Engineers cite data, not adjectives. When a specification sheet needs the density of 316 stainless, the thermal conductivity of 5052 aluminum, or the yield strength of 6061-T6 at a mounting plate, the number should come from a consistent, traceable table — not from whichever supplier page loaded fastest. This reference collects the physical and mechanical constants that electrical enclosure work actually uses: the two stainless grades, the two aluminum alloys, the carbon-steel workhorses, and the copper alloy that carries current inside the cabinet. Use it for weight estimates, thermal spreadsheets, material trade-off memos, and enclosure specification clauses; final specifications must be verified against the governing standard edition and the mill certificate.
Material properties master table
Values are room-temperature (20 °C) handbook values consistent with ASM Metals Handbook data, ASTM product standards (A240 for stainless plate and sheet, B209 for aluminum sheet and plate, B221 for extrusions), and Copper Development Association publications for C11000.
| Material | Density (g/cm³) | Thermal conductivity (W/m·K) | Electrical resistivity (µΩ·cm, 20 °C) | Conductivity (%IACS) | Yield strength, typical (MPa) | CTE (µm/m·K) |
|---|---|---|---|---|---|---|
| 304 stainless, annealed | 8.00 | 16.2 | 72 | 2.4 | 215 (min 205, ASTM A240) | 17.2 |
| 316 stainless, annealed | 8.00 | 16.3 | 74 | 2.3 | 240 (min 205, ASTM A240) | 16.0 |
| 5052 aluminum, H32 | 2.68 | 138 | 4.9 | 35 | 193 (min 130, ASTM B209) | 23.8 |
| 6061 aluminum, T6 | 2.70 | 167 | 4.0 | 43 | 276 (min 240, ASTM B221) | 23.6 |
| Cold-rolled low-carbon steel (CRCA) | 7.87 | ≈50 | ≈16 | ≈11 | 170–250 (temper-dependent) | 11.7 |
| Galvanized steel (G90 coating) | 7.87 | ≈50 | ≈16 | ≈11 | follows base steel | ≈12 |
| Copper busbar, C11000 / E-Cu | 8.89 | 391 | 1.72 | 100 | ≈70 annealed / ≈310 hard-drawn | 17.0 |
Notes: %IACS conductivity is referenced to annealed copper (1.72 µΩ·cm = 100%). The 304/316 minimums are the ASTM A240 annealed minimums; commercial sheet typically tests above them. Copper yield strength depends almost entirely on temper — busbar is usually supplied in a hard or half-hard temper for stiffness, while conductivity is essentially temper-invariant.
304 and 316 stainless steel: the corrosion benchmarks
304 is the default corrosion-resistant enclosure material for food processing, general washdown-adjacent duty, and outdoor service away from chlorides. 316 adds molybdenum (2–3%), which is what buys resistance to chlorides — marine coastlines, brine, and aggressive chemical washdown. This is why coastal NEMA 4X projects default to 316 while inland 4X duty is routinely served by 304. Both austenitic grades work-harden rather than hardening by heat treatment, form well, and weld by common processes. For selection context, see the stainless steel enclosure range and the NEMA to IP converter for the rating side of the decision.
5052 and 6061 aluminum: sheet and structure
5052-H32 is the sheet alloy of aluminum enclosure building: excellent bend formability, very good corrosion resistance in marine atmospheres (it contains magnesium, no copper), and a density that makes a like-for-like door roughly 2.9× lighter than steel. 6061-T6 is the structural alloy — mounting plates, chassis frames, and extruded profiles — noticeably stronger in yield (276 vs 193 MPa typical) but markedly less friendly to tight bends, which is why fabricators route 5052 to covers and doors and 6061 to machined plates. Both alloys carry roughly 35–43% IACS conductivity; their thermal conductivity (138–167 W/m·K) is roughly ten times stainless, which matters when an enclosure wall is asked to double as a heat sink — model that duty with the enclosure temperature rise calculator. Application context: aluminum enclosures.
Cold-rolled and galvanized steel: the cost workhorses
Cold-rolled low-carbon steel (CRCA/SPCC class) is the volume material of painted control cabinets: best stiffness per dollar, straightforward punching and folding, and a paint system that carries indoor duty for decades. Its weakness is corrosion the moment the coating is breached — at cut edges, fasteners, and gasket lines. Hot-dip galvanized steel (G90 class) buys zinc sacrificial protection for outdoor, agricultural, and cost-sensitive external duty; the coating protects cut edges cathodically, though the protection radius is finite. Neither is suitable bare in washdown or chloride service. For the painted-steel route, see carbon steel enclosures; the full material-by-application breakdown lives under enclosure materials.
