Originally Posted By: jsmith3
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Originally Posted By: Greg Fretwell
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He can double up the grounds on most panels, some even 3 per lug, read the label.
The neutrals all need to be one per screw
Originally Posted By: Greg Fretwell
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408.21 Grounded Conductor Terminations.
Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor.
Handbook commentary
In accordance with their listing and the requirement of 110.14(A), conductor terminations are suitable for a single conductor unless the terminal is marked or otherwise identified as suitable for more than one conductor. This requirement applies only to the termination of grounded conductors in panelboards. The use of a single termination point within a panelboard to connect more than one grounded conductor or to connect a grounded conductor and an equipment grounding conductor can be problematic when it is necessary to isolate a particular grounded conductor for testing purposes. For example, if the grounded conductors of two branch circuits were terminated at a single connection point and it was necessary to isolate one branch circuit for the purposes of troubleshooting, the fact that the circuit not being tested remains energized can create an unsafe working condition for service personnel disconnecting the grounded conductor of the circuit that is being tested. There are panelboard instructions that permit the use of a single conductor termination for more than one equipment grounding conductor. See 408.20 for the requirements on panelboard terminations for grounded and equipment grounding conductors.
Originally Posted By: jsmith3
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Thanks Greg, what I do not understand about the way this panel was wired is all the grounds and neutrals go to the right side when there is an empty buss on the left, it would have been a cleaner job and easier to trace later had the grounds and neutrals been ran on the same side as the breakers.
Originally Posted By: Greg Fretwell
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If he left a busbar unused and double lugged the other one his technique is certainly open to critique.
The polite way would be to use the one connected to the service neutral for all the white wires and use the one bonded to the can for the bare and green wires. I like backing up the green screw with a #4 copper but that may just be me.
If at a later date, this were to become a sub panel, all they have to do is remove the green screw (and any other bonding jumper).
Even if this never happens it is still a neater panel.
Originally Posted By: roconnor
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Note that the requirements for each neutral to be on a separate terminal (408.21) is new for the 2002 NEC. The requirement was previously only in the UL panel standard (UL-67), only indirectly referenced in the NEC.
Some didn't see any direct restriction in the elec code, so they figured the double lug neutrals wasn't a big deal. It's a common defect you will see in panels ... 
--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong