Demand Factor Calculator

A demand factor calculator converts a known Connected load into an Estimated demand for preliminary electrical load review. The result is useful when a reviewed load method has already established a demand percentage and the load must be carried forward into a feeder, service, panel schedule, voltage-drop, or equipment-capacity workflow.

Connected load is the total nameplate or calculated load before demand is applied. Estimated demand is the portion expected to be used after applying the entered demand factor, plus any separately identified fixed allowance. The calculator also reports the resulting Diversity allowance, which shows the difference between connected load and estimated demand.

This mode performs transparent entered-factor arithmetic. It does not select a demand factor, apply a demand table, determine feeder or service load, or make a final code compliance decision.

Calculation Inputs

Field	Electrical use
Connected load	Total load being screened, entered in VA
Entered demand factor	Demand percentage from the reviewed load method
Fixed allowance	Additional VA included outside the percentage-based portion of the calculation

The Connected load should represent the load basis being evaluated consistently. For example, if the demand factor was developed for a group of branch-circuit loads, the connected load should include only that same group—not unrelated loads from another panel, feeder, motor lineup, or service section.

The Entered demand factor is not an ampacity adjustment factor, conductor correction factor, or voltage-drop multiplier. It is a load-estimating percentage applied to connected VA. It must come from the applicable reviewed design method, engineering basis, load study, project requirement, or code calculation performed separately.

A Fixed allowance increases estimated demand directly. It is not reduced by the entered demand factor. It may represent a load component that is intentionally added after the factored-load calculation.

Demand Load Formula

The calculator uses the following formulas:

\(\displaystyle \text{Factored load} = \frac{\text{Connected load} \times \text{Entered demand factor}}{100}\)

\(\displaystyle \text{Estimated demand} = \text{Factored load} + \text{Fixed allowance}\)

\(\displaystyle \text{Diversity allowance} = \text{Connected load} - \text{Estimated demand}\)

The calculator also reports the Effective demand factor:

\(\displaystyle \text{Effective demand factor} = \frac{\text{Estimated demand}}{\text{Connected load}} \times 100\)

Because Fixed allowance is added after the percentage calculation, the Effective demand factor can be greater than the Entered demand factor. If the allowance is large enough, Estimated demand can also exceed Connected load, producing a negative Diversity allowance. That outcome may be mathematically valid for the entered values, but it should be reviewed against the intended load method.

Calculation Example

Using the entered values:

Input	Value
Connected load	50,000 VA
Entered demand factor	55%
Fixed allowance	2,500 VA

First, calculate the factored portion of the connected load:

\(\displaystyle 50{,}000 \text{ VA} \times \frac{55}{100} = 27{,}500 \text{ VA}\)

Then add the fixed allowance:

\(\displaystyle 27{,}500 \text{ VA} + 2{,}500 \text{ VA} = 30{,}000 VA Estimated demand\)

The reported diversity allowance is:

\(\displaystyle 50{,}000 \text{ VA} – 30{,}000 \text{ VA} = 20{,}000 VA\)

The effective demand factor becomes:

\(\displaystyle \frac{30{,}000}{50{,}000} \times 100 = \text{60\%}\)

Although the Entered demand factor is 55%, the Fixed allowance raises the total Estimated demand to 30,000 VA, or 60% of the Connected load.

Use in Electrical Load Workflows

Estimated demand in VA is commonly carried into subsequent calculations after the applicable load method has been established. At the system voltage and phase arrangement being evaluated, VA can be converted to calculated current for a feeder, branch circuit, or service review.

For a single-phase system:

\(\displaystyle I = \frac{VA}{V}\)

For a three-phase system:

\(\displaystyle I = \frac{VA}{\sqrt{3} \times V}\)

The resulting current may then be evaluated with conductor ampacity, terminal rating limitations, insulation temperature rating, continuous-load treatment, overcurrent protective device selection, voltage-drop review, and available equipment ratings. Raceway fill and bending layout are separate physical installation calculations; they are not determined from estimated demand alone.

For example, a 30,000 VA estimated demand produces different current values at different system voltages and phase configurations. The VA result must therefore remain tied to the actual distribution system before selecting AWG or kcmil conductors, conduit size, disconnects, panelboards, transformers, or protective devices.

Field and Code Limits

The calculator applies only the values entered into Connected load, Entered demand factor, and Fixed allowance. It does not determine whether a demand factor is permitted for a particular occupancy, equipment type, branch circuit, feeder, or service.

Verify separately:

• The load inventory and whether Connected load includes the correct equipment, utilization loads, motors, heating, receptacles, lighting, and noncoincident loads.
• The source and applicability of the Entered demand factor.
• Any fixed load that must be included at 100% rather than included in a generalized demand treatment.
• Required treatment of continuous loads, motor loads, largest-motor components, noncoincident loads, and equipment-specific load rules.
• Feeder and service calculation requirements applicable to the installation and the adopted electrical code.
• Conductor ampacity after applicable adjustment factor and correction factor calculations, including current-carrying conductors, ambient temperature, terminal rating, and insulation temperature rating.
• Final approval requirements of the AHJ, project engineer, utility, and equipment manufacturer.

Use the Estimated demand result as a documented arithmetic input to the larger electrical design or load-calculation workflow, not as a substitute for the applicable load calculation or final equipment sizing.