@Button Pusher has the correct answer. We call that puddy duct seal.
Take that duct seal and pack it thoroughly around the service wires coming in from the meter base to the breaker panel. (take the rag out first lol)
Duct seal is non conductive and listed for the purpose. But..over time if it's exposed to heat or elements, it will dry up and start to crack. And those service wires will get warm.
To prevent cracking, after you pack in the duct seal, take clear silicone and your finger and cover the duct seal with it. It'll be there long after you aren't.
Ideally, this should be done from the meter base side. Don't do this please. I've cut hundreds of those little tags off the meter base that the power company uses to 'lock out' the meter base. That's not the issue. The meter base is not fused, meaning it will smoke you if you get caught up in it. This should only be done by a competent electrician that knows what to avoid as the meter base is a very confined area to work in.
If you're comfortable working in your breaker panel while it's hot, I'd still recommend using cardboard to cover the energized breakers and bus bars. It's easy to get an elbow on something.
But this is something that you can do if you're careful. Rule #1..don't get shocked! If you would rather use an electrical contractor, this would be a minor service call charge of less than $100.