Why does the bucket in a bucket truck need to be solid to maintain grounding?

Question

I’m watching this arborist on YouTube and they have a truck with a bucket on an arm so they can reach heights without climbing. On/after a rainy day the bucket will accumulate water and they mentioned they can’t drill a hole to drain because it will compromise the grounding.

My understanding of grounding/electricity doesn’t explain this. Can someone help me understand why this would make a difference?

Edit: I get it, I/he should have said “electrical isolation” instead of “grounding”. Either way, a hole allowing a stream of dirty water seems to be the answer here. Thanks 🙂

In: Physics

Answer 1

Drilling a hole will add an exit point for electricity. Without the hole, electrical charges will have to follow the bucket, then the arm and end with the truck, thus further from the person in the bucket.