Electrical Service Load Calculator

Background.

Electrical Service Load Calculator supports a concrete decision: use it to apply entered demand factor and planning margin to connected load for a preliminary service-load figure. The result needs one precise interpretation: connected nameplate load is not automatically the NEC calculated load because Article 220 applies category-specific demand and diversity rules. The selected relationship is “design load = connected load × demand factor × (1 + design margin).”

The editable entries are connected or calculated load, applicable demand factor, design margin, system voltage or design divisor. Use values from the document or measurement that governs this electrical service load question; the defaults are only the worked fixture below. This single factor cannot size a service or conductor; local code edition, dwelling method, continuous loads and utility rules govern. The electrical service load calculation does not infer that fact from the other entries.

NFPA 70, National Electrical Code 2023; load calculations, feeders and continuous loads documents the convention or governing rule used here. The electrical service load output is a transparent scenario under those facts: it does not manufacture an unentered market price, professional determination, carrier quote, legal eligibility finding or locally adopted code value.

What is electrical service load calculator?

Electrical Service Load is the relationship behind this decision: connected nameplate load is not automatically the NEC calculated load because Article 220 applies category-specific demand and diversity rules. On this page it means design load = connected load × demand factor × (1 + design margin). This single factor cannot size a service or conductor; local code edition, dwelling method, continuous loads and utility rules govern; that is the line between the reported quantity and a broader electrical analysis.

How to use this calculator.

1. 01Confirm that “design load = connected load × demand factor × (1 + design margin)” matches the electrical service load convention you need.
2. 02Replace the fixture values for connected or calculated load, applicable demand factor, design margin, system voltage or design divisor with dated values from the governing record.
3. 03Keep all currencies, measurement units and time periods on the same basis before calculating.
4. 04Read design load together with this boundary: This single factor cannot size a service or conductor; local code edition, dwelling method, continuous loads and utility rules govern.

The formula.

The calculation uses design load = connected load × demand factor × (1 + design margin). In this electrical service load model, the entered terms are connected or calculated load, applicable demand factor, design margin, system voltage or design divisor. Connected nameplate load is not automatically the NEC calculated load because Article 220 applies category-specific demand and diversity rules, which is why the relationship is presented under this name rather than as a universal alternative. This single factor cannot size a service or conductor; local code edition, dwelling method, continuous loads and utility rules govern. Calculations keep full decimal precision through the relationship and round only the returned display values.

A worked example.

Frequently asked questions.

References& sources.

1. [1]NFPA 70, National Electrical Code 2023; load calculations, feeders and continuous loads. Retrieved 2026-08-07. access: open unless marked otherwise.
2. [2]International Code Council. 2024 International Residential Code (IRC). Retrieved 2026-08-07. independence: primary; access: open.
3. [3]U.S. Occupational Safety and Health Administration. Electrical — standards and hazards. Retrieved 2026-08-07. independence: secondary-check; access: open.
4. [4]U.S. Department of Energy. Energy Saver. Retrieved 2026-08-07. independence: primary; access: open.
5. [5]U.S. Energy Information Administration. Electric power monthly — average retail price of electricity. Retrieved 2026-08-07. independence: secondary-check; access: open.