Home Inspections are always an adventure!

I have written other posts on tinned copper wiring but thought it was a good time to revisit “Tinned Wires”.

Tinned wires usually can be found during home inspections in buildings up to the 1950’s when the transition was to thermoplastics, PVC began.

(tinned wires along with modern wires)

Why tinned? In some of the early wiring methods the insulator on the wire had vulcanized rubber insulation. The reason for vulcanized rubber was it didn’t absorbs moisture as readily and had better insulation properties than natural rubber, it was more elastic and more resilient.

But one of the issues with vulcanized rubber was sulfur. Sulfur reacts with copper creating the formations of copper sulfides, corrosion. Any corrosion degrades the wire and causes loss of performance. So tinning the wires help prevent this chemical reaction. Another benefit of tinning was it made the wire easier to strip and solder.

Copper is one of the best electrical conductors. Silver is a better conductor but comes at a much higher cost. Copper being that it is easy to machine makes it an ideal material for making electrical wire. Silver is commonly used in the contacts in circuit breakers, motor starters, and in electrical conductor plating.

Yet copper and silver both suffer from corrosion in certain environments and a higher probability of equipment damage and/or failure in certain environments.

In comes tin. Tin is the 49th most abundant element, with Copper being the 26th most abundant element and Silver is the 65th most abundant element.

 ( Electron Configuration of Tin)

Tin, having the largest number of stable isotopes (10) in the periodic table, is a extremely stable material. This gives tin a very good resistance to corrosion at a relatively low cost making Tin the preferred choice as a corrosion resistant coating on other metals.

Many electrical manufacturers still use tinned conductors and electrical equipment in corrosive environments. That is why it is still a common wire in marine applications.

“If you think it's expensive to hire a professional to do the job, wait until you hire an amateur.”

Red Adair

NCW Home Inspections, LLC  is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…  

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