Yea, I know what that's like. I've had to venture into the world of CAT III now and then. When it comes up, something is going on and I will need something more than a basic meter so I take that HIOKI with me. I'm not an electrician but have some idea what I am doing, and I use clamps so fairly low risk. Also, the voltages/currents are fairly low. The first person I want to talk to is their master electrician. I've had some pretty insightful conversations with a few of them, especially if I keep them in the loop while I am working.
I had HIOKI come in and demo the first meter I started using. They left it with me to try out. We surge tested it for real, not these little transients that I show in my home videos. They come at a price but I do like their products. Then again, I tried to contact them from my home email account and could never get them to respond.