Hello what is the best way to cover plaster wall holes about 3" big

Can you see wood lath where the plaster was?

Most of the holes are in the ceiling.I rewired my house and I had to do a lot holes to run the wired. The ceiling is halo. Tank you

I just went through this. I cut and fit pieces of lathe strip into the holes, then used a quick-setting patching plaster (Web Coat?). First plaster application was a rough fill; after this dried I went back for a final coat. Some sanding may be necessary, depending upon how well you finish the final plaster application with the trowel.

In addition to the above comment, try wetting the old plaster before you apply the new topping, this allows the old to retain a little more moisture during drying time, lessening the cracking.

Ken

I just went through this. I cut and fit pieces of lathe strip into the holes, then used a quick-setting patching plaster (Web Coat?). First plaster application was a rough fill; after this dried I went back for a final coat. Some sanding may be necessary, depending upon how well you finish the final plaster application with the trowel.
What is web coat

Web Coat is a fast setting (15-20 minute working time) plaster. I bought it from my local paint store, but I see that Lowe's and Depot sell other brand names of the same type of thing. Mix with water, and it's kind of like drywall joint compound, but sets faster and harder.

Sheetrock 20 is another. Be careful when wetting the old plaster. Some the old lime based plasters have a tendency to self-destruct when they get wet.