Isolation Transformers--Richard Gray or Torus?

Seems similar to what I experienced Terry. You're getting a no-load increase of +5-6V over nominal input. You have 116V in, so the secondary voltage is not an issue for you. Anyone with 120 VAC line will see 125V-126V on the secondary with a Plitron tranny -- more if they have high line like I do. I have tried other brands of balanced toroids with a 120V primary instead of 115V, and not experienced such an increase in no-load voltage.

Ever measured your output voltage ? The Plitron 2kVA isolation transformer they sell to DIYers (SKU # 8575-X0-02), has a 115V primary (I don't know why, with North American standard voltage being 120V?). I tried one many years ago. With my household voltage ranging betwen 122V-123V, I was getting up to 130V output from the Plitron, even when moderately loaded.