Arc Flash Shields in disconnect boxes

I repair UL listed appliances that are sometimes directly wired into a fused or unfused disconnect box if they exceed 50A.

Sometimes I need to test the voltage on both sides of the knife switch. The new boxes seem to come with shields on the “hot” side, with little holes so that I don’t accidentally short things out with my probes. That would be okay except that my probes are not long enough to make contact with anything when I insert them in the holes.

So I have to remove the shield (usually very easy to thwart) and test as if it didn’t exist. I’m using a fluke meter with probes about 1.5″ long, so there is nothing wrong with my meter or probes. I was working with an electrician today and pointed this out and he said “Do not adjust your set. You are not doing anything wrong.”

And then he pointed out the obvious way to thwart the shielding.

So what gives? READ MORE