Technical Bulletin 2 - Aluminum & Galvanized Steel Rigid Conduit & EMT Usage

Sep 23, 2026

Technical Bulletin 2 (2/2022) explains the shift in electrical construction from galvanized steel rigid conduit to aluminum rigid conduit and aluminum EMT. It outlines key benefits of aluminum, including lower component cost, improved jobsite efficiency, safety, corrosion resistance, non-sparking performance, and sustainability. The bulletin clarifies allowable usage locations, then summarizes relevant UL/ANSI/NEC points and the differences between UL6/UL6A and UL797/UL797A, focusing on construction, coatings, and material limitations.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages8

Reading Time20 min

AccessFree to download

Aluminum vs. Galvanized Steel Conduit and EMT

Benefits of Aluminum Products

Acceptable Usage Locations and Exceptions

Penn Aluminum Approval and Use Cases

Underwriters Laboratories (UL) and ANSI Framework

Rigid Metal Conduit (RMC) and UL6/UL6A

Section 3 Definitions

Section 5 Construction Requirements

Coatings, Corrosion Resistance, and Applications

Electrical Metallic Tubing (EMT) and UL797/UL797A

UL EMT Standards and Material Differences

Dimensions, Weight, and Alloy Content

Construction and Coating Requirements

TECHNICAL BULLETIN 2 2/2022 Aluminum & Galvanized Steel Rigid Conduit & EMT Usage A current trend in the Electrical Construction Industry is the transition from using galvanized steel to Aluminum rigid conduit and electrical metallic tubing (EMT) . This transition is being driven by the numerous benefits Aluminum conduit products provide compared to equivalent galvanized steel products. These benefits include: • Lower Cost of Components • Improved Efficiency on the Jobsite (Lower Total Installed Cost) • Safety (Aluminum weighs 1/3 that of steel and dissipates heat) • Corrosion Resistant Alloy • Non-sparking metal (eliminating a hazard in explosive atmospheres) • Sustainability (100% recyclable & made from recycled Aluminum) As more projects and electricians recognize the opportunity for increased profitability and enhanced safety presented by using Aluminum Rigid Conduit and Aluminum EMT, Penn Aluminum receives inquiries related to the acceptable usage of our Aluminum products in the field. The answer to these inquires is that Aluminum may be used in nearly all electrical construction locations where galvanized steel conduit products have historically been used , with few exceptions. These exceptions are clearly identified in UL, ANSI and National Electrical Code (NEC/NFPA) standards, articles and specifications. Penn Aluminum Rigid Conduit can be used indoors or outdoors. It is approved for dry or wet locations where determined suitable for the environment. Penn Aluminum EMT is used most commonly in dry interior spaces, but it is permitted to be used in damp locations with corrosion-resistant hardware and rain-tight fittings. Underwriters Laboratories (UL) also American National Standards Institute (ANSI) RIGID METAL CONDUIT (RMC) UL authorizes the listing and use of the UL mark for Electrical Rigid Metal Conduit in two Standards for Safety. UL6 Standard for Safety-Electrical Rigid Metal Conduit – Steel UL6A Standard for Safety-Electrical Rigid Metal Conduit – Aluminum and Stainless Steel In Section 3, Definitions, of each of these Standards, Electrical Rigid Metal Conduit is defined the same except for referencing the difference in material. “Electrical Rigid Metal Conduit – steel (ERMC-S) or aluminum (ERMC-A)–A threadable steel (or aluminum) raceway of circular cross-section designed for the physical protection and routing of wire conductors and use as an equipment grounding conductor when installed utilizing appropriate fittings. All measurable dimensions relating to the conduit tube or pipe, couplings, elbows and nipples are identical between these two UL standards. Due to the difference in weight (Aluminum being 1/3 the weight of steel), the standards reflect this variance in the same Table 5.2 Length and Weight of Finished Conduit, but the lengths by trade sizes shown are the same. Section 5 – Construction Section 5 of both the UL6 and UL6A standards present the requirements for all of the conduit products covered. Due to the fact that the steel tube used for rigid conduit is a product that is welded and susceptible to corrosion, a good portion of this section in the UL6 standard details the weld bead limitations and protective coating (normally zinc galvanization) requirements (5 .3) . Penn Aluminum Rigid Conduit is manufactured using aluminum extrusion technology that does not create the weld bead that is of concern in the UL6 standard for rolled-and-welded steel tube. The UL6A Standard references a maximum copper content percentage of no more than 0.40% in the alloy of the Aluminum used in the construction of the tube. This content percentage is not a concern due to the design specified 6061 series recycled Aluminum alloy Penn Aluminum uses for production of our RMC products. Aluminum is a corrosion resistant material. Section 5.3 of the UL6A standard directly states that Electrical rigid metal conduit made of aluminum does not require a protective coating. Th

FAQs

Why is the industry transitioning from galvanized steel to aluminum rigid conduit and EMT?

The bulletin states aluminum conduit offers lower component cost, improved jobsite efficiency with lower total installed cost, enhanced safety, corrosion-resistant alloy performance, non-sparking behavior, and sustainability through recyclability and recycled content.

In what electrical construction locations can aluminum conduit be used?

Aluminum may be used in nearly all locations where galvanized steel conduit has historically been used, with exceptions clearly identified in UL, ANSI, and NEC/NFPA standards, articles, and specifications.

What coating requirements differ between UL6 (steel) and UL6A (aluminum) rigid metal conduit?

UL6 details weld bead limitations and protective coating requirements for steel, while UL6A states aluminum rigid metal conduit does not require protective coating; however, protective coatings may be used, and coatings are required for specific cases such as concrete use, direct burial, or severely corrosive environments.

Sep 23, 2026

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