At how many schools may I legally work?

I would like to get some info on what the law says about the number of places one may legally work. I would also like to be able to quote something official from the MOE/government regarding this. Please help.

What sort of visa do you have?

I came in with a single entry visa, but got my ARC afterwards.

I believe you are allowed to have up to 3 work permits backing up a single ARC. I currently have two.

Edit: Each school has to provide you with the minimum amount of hours required which is, I believe, 12 or 13 hours per week. They are not cumulative as in you can’t get 1/2 the hours at one school and the other half with another. That’s why they will not issue a fourth work permit because that would technically take you up to nearly 50hrs/week.