I have 200 amp service coming in at the first level of the house. I am finishing my basement and want to add a sub panel. There has been quite a confusion about combining the ground and neutral together (sub panel or main panel). I have asked at Home Depot and Lowe's and couple of other 'smart' guys at work. What I have been able to understand or gather from all the mixed information is that the ground and neutral should be combined (tied together) in the Main Panel where the service comes in. My servcie comes under ground to the meter and enters the main panel (this is where I believe Ground and Neutral are combined). Also, the ground and neutral should be kept separate in the sub panel. I am using a #6-3 wire (2 hot, 1 ground, 1 neutral) to run to the sub panel from the main panel and put a 60 amp double pole CB in the main panel. There would 4-6 circuits in the sub panel of 15 amps. The sub panel is cutler hammer br1224l125 125 amp in which I have two separate neutal and ground bars that are connected together with a shielded metal strip. Why would it differ if the main panel has both the ground and neutral tied together and then separated in the sub-panel, is it NEC code or some electrical law. I would really appreciate your expert advise in clearing these doubts.

Just had this question, here are some answers:

https://www.askmehelpdesk.com/electrical-lighting/why-do-we-bond-neutral-ground-breaker-box-271331.html

Note, the connection of the neutral and all grounding is at the Main Service Disconnecting Means, AKA Main Breaker. If the Main Panel, does not have the Main Breaker, then it too does not have the neutral and ground connected, only in the enclosure that actually contains the main breaker.