In a high voltage term cabinet with a fused switch, what does the term BALL STUD refer to ? 1

[bdn2004]

I'm looking at a single diagram for a large industrial plant. The transformer primary termination sections have a fused switch. Every one of the them it calls out the location of the BALL STUD. It appears it's either on the line side of the high voltage fuse or the load side. What is this and what is it used for? And why would you go to such trouble to note it's location?

 

[wroggent]

Probably for grounding

http://www.morek.eu/product-category/accessories-for-switchgears/polyamide-spacing-insulators/

 

[JJ_Roy]

Used for grounding within a limited space

https://www.hubbell.com/hubbellpowe...-Bonding/Mechanical/Clamps/Ball-Stud/c/561278