Start with the right calculation basis
Sections 120.1–120.5 frame branch-circuit, feeder and service load calculations and point to equipment rules elsewhere in the NEC. Motors, HVAC equipment, electric heat and appliances can have additional requirements. Record the nominal voltage, equipment ratings and floor-area basis before applying a demand factor.
Article 120 does not automatically add 125% to every continuous load in the load calculation. Conductor and overcurrent-device sizing are separate checks under their applicable rules. See continuous load vs demand.
Noncoincident loads need evidence
Section 120.6 treats loads that are unlikely to run together differently from loads prevented from running together. The “unlikely” basis applies to feeder and service calculations; a branch-circuit calculation needs a basis that prevents simultaneous operation. A heating/cooling label alone is not proof: reheat, defrost and auxiliary heat can overlap with compressor operation.
Power control system scope
Section 120.7 permits a qualifying power control system (PCS) in the calculation when controlled and uncontrolled loads are both accounted for. Under §120.7(B), the 80% limit concerns the overload-control setting for the monitored circuit’s overcurrent device, established by a qualified person. It is not a blanket 80% rule for every PCS parameter. Show which circuit is monitored, which loads are controlled, and the equipment’s applicable Article 130 Part II basis.
Field check
- Inventory connected, proposed and managed loads, including loads that can overlap.
- Record why each claimed noncoincident pair cannot or is unlikely to run together, as applicable.
- For a PCS, confirm the monitored OCPD, control settings and the path for uncontrolled loads.
Show on drawings
Put the load inventory and calculation method on the electrical calculation sheet. Show operating interlocks or control sequences and the PCS monitored point on the one-line and controls notes. Reconcile the result with the current equipment schedules. For an existing service, see #033 on measured existing demand.
Code basis and applicability
Educational reference to the 2026 NEC Sections 120.1–120.7. Check the complete NFPA 70 text, the locally adopted edition and amendments, the authority having jurisdiction, and selected equipment instructions before project use. This page is not a project-specific load calculation or professional code determination.