How do federal HUD and state/local codes regulate aluminum wiring in mobile/manufactured homes compared with site-built homes?
Executive summary
The federal HUD Code forbids aluminum conductors for branch-circuit wiring in manufactured (mobile) homes while allowing certain aluminum service cables and deferring to an older NEC edition for manufactured-home electrical rules [1] [2] [3]. By contrast, site-built and modular homes are regulated under state/local building codes that follow the National Electrical Code (NEC), which in its more recent provisions permits specific modern aluminum conductors when installed with approved devices [4] [1] [2].
1. HUD’s federal rule: a national ban on aluminum branch wiring in manufactured homes
HUD’s manufactured-home standard (24 CFR Part 3280 Subpart I) explicitly disallows “aluminum conductors, aluminum alloy conductors, and aluminum core conductors” for branch-circuit wiring inside manufactured homes, a regulatory choice that creates a national, federal rule applying to HUD-code homes across states [1] [2]. Manufactured homes must also follow HUD’s referenced portion of the NEC (Part II of Article 550), and HUD adopts an older NEC edition—HUD follows the 2005 NEC for these manufactured-home rules—which cements HUD’s separate, prescriptive approach to onboard electrical wiring [3].
2. Site-built and modular homes: state and local codes, NEC flexibility
Site-built homes and modular units (when they are regulated locally) are built to state and local building codes—commonly the IRC/IBC and the current NEC as adopted locally—which allow use of modern aluminum conductors under defined conditions and approved terminations [4] [5] [6]. The NEC’s more recent language (for example NEC 310.1069(B) referenced in trade reporting) recognizes newer aluminum/alloy conductor constructions and service conductors, so the same basic aluminum materials that HUD bans for branch circuits may be acceptable in site-built or modular construction when installed per manufacturer and code requirements [1] [2].
3. Why HUD differs: safety, uniform national standard, and historical context
HUD’s ban on aluminum branch conductors reflects historical concerns about older aluminum wiring installations—especially those in pre-1976 mobile homes—that were linked to connection failures and fire risk; HUD’s federal standard was created to ensure consistent safety across factory-built homes rather than leave such decisions to varied local jurisdictions [1] [7]. HUD’s single national standard purposefully diverges from local code evolution: commenters to HUD rulemaking urged alignment with state residential codes, but HUD has retained distinct limits in places based on its statutory authority and consumer-safety mandate [8].
4. Practical consequences for homeowners, buyers and tradespeople
The regulatory split means a manufactured home built to HUD standards will not use aluminum for interior branch circuits and will be held to HUD’s 2005-based electrical rules, whereas a site-built or modular home built under local adoption of the NEC may use approved modern aluminum conductors—subject to approved devices, connectors, and installation practices that address earlier failure modes [3] [2] [7]. Older mobile homes may still contain legacy aluminum wiring that predates the HUD Code and poses inspection and insurance issues, so states, lenders, and inspectors often impose upgrades or certifications [1] [7].
5. Areas of dispute and limits of the reporting
Industry and consumer groups argue both sides: some want HUD to harmonize with current NEC provisions to allow newer materials and innovations, while others stress HUD’s role in protecting consumers with a uniform national floor of safety; HUD rulemaking records show this tension and HUD’s selective adoption of code changes [8]. The available reporting documents the HUD ban and NEC allowances but does not provide the full statutory text or the most recent NEC edition language in the excerpts here, so readers should consult the actual 24 CFR 3280.801(e), HUD’s technical publications, and the current NEC adopted locally for precise installation rules and any recent changes [1] [3] [8].