My main elect panel in the house has a common neutral/ground bar and not separate bars. If I run from this panel to a sub panel in a detached pole barn and attach the two hots for 240V and one neutral that is connected to the neutral/ground combination bar in the main panel, am I grounded properly? Would I also need a ground rod in the pole barn and if so, does it get connected to the neutral bar or is it grounded to the sub panel itself?
Larry, I can relay what is required in our area. For each and every premise now is allowed one service panel only; thus requiring only three wires to feed. All other panel on the premise are required to be fed, for the sake of safety, with four wires. These include two wires as phase conductors, one neutral and one ground. Additionally, all panels that are located in a separate building require ground rods, no longer just one ground rod but two separated by 6'. In the service panel the neutral and grounding all come together at the neutral bus bar. The subsequent panels must have all neutrals and grounds separated. Good Luck; PCL