Removing the HV / 2nd Anode for Alignment?

[Jon1967us]

Noob question: Many TV alignment instructions say to remove, tape up and keep it away from the chassis prior to alignment. Why is this done?

Ive removed the anode lead from the crt many times to work on the set when off but never when the set is on. Makes me a little nervous to do that and how much electrical tape do I need to wrap around it to prevent arcing?