Overview
ASTM B187/B187M-26 covers copper conductor bar, rod and shapes for electrical bus applications plus rod, bar and shapes for general purposes. The order must distinguish electrical from general duty and define UNS, temper, section, length, straightness, edge radius, conductivity, mechanical tests and B249 general requirements.
Designation and acceptance
B187/B187M is both an electrical conductor-product and general-purpose copper long-product specification. Bus-bar acceptance can require electrical resistivity/conductivity and carefully controlled section geometry, while general-purpose rod and shapes may prioritize mechanical and fabrication requirements. The standard does not specify a fabricated busway, plating, insulation, joints or installed temperature-rise performance.
Members and selection
| Designation | Selection context |
|---|---|
| Conductor bus bar | Specify copper UNS, temper, rectangular section, edge radius, straightness and conductivity for the electrical design. |
| Electrical rod and shapes | Define cross-section and electrical acceptance rather than treating every copper extrusion as bus-grade. |
| General-purpose rod | Use with the required temper, diameter, length, straightness and downstream machining/forming plan. |
| General-purpose bar and shapes | Provide section drawing, tolerances, corner/edge requirements and inspection method. |
Comparison framework
| Criterion | Decision context |
|---|---|
| Electrical vs general duty | Bus products prioritize conductivity and geometry; general products can use different property and fabrication priorities. |
| Temper | O60 soft and H04 hard traditions illustrate how condition changes formability, strength and straightness. |
| Section geometry | Thickness, width, diameter, straightness, edge contour and corner radius are functional order data. |
| Material vs assembly | B187 qualifies copper stock, not holes, plating, insulation, bolted joints or assembled switchgear performance. |
Performance
- Acceptance under ASTM B187 Copper Bars depends on the exact alloy or grade, delivered condition, product geometry and specified test basis rather than the standard number alone.
- Local section loss, poor flatness, burrs or contaminated contact surfaces can cause heating despite acceptable bulk conductivity.
- Service suitability remains an engineering decision: stock conformance does not establish joint resistance, short-circuit capacity, insulation rating or finished assembly compliance.
Orderable product scope
- Rectangular copper bus bar in straight lengths with controlled edges and straightness.
- Round rod or bar for electrical or general-purpose machining and fabrication.
- Custom copper shapes ordered from a complete section drawing and tolerance scheme.
Processing
- Control punching, drilling and bending to avoid burrs, cracks and contact-surface distortion.
- Protect contact faces from oxidation, oil, dents and mixed-metal contamination during storage.
- Specify plating, joint preparation and bolting as separate fabricated-system requirements.
Applications
- Switchgear, panelboards and power-distribution bus components.
- Electrical connectors, terminals and conductive machine components.
- General machined or formed copper bars, rods and shapes where B187 scope is suitable.
Selection
- Confirm that ASTM B187 Copper Bars actually covers the required product form and manufacturing route before comparing grades or quotations.
- Select alloy or grade and delivered condition from service, fabrication, section size and required property evidence; do not infer condition from a trade name.
- Require a written technical comparison and responsible-engineer approval before substituting another standard, alloy, condition or product route.
Procurement
- State ASTM B187/B187M-26, electrical bus or general-purpose duty, copper UNS and temper.
- State section dimensions/drawing, length, quantity, straightness, edge/corner radius and dimensional tolerances.
- Define conductivity/resistivity, tensile/hardness/bend or embrittlement tests and required surface/contact quality.
- Invoke B249/B249M where applicable and require inspection report, lot identity, protective separators and dry packing.