Copper busbar (C11000): the conductor inside the cabinet
C11000 (99.9% Cu, E-Cu per EN) is the standard busbar alloy — 100% IACS, 391 W/m·K thermal conductivity, and yield strength that scales with temper from ~70 MPa annealed to ~310 MPa hard-drawn. Enclosure builders size busbar cross-sections against ampacity, enclosure temperature-rise limits, and short-circuit bracing forces rather than against yield alone. Common flat-bar sections run from 3×15 mm for small distribution blocks to 10×100 mm and beyond for main incomers; for the conductor-sizing side of the calculation, the wire size calculator (NEC 310.16 chart) covers the ampacity table logic, and the transformer kVA calculator converts upstream ratings into the currents the busbar must carry.
Typical sheet thickness in enclosure fabrication
| Material | Typical enclosure thickness (mm) | Where used |
|---|---|---|
| 304 / 316 stainless | 1.2 / 1.5 / 2.0 | Doors, bodies, hygienic enclosures |
| 5052-H32 aluminum | 1.5 / 2.0 / 2.5 / 3.0 | Bent covers, lightweight bodies |
| 6061-T6 aluminum | 3–6 plate; extruded profile | Mounting plates, frames, chassis |
| Cold-rolled steel | 1.0 / 1.2 / 1.5 / 2.0 | Control cabinet bodies, doors, mounting plates |
| Galvanized steel (G90) | 1.0 / 1.2 / 1.5 / 2.0 | Outdoor utility and agricultural cabinets |
| Copper C11000 | 3–10 thick × 15–100 wide | Busbar, neutral bars, PE bars |
Which material for which enclosure duty
| Duty / environment | Default material | Why |
|---|---|---|
| Food, beverage, pharma washdown | 316 | Chloride and cleaning-chemical resistance |
| Coastal / marine NEMA 4X | 316 (or 5052 where weight matters) | Salt-spray performance |
| General indoor control panel | Painted cold-rolled steel | Stiffness per dollar |
| Outdoor, cost-sensitive | Galvanized G90 | Sacrificial edge protection |
| Weight-critical / marine-adjacent | 5052-H32 | 2.9× lighter than steel at equal thickness |
| Mounting plates, structural frames | 6061-T6 | Yield strength, machinability |
Worked example: enclosure weight from density
Density converts a drawing into a shipping weight in one step. A 500 × 400 mm door in 1.5 mm 304 stainless has a volume of 0.5 × 0.4 × 0.0015 = 3.0 × 10⁻⁴ m³; at 8.00 g/cm³ (8,000 kg/m³) the flat-sheet weight is 2.4 kg before flanges and stiffeners. The same door in 2.0 mm galvanized steel: 0.5 × 0.4 × 0.002 × 7,870 ≈ 3.1 kg; in 2.0 mm 5052 it is ≈1.1 kg. These weight ratios — stainless ≈3× aluminum, steel ≈2.9× aluminum at equal thickness — are the recurring arithmetic behind material substitution decisions, which is why the density column of the master table earns its citations.
How to cite these values
In a specification or report, cite the governing document, not this page: room-temperature physical constants to ASM Metals Handbook or an equivalent recognized handbook; minimum mechanical properties to the product standard (ASTM A240 for annealed stainless sheet and plate, ASTM B209 for aluminum sheet, ASTM B221 for extrusions, EN 1652 for copper strip busbar stock); conductivity units to the IACS convention (annealed copper = 100%). This page exists to make the comparison and the first-pass sizing fast — the standard edition and the mill certificate remain the documents of record.
Frequently asked questions
What is the density of 304 stainless steel?
8.00 g/cm³ (8,000 kg/m³). Type 316 is the same nominal 8.00 g/cm³ — the molybdenum addition shifts density negligibly for weight estimating.
How much lighter is an aluminum enclosure than steel?
At equal thickness, roughly 2.9× — the density ratio between low-carbon steel (7.87) and 5052 aluminum (2.68). Aluminum enclosures often close part of that gap with thicker sheet for stiffness, so realized weight savings of 40–55% are typical in practice.
Which stainless grade for washdown duty?
316 wherever chlorides or hypochlorite cleaning are present; 304 is serviceable in general food-area duty but pitting in chloride service is the classic field failure that 316 exists to prevent.
Does enclosure material affect heat dissipation?
Yes — wall conductivity sets how much internal heat the enclosure shell can shunt to ambient. Aluminum (138–167 W/m·K) is roughly 8–10× more conductive than stainless (≈16), which is why identical internal loads run cooler in aluminum or steel walls than in stainless. Quantify it with the enclosure temperature rise calculator before specifying cooling.
Why does copper busbar temper matter so little for ampacity?
Temper changes yield strength (≈70 → ≈310 MPa) but leaves electrical conductivity essentially untouched — C11000 sits at 100% IACS annealed or hard-drawn. Ampacity is set by cross-section, enclosure temperature-rise limits, and short-circuit bracing, not hardness.
ElectricalCabinet.net fabricates stainless steel, aluminum, and steel enclosures to these same material standards, build-to-spec from single units upward.
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