φ
Grounding electrode	Ground rods	2 rods, 6 ft apart, #6 Cu GEC
Circuit breaker	30A 3P	SPD
Surge protective device	SPD	Type 2
Circuit breaker	150A 3P	Pump
Motor starter	Pump panel	Disconnect and size 4, starter · NEMA 3R	3 #1/0 Cu + #6 G
Motor	Irrigation pump	75 HP · 460V · 96A	3 #1/0 Cu + #6 G
Circuit breaker	20A 3P	Pivot
Fused disconnect	Pivot disconnect	30A · fused 20A, lockable · at the pivot point	3 #10 Cu + #10 G, PVC underground
Grounding electrode	Ground rod	At the pivot point
Load	Centre pivot	480V 3φ · 12A

Notes on the sheet

Pump motor 75 HP at 460V: 96A (NEC Table 430.250) × 125% = 120A. Conductors 1/0 Cu (150A at 75 °C) to match the 150A breaker, which is within the limit of NEC Table 430.52.
Pump panel has its own disconnect, within sight of the motor (NEC 430.102), and a starter with an overload relay set from the motor nameplate. Phase-loss protection is worth having on a rural three-phase line.
The centre pivot is an irrigation machine: a lockable disconnect with overcurrent protection at the point where power connects to it (NEC 675.8), and a grounding electrode at the pivot point for lightning protection (NEC 675.15). Its circuit from the machine’s nameplate.
Service load: 96A × 125% + 12A = 132A, on the 200A service, with 3/0 Cu service entrance conductors (200A at 75 °C). Some utilities want a disconnect ahead of a 480V self-contained meter: follow the utility’s standard.
Pivot conductors #10 Cu for voltage drop over the run. Burial depth per the adopted code for the wiring method used.

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.