General Electrical Distribution
Service, house panels, and convenience circuits that light and power the building are listed structural components under Treas. Reg. §1.48-1(e)(2). A mixed primary system has been split by design load in some cases. Publication 5653 limits that functional allocation to primary and secondary electrical distribution. This page is educational information, not tax advice.
Educational information, not tax advice.
Updated 2026-10-14
Key takeaways
- Electric wiring relating to operation or maintenance of a building is a listed structural component.
- Treas. Reg. §1.263(a)-3 treats the electrical system as a building system for repair-versus-improvement testing; that unit-of-property rule is not itself a depreciation class.
- Scott Paper and Morrison allocated mixed primary systems by load; A.C. Monk rejected allocation on different facts.
- The IRS audit guide accepts functional allocation only for primary and secondary electrical distribution, not as a plumbing or HVAC method.
- Do not treat an entire service as short-life property because some downstream load is equipment.
General electrical distribution is the path from the utility to the building’s lights, receptacles, and building equipment. Treas. Reg. §1.48-1(c) defines tangible personal property as any tangible property except land and improvements such as buildings or inherently permanent structures, including structural components. Section 1.48-1(e)(1) defines a building as a structure enclosing space, usually roofed, used for shelter, housing, or working, office, parking, display, or sales space. Section 1.48-1(e)(2) then lists electric wiring among structural components, together with lighting fixtures and other components relating to the operation or maintenance of a building.
That listing is why a house panel, a corridor lighting homerun, and a general-use receptacle circuit ordinarily travel with the building’s recovery period — 27.5 years for residential rental property that meets the dwelling-unit test, or 39 years for nonresidential real property. Hospital Corp. of America held that these former investment-credit tests still apply under MACRS. The IRS acquiesced in the legal test, not in every hospital item the court classified.
Scott Paper allocated mixed-use primary electrical cost using machinery design load. Morrison affirmed a cafeteria allocation on the same theory and focused on the ultimate use of electricity. A.C. Monk, binding in the Fourth Circuit, rejected percentage allocation and asked whether the components could reasonably be adapted to more general uses. The same asset category — a primary distribution system — produced different outcomes because the facts and the forum differed. Publication 5653 Chapter 8.A tells examiners not to challenge a properly applied functional allocation of primary and secondary electrical distribution. The guide does not extend that method to plumbing or HVAC as an IRS-accepted allocation.
Whiteco’s six permanence factors remain the court test for whether property other than machinery is an inherently permanent structure. They are not a statute, and they are a poor substitute for the wiring list when the item is plainly part of the building’s electrical system. Rev. Rul. 2003-54 used Whiteco to classify gasoline pump canopies, not building services. Rev. Rul. 2003-81 reminds readers that an asset described in both an asset category (classes 00.11 through 00.4) and an activity category is generally placed in the asset category unless the activity class specifically includes it.
Industry matrices in Publication 5653 illustrate the building side of the split. Guest-room general-use outlets are building in the casino and hotel matrix. General kitchen wiring is building in the residential rental matrix. Building electrical rows in retail, restaurant, and auto-dealership matrices are section 1250. Those matrices are examiner guidance for stated industries. They are not a rule that every conductor in every building is 39-year property, and they are not a license to reclass a whole service because a kitchen has a few dedicated circuits.
Building system versus recovery class
Treas. Reg. §1.263(a)-3(e)(2)(ii) lists electrical systems — wiring, outlets, junction boxes, lighting fixtures and connectors, and site utility equipment from the property line — as a building system for deciding whether an expenditure is an improvement. That regulation is a repair and capitalization rule. It is consistent with treating general distribution as a structural component, but it does not assign a MACRS class by itself.
A lighting-system replacement can therefore be a capital improvement to the electrical building system and still be recovered with the building unless a narrower class is supported on the facts. Classification and capitalization are sequential questions.
What functional allocation does and does not do
When a primary or secondary system serves both building occupancy and process equipment, Scott Paper used design load as the split. Publication 5653 Chapter 8.A is the IRS examiner discussion of that approach. It applies to primary and secondary electrical distribution. Dedicated branch circuits that exist only for a named machine are documented as dedicated equipment wiring, not as a percentage of the incoming service.
Do not extend the electrical allocation method to a mixed plumbing riser or a mixed rooftop HVAC unit and describe that extension as IRS-accepted. Restaurant matrices in the audit guide say allocation of HVAC is not appropriate. Plumbing fixtures are listed structural components. Those are different tests.
AmeriSouth and Boddie-Noell as evidence warnings
AmeriSouth kept most special-electric claims with apartment buildings and allowed a narrow set of appliance and data outlets. Boddie-Noell found percentage estimates of electrical, plumbing, and HVAC shares too unreliable when they rested on after-the-fact studies of a few restaurants extrapolated to the rest. Both opinions punish thin files more than they announce a national class life for building wire.
Activity class after the section 1245 determination
If a portion of distribution is supported as section 1245 property, recovery period still depends on Rev. Proc. 87-56 classes as reproduced in IRS Publication 946, Appendix B. Distributive trades and services personal property often falls in class 57.0. Recreation assets may fall in class 79.0. Manufacturing activity classes differ. Rev. Rul. 2003-81: check asset categories first, then activity categories. The class-life step comes after the personal-property versus structural-component step.
Plans, photographs, and load support
Drawings, panel schedules, and a load study that identifies building versus process end uses are the documents that make a mixed-system allocation testable. Photographs of house panels and of labeled process panels help an examiner see the same split the report describes. Publication 5653 Chapter 3 lists detailed engineering from actual cost records as generally the most accurate costing approach examiners see, and residual estimation as simpler and potentially less accurate. Those are study methods described in the guide, not live CostSeg SI product features. This page is educational information, not tax advice.
Sources
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- 9IRS Publication 5653 — Cost Segregation Audit Techniques Guide (rev. 2-2025)(opens in a new tab)
Written for IRS examiners. The guide states it is not an official pronouncement of law and cannot be cited as authority. It predates the July 2025 law.
- 10IRS Publication 946 — How To Depreciate Property (2025)(opens in a new tab)
Appendix B reproduces the Rev. Proc. 87-56 class lives.
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