Hi,
As stated in Article 250 of NFPA 70, different types of earthing (intrinsically safe, instrument earth(non IS) and protective earth) shall be connected together (apparently) at one point.
But I didn't find any solution to avoid one earth current or voltage, affecting other earthing system in any standard.
If I remember correctly, earth bonding is not a common solution in all countries.
With all that being said, here are my questions which I kindly request your help:
1. How to protect for example intrinsically-safe earth system from protective (safety) earth currents when these two earthing systems are connected together? What's the reference standard and section for the solution provided?
2. If in some other companies, earth bonding is not allowed, what is the reference standard and section?
3. What is pros and cons of each solution?

With many thanks,
Sadeghinia