Having to constantly refer to the equipment schedule for the wiring requirements for every piece of equipment can be time consuming.  And it will lend itself the opportunity to make mistakes.

I have found the following procedure to be helpful when taking off equipment.

1.  Start with the largest circuits for the equipment.
2. Take off all equipment circuits working your way until all that remain are the smallest circuits, ie: 3/4” 3 #12
3. Once all remaining circuits are the same size, you don’t have to keep referring to the equipment schedule, when you see an equipment connection, you know that it is the minimum size.
4. Approximately, 90% of the schedule will be the smallest size circuit.  ie: 3/4” with 3 or 4 #12 conductors.
5. Most equipment schedules are in column form.

Things to remember:

1. Be sure to check the raceway spec carefully.  GRC may be required in the electrical room and mechanical room.
2. Who provides the disconnect switches and starters, etc.
3. Who provides the VFDs.
4. If there are VFDs, be sure to read the wire and conductor spec carefully, special VFD cable may be required.
5. Sometimes specs require a factory representative for start-up and training classes for the owner’s representative of VFDs operation.
6. Controls maybe by others, but an empty conduit maybe the responsibility of the electrical contract.
7. Remember, a 60A piece of equipment on the roof will be more labor intensive that the same piece of equipment in the mechanical room.
8. Be sure you know who cares for the roof penetrations, pitch pockets, and roof sealing.  Sometimes roof warranties are required to be maintained.