What is the ESI threshold in Karnataka for ESI registration in Karnataka? Is it 10 employees or 20 employees?

Dear Members, What is the ESI threshold in Karnataka for ESI registration in Karnataka? Is it 10 employees or 20 employees?
Further, suppose an entity has crossed the threshold of 10 employees but none of the employees are drawing less than 21000. Is registration under ESI still required?

Further to my earlier query:
As per sec 1 - it is applicable to establishments employing 10 or more persons
But when we see definition of employee - it excludes employees drawing more than prescribed limit of wages
So in essence, persons drawing more than 21000 are not employees at all. So, there is no liability to register incase there are no eligible employees.
Suppose we conclude that the establishment has to be registered: should we file nil returns every month since there are no eligible employees.