Copper Supply & Fabrication in Fresno, CA

C101 is oxygen-free electronic (OFE) copper — the highest-purity, highest-conductivity grade, with oxygen removed so it performs reliably even in high-temperature or hydrogen-bearing service and in demanding electronic applications. Use it where maximum conductivity and purity matter or where the part will be brazed or used in vacuum or hydrogen atmospheres that would embrittle ordinary copper. C110 is electrolytic tough pitch (ETP) copper, the most common high-conductivity grade — about 100 percent IACS, excellent for busbars, grounding, wire, and general electrical work, at lower cost than C101. It's the default for most Valley busbar and connector work. The caution with C110 is hydrogen embrittlement: its small oxygen content can cause cracking if it's heated in a hydrogen atmosphere (such as some brazing furnace cycles), which is precisely when you'd switch to C101. Tellurium copper (C145) adds a small amount of tellurium that makes the copper free-machining — dramatically improving machinability while retaining around 90-plus percent IACS conductivity. It's the grade for high-volume turned and screw-machine parts like connectors, contacts, and fittings, where pure copper's gummy machinability would otherwise wreck productivity.

Pure high-conductivity copper (C101, C110) is soft, ductile, and gummy — it forms and bends beautifully but machines poorly, tending to smear, build up on the tool, and produce a rough finish. That's fine for busbars, which are typically sheared, punched, formed, and drilled rather than precision-machined. But for parts with significant turning or milling, pure copper's machinability is a real problem, which is exactly why tellurium copper exists. Switching from C110 to C145 for a high-volume machined connector can transform cycle time and finish while sacrificing only a few points of conductivity. For busbar fabrication specifically — the bread and butter of Valley copper work — the operations are cutting (shear, saw, or laser), CNC punching or drilling of bolt-hole patterns, bending or forming to route around equipment, and edge finishing. Tolerances on busbar hole patterns matter because they must align with mating terminals, so specify hole locations precisely. Where copper is brazed or soldered into assemblies, joint design and the grade's behavior under heat both matter — another reason to confirm C101 versus C110 when furnace or hydrogen brazing is involved.

Bare copper oxidizes, and copper oxide is a poorer conductor than copper, so connection surfaces are often plated to maintain low contact resistance over time. Tin plating is common on busbars and connectors — it resists oxidation, stays solderable, and keeps bolted-joint resistance stable. Silver plating goes on high-performance contacts where the lowest possible contact resistance is required. Nickel plating provides a harder, more durable barrier and is used as an underplate or where wear resistance matters. When you spec a copper electrical part for a Fresno solar or switchgear application, decide the plating up front based on the connection environment and expected life. The other finishing concern is the integrity of bolted electrical connections themselves. Busbar joints rely on adequate contact area, proper surface preparation (clean, often plated, sometimes with joint compound), and correct bolt torque to keep resistance low and avoid hot spots that degrade over time. A well-made copper part can still fail in service if the connection design or assembly is wrong. When you source busbars and connectors locally, give your fabricator the current rating, the mating-terminal details, the plating requirement, and the connection method — that lets them deliver a part that performs electrically, not just one that fits.