I am installing a 125 Amp Sub panel in a detached shed approximately 100' from the house. The subpanel has a 100 amp main breaker in it and I have a 100 amp breaker that will go in the main house panel to feed it. I will be using #4 copper THHN for my 2 hot conductors and neutral conductor and a #6 for my grounding conductor. My question is, do I need to install a ground rod at the sub panel and does the subpanel neutral bar need to be bonded with the grounding electrode conductor. I am thinking I do not need the ground rod or nor do I need to bond the neutral and grounding electrode together, but I am just not sure. Can someone please clarify this for me?

Yes, for the panel in the shed a ground rod is necessary at the shed, AND the neutral shall NOT be bonded to the equipment ground in the shed panel.

This is outlined in the NEC Section 250.32 Two or More Buildings Supplied from a Common Service(A) & (B)1. of the NEC (http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=70).

TK, thank you so much for verifying that for me. My mind is now at ease...

No problem, have a great time pounding away, watch the hand holding the rod.