Using 60000 psi as the tensile strength - the wire can handle ~25 lbs of weight in pure tension.
If you are hooking each end to a side of the mirror and then placing the middle on a hook that value goes up. The weight allowable is based on the angle of the wire (straight up and down is 50 lbs (2X tensile)).
At a 45 degree angle you're looking at ~ 35 lbs of load carrying capability.
I would make sure the mirror weighs less than 25 lbs since the tensile load is the breaking load is 25 lbs You'll want some margin. More if you live in an area with earthquakes.
You can also double the wire up (or use beefier wires) and put an anchor behind the mirror you're hanging so no wire is exposed.
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Using 60000 psi as the tensile strength - the wire can handle ~25 lbs of weight in pure tension.
If you are hooking each end to a side of the mirror and then placing the middle on a hook that value goes up. The weight allowable is based on the angle of the wire (straight up and down is 50 lbs (2X tensile)).
At a 45 degree angle you're looking at ~ 35 lbs of load carrying capability.
I would make sure the mirror weighs less than 25 lbs since the tensile load is the breaking load is 25 lbs You'll want some margin. More if you live in an area with earthquakes.
You can also double the wire up (or use beefier wires) and put an anchor behind the mirror you're hanging so no wire is exposed.
Good luck.
20 Gauge Steel Wire