Silver Contact Alloys, Explained

Pure silver is superb at conducting electricity — and terrible at surviving as a contact. It's soft: under thousands of make-and-break cycles it deforms, wears, and welds. So the industry uses silver as a base and alloys it for hardness, arc resistance, and anti-weld behavior.

Silver keeps one more trick that justifies its cost: silver oxide remains comparatively conductive. Most metal oxides are insulators; a slightly oxidized silver contact still passes current. That's a big deal in a device that must work after sitting in a panel for thirty years.

AgNi (silver-nickel): the workhorse — good wear resistance and conductivity, common in breakers, contactors, and switches. AgCdO (silver-cadmium oxide): the legacy standard for excellent anti-weld and arc-erosion performance; largely phased out over cadmium concerns. AgSnO₂ (silver-tin oxide): the modern cadmium-free substitute, now dominant in new designs. AgW (silver-tungsten): extreme arc-erosion resistance for heavy-duty switching, plus silver-graphite variants for special applications.

Which one is in your breaker? For most sellers it doesn't change the outcome — but the era matters: older gear is more likely AgCdO, which brings the handling note below.

Legacy silver-cadmium-oxide contacts contain cadmium, which becomes a health concern if contacts are heated, ground, or melted during amateur recovery. Modern AgSnO₂ exists precisely to avoid this. If you're handling older electrical gear, don't heat, burn, or grind contacts — and treat any refining as a job for professionals with proper controls.

This is one more reason the "sell intact" path exists: it keeps the metallurgy problem with people equipped to handle it.

Here's a fact straight from the patent literature: electrical arcing gradually depletes silver in contacts, reducing breaker life. Every fault interruption and every heavy switching cycle vaporizes a microscopic layer. Industrial breakers account for this with replaceable contact assemblies; residential breakers just quietly age.

For sellers, the takeaway is simple: a breaker that's lived a hard switching life holds less contact metal than its factory spec — one more reason per-unit metal claims are unreliable, and one more reason to value the whole unit.

Photograph what you have — labels, nameplates, and overall quantity — and send it to Ironcrest for today’s offer. We buy electrical surplus nationally and coordinate pickup from your site.

Sell your breakers to Ironcrest →  |  Call or text 312-880-8174  |  Send photos →

Related reading: Do breakers have silver? →  |  Contactors & starters →  |  Metals in panels →

What does AgNi mean on a contact?

Silver-nickel: a silver alloy with nickel added for hardness and wear resistance. It's one of the most common contact materials in breakers and contactors.

Are old silver-cadmium contacts dangerous?

The cadmium in legacy AgCdO contacts is a handling concern mainly if the contacts are heated, ground, or melted — don't do any of that outside professional controls. Intact handling of old gear is not the risk scenario; amateur refining is.

What's the difference between AgCdO and AgSnO₂?

Both are silver-oxide contact materials with strong anti-weld behavior. AgSnO₂ (silver-tin oxide) is the modern cadmium-free replacement for AgCdO (silver-cadmium oxide), which has been phased down over cadmium concerns.

Does the alloy affect what my breakers are worth?

Rarely at the level of a seller's decision. Frame, brand, obsolescence, and condition drive value far more than which silver alloy is inside. The alloy matters to refiners, not to intact-unit buyers.

Where can I learn what alloy is in my specific breaker?

Manufacturer datasheets sometimes specify contact material for industrial frames. For most surplus lots, photograph the labels and ask — we'll identify the units, which is what actually sets the price.