Specialized Electrical Systems
Process power, emergency generation, and equipment-only electrical capacity are classified by function under Treas. Reg. §1.48-1, court tests, and IRS examiner matrices. Building life-safety power usually stays with the building. Mixed primary systems have been allocated by design load in some cases and rejected in others. This page is educational information, not tax advice.
Educational information, not tax advice.
Updated 2026-10-14
Key takeaways
- Treas. Reg. §1.48-1(e)(2) lists electric wiring among structural components relating to operation or maintenance of a building.
- Scott Paper allocated a mill’s primary electrical system by machinery design load; A.C. Monk rejected percentage allocation on tobacco-plant facts.
- Publication 5653 discusses functional allocation for primary and secondary electrical distribution; that method is not an IRS-accepted allocation for plumbing or HVAC.
- Whiteco’s six permanence factors are a court test, not a statute, and they do not replace the structural-component list.
- One-line diagrams, demand-load calculations, and photographs of dedicated panels are the usual supporting file.
A specialized electrical system exists to run a process: a kitchen line, an imaging suite, a manufacturing motor, or information-technology load. Treas. Reg. §1.48-1 still starts the analysis. Tangible personal property is any tangible property except land and improvements such as buildings or other inherently permanent structures, including structural components of those buildings. A building is a structure enclosing space, usually covered by a roof, whose purpose is shelter, housing, or working, office, parking, display, or sales space. Structural components include electric wiring and lighting fixtures and other components relating to the operation or maintenance of a building. Local fixture law does not control.
Hospital Corp. of America & Subs. v. Commissioner, 109 T.C. 21 (1997), held that those investment-credit definitions still decide whether an item is section 1245 personal property or a section 1250 structural component under MACRS. The IRS Action on Decision 1999-008 acquiesced in that legal test and not in the court’s item-by-item results. A later study cannot treat an HCA hospital schedule as a catalog of five-year property for a different building.
Scott Paper Co. v. Commissioner, 74 T.C. 137 (1980), is the leading mixed-system example. The Tax Court treated a pulp mill’s primary electrical improvements as a structural component only to the extent they powered overall building operation and maintenance, and as tangible personal property to the extent they served production machinery. The split followed machinery design load. Morrison, Inc. v. Commissioner, 891 F.2d 857 (11th Cir. 1990), affirmed a similar load-based split for cafeteria buildings. A.C. Monk & Co. v. United States, 686 F.2d 1058 (4th Cir. 1982), rejected percentage allocation and asked whether electrical components could reasonably be adapted to more general uses. Courts have split on the same kind of asset depending on facts and forum.
Whiteco Industries, Inc. v. Commissioner, 65 T.C. 664 (1975), supplies six questions for whether property other than machinery is inherently permanent: whether it can be and has been moved; whether it is designed to remain permanently in place; expected length of affixation; how hard removal is; damage on removal; and manner of affixation. Those questions are a court test, not a statute. They matter when someone argues that a generator skid or a switchgear house is an inherently permanent structure. They do not erase the regulation’s list of wiring as a structural component when the wiring relates to operating the building.
IRS Publication 5653 (Rev. 2-2025), the Cost Segregation Audit Techniques Guide, is examiner guidance and states that it is not an official pronouncement of law. Chapter 8.A discusses functional allocation of primary and secondary electrical distribution by design or demand load to section 1245 end uses, and it tells examiners that a properly applied allocation of that kind should not be challenged. The guide does not present that method as an IRS-accepted allocation of plumbing or HVAC. Industry matrices add fact-pattern rows: the casino and gaming matrix treats emergency generators for building life-safety as building property and generators for casino operations as recreation-activity property. Those rows describe general patterns for that industry, not a national generator class.
What the regulation actually lists
Section 1.48-1(e)(2) names electric wiring among structural components. The list also includes lighting fixtures, plumbing, central air conditioning or heating, partitions, floors, ceilings, sprinkler systems, and fire escapes. The catch-all is other components relating to the operation or maintenance of a building. Specialized electrical work is still wiring. The classification question is whether a particular run, panel, or generator relates to occupying the building or to a process that would leave if the equipment left.
The regulation’s sole-justification exception is written for machinery required to meet temperature or humidity needs essential to other machinery or to processing materials or foodstuffs. It is not an electrical-allocation rule. Process power arguments rest on Scott Paper, Morrison, Hospital Corporation of America, and the audit guide’s electrical chapter, not on that HVAC sentence.
How Publication 5653 discusses specialized power
The industry matrices in Chapter 7 separate building electrical from equipment electrical by function. Restaurant dedicated outlets travel with kitchen equipment. Residential dedicated 220-volt range and dryer circuits are treated as following the appliances, while general kitchen wiring stays with the building. Pharmaceutical process power is personal property with an activity-class life. Guest-room general-use outlets, including bath GFI, are building in the casino and hotel matrix. Examiners are told those matrices reflect general fact patterns for one industry and may not apply to others.
Chapter 8.A is the electrical-distribution discussion. It is limited to primary and secondary electrical distribution. Branch circuits that exist only to serve a named machine are a different, usually simpler, documentation problem: show the homerun. Do not paste a mill-wide load percentage onto a grocery store service or onto a rooftop HVAC unit.
Courts split on mixed electrical systems
Scott Paper and Morrison used design load to split a primary system that served both buildings and machinery. A.C. Monk used adaptability to more general uses and denied credit after remand. Hospital Corporation of America applied Scott Paper analysis under MACRS and classified hospital items one by one. None of those opinions publishes a percentage that a later taxpayer can drop into a panel schedule. Boddie-Noell Enterprises, Inc. v. United States, 36 Fed. Cl. 722 (1996), rejected after-the-fact percentage estimates of HVAC, electrical, and plumbing shares that were not tied to contemporaneous records.
AmeriSouth XXXII, Ltd. v. Commissioner, T.C. Memo. 2012-67, is the modern residential caution. Most claimed special electric items in garden apartments stayed with the 27.5-year buildings. Appliance outlets and some data outlets were among the few items the taxpayer kept. A specialized-electrical claim in apartments is not the same case as a paper mill expansion.
Whiteco is a permanence test, not a wiring statute
Whiteco involved outdoor advertising signs on poles set in concrete. The Tax Court held they were not inherently permanent and qualified as tangible personal property. The IRS later applied those six questions in Rev. Rul. 2003-54 to stand-alone gasoline pump canopies and their footings. Canopies were classified as personal property in class 57.0; the poured footings as petroleum-marketing land improvements in class 57.1. That ruling is about canopies, not switchgear. Use Whiteco when the dispute is whether a structure is inherently permanent. Use the structural-component list and the functional cases when the dispute is building wiring versus process wiring.
Documentation that examiners can test
Publication 5653 Chapter 4 lists what a quality study uses: original cost records or a documented estimate, a site visit with photographs, drawings and specifications, a legal analysis, and a reconciliation to total cost. For specialized electrical systems that usually means one-line diagrams, panel schedules, demand-load calculations showing what the specialized capacity is designed to serve, and photographs of dedicated panels, generators, or equipment feeds. Naming every feeder “process power” in a report does not substitute for those records.
Cost estimation methods the audit guide describes — detailed engineering from actual costs, detailed engineering estimates from published unit costs, residual estimation, and sampling — are examiner-observed approaches. CostSeg SI has described a proposed Super Intelligence workflow for extraction and classification; that product description is proposed, not an operational claim that drawings are extracted or that any published cost book is applied automatically. This page is educational information, not tax advice.
Sources
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- 10IRS 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.
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