Template · Service and panels

Farm service with yard pole and generator switch single line diagram

A metered yard pole with a double-throw switch for a PTO generator, feeding the house, the barn and a shed. Use this for a farm fed from a metered yard pole, with a pole-top double-throw switch for a tractor-driven generator and overhead runs to the house, the barn and a machine shed.

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Farm service with yard pole and generator switch single line diagram: A metered yard pole with a double-throw switch for a PTO generator, feeding the house, the barn and a shed. — Farm service with yard pole and generator switch. 26 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 disconnect and overcurrent protection at each building, the emergency disconnect at the house, the four-wire runs with a full-size ground, where the neutral is bonded, the grounding electrode at the pole and at each building, and the farm load calculation.

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	320A socket (CL320), on yard pole	Service conductors, per utility
Transfer switch	Double-throw switch	400A · non-fused · pole top, site-isolating device
Power inlet	Generator inlet	100A · pin and sleeve, interlocked disconnect
Generator	PTO generator	20 kW · 120/240V · 83A	Cord set
Grounding electrode	Ground rod	At pole, #6 Cu GEC
Circuit breaker	200A 2P	House main	4 250 kcmil Al, overhead
Panel	House panel	200A bus · neutrals isolated
Grounding electrode	Ground rods	At house, #6 Cu GEC
Surge protective device	SPD	Type 1 or 2
Circuit breaker	Branch breakers
To (continues off sheet)	To house circuits
Circuit breaker	200A 2P	Barn main	4 250 kcmil Al, overhead
Panel	Barn panel	200A bus · neutrals isolated
Grounding electrode	Ground rods	At barn, #6 Cu GEC
Circuit breaker	20A 1P	GFCI
Receptacle	Receptacles		2 #12 Cu + #12 G
Circuit breaker	30A 2P
Load	Ventilation fans
Circuit breaker	50A 2P
Load	Feed system
Circuit breaker	100A 2P	Shed main	4 #1 Al, overhead
Panel	Machine shed panel	100A bus · neutrals isolated
Grounding electrode	Ground rods	At shed, #6 Cu GEC
Circuit breaker	Branch breakers
To (continues off sheet)	To shed circuits

Notes on the sheet

The pole-top switch is the site-isolating device of NEC 547.9 (547.41 in the 2023 edition). It is not the service disconnect: each building has its own disconnect and overcurrent protection.
Four conductors to each building, with an equipment grounding conductor the size of the largest supply conductor (NEC 547.9(B)(3); 547.41(B)(3) in 2023). Neutral and ground are bonded at the pole-top switch, which has its own grounding electrode; at each building the neutral is isolated and a grounding electrode is connected to the equipment ground (NEC 250.32).
Each farm building’s load is taken by NEC Table 220.102, here 110A for the barn and 40A for the shed. They are combined by Table 220.103, the largest at 100% and the second at 75%: 110A + 40A × 75% = 140A. The dwelling is calculated on its own, by Part III or IV of Article 220, and added in full: 120A. Total 260A, on the 320A continuous meter socket.
PTO generator 20 kW ÷ 240V = 83A. It cannot carry the whole farm: open the loads it is not to carry before transferring.
The switch does not switch the neutral, so the generator is not a separately derived system and its neutral is left unbonded at the generator. A sign at the generator inlet says so (NEC 702.7), and a power inlet of 100A or more that is not rated as a disconnect has an interlocked disconnect (NEC 702.12).
Each main is at its building, in the panel drawn round it. The house main is outdoors and readily accessible, marked as the emergency disconnect, or has an outdoor emergency disconnect ahead of it (NEC 230.85, 2020 and later); the pole-top switch does not serve for that. Surge protective device, Type 1 or Type 2, at the house panel (NEC 230.67).
Livestock buildings: equipotential plane (NEC 547.10; 547.44 in 2023) and wiring methods for damp and corrosive locations (NEC Article 547; CEC Section 22).
This is the United States arrangement. In Ontario the runs from a central metering pole are treated as consumer’s services, bonded at each building (ESA Bulletin 10-23): confirm with the inspection authority before using it in Canada.

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.