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1) Sub-panels are never bonded. The neutral feeder terminates to the neutral bus bar and the green main bonding screw or main bonding jumper strap is never installed in a sub-panel. By not installing the main bonding screw or strap, this is how the neutral feeder remains isolated from the panel metal enclosure.
2) The grounding electrode conductor from the ground rods will land on a separate equipment ground bar that needs to be installed in the sub-panel. At the equipment ground bar, only the grounding electrode conductor and any bare copper grounds will land there.
3) At the neutral bus bar, only the neutral feeder and the individual white branch neutral conductors will land on the neutral bus bar. Never inter-mix neutrals and grounds on any sub-panel as it will not only result in a code violation, but will also create a potential safety issue.
4) Only at the main service are the neutral and grounds bonded together, but never on a sub-panel.
5) If the sub-panel feeder circuit is a new install, the feeder circuit is required by code to be a 4 wire circuit and not a 3 wire circuit. Sub-panel feeders for new installations require 2 hots, 1 neutral and 1 equipment ground.
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