Commercial Load Diversity Calculator

A commercial load diversity calculation converts the sum of separately entered peak load blocks into a diversified block load. The result represents the estimated coincident kW demand when the load blocks are not expected to reach their individual peaks at the same time.

The calculator produces four planning values:

• Connected block load — the arithmetic total of Block A peak load, Block B peak load, Block C peak load, and Block D peak load
• Diversified block load — the connected block load after applying the Entered diversity factor
• Diversity reduction — the kW reduction between total connected load and diversified load
• Capacity margin — the remaining kW between Entered capacity and the diversified block load

The diversified kW is commonly used during preliminary commercial service, feeder, panelboard, switchboard, transformer, generator, and distribution-equipment load review. It can also support early conductor sizing, feeder routing, raceway planning, voltage-drop review, and capacity comparisons where a reviewed project diversity basis is already available.

A diversity result is expressed in kW, not amperes. Conductor ampacity, AWG or kcmil selection, overcurrent protection, terminal limitations, voltage-drop calculations, and raceway fill remain separate electrical design and installation decisions.

Related commercial load tools: Commercial Load Calculator, Continuous Load Calculator, and Feeder Load Calculator.

Load Blocks and Diversity Factor

The worksheet accepts four independent peak-load entries:

Input	Electrical meaning
Block A peak load (kW)	Peak demand assigned to the first commercial load block
Block B peak load (kW)	Peak demand assigned to the second commercial load block
Block C peak load (kW)	Peak demand assigned to the third commercial load block
Block D peak load (kW)	Peak demand assigned to the fourth commercial load block
Entered diversity factor (%)	User-supplied percentage used to reduce the summed block peaks to an estimated coincident demand
Entered capacity (kW)	Capacity used for comparison against the diversified block load

A load block may represent a tenant area, department, floor, retail bay, process area, equipment group, or another reviewed grouping used in the project load schedule. Each block should be entered as its peak kW value under the same basis used to establish the diversity factor.

The Entered diversity factor (%) is not calculated by the worksheet. It must come from a reviewed load schedule, meter profile, operating data set, engineering basis, or project-specific demand analysis. A 70% diversity factor means the combined coincident peak is assumed to be 70% of the sum of the individual block peaks.

The worksheet does not contain a hidden demand table, occupancy classification, equipment demand rule, motor rule, or compliance determination.

Calculation Method

The calculator first sums the four entered block loads:

\(\displaystyle \text{Connected block load} = A+B+C+D\)

It then applies the entered diversity factor:

\(\displaystyle \text{Diversified block load} = \text{Connected block load} \times \left(\frac{\text{Entered diversity factor}}{100}\right)\)

The resulting reduction is:

\(\displaystyle \text{Diversity reduction} = \text{Connected block load} - \text{Diversified block load}\)

Capacity margin is calculated against the entered comparison capacity:

\(\displaystyle \text{Capacity margin} = \text{Entered capacity} - \text{Diversified block load}\)

A positive capacity margin indicates that the entered capacity exceeds the calculated diversified block load. A zero result indicates that diversified load and entered capacity are equal. A negative result indicates that the diversified block load exceeds the entered capacity.

Calculation Example

Using the worksheet values:

Input	Value
Block A peak load (kW)	20 kW
Block B peak load (kW)	15 kW
Block C peak load (kW)	10 kW
Block D peak load (kW)	5 kW
Entered diversity factor (%)	70%
Entered capacity (kW)	40 kW

The connected block load is:

\(\displaystyle 20+15+10+5=50\text{ kW}\)

The diversified block load is:

\(\displaystyle 50\text{ kW}\times0.70=35\text{ kW}\)

The diversity reduction is:

\(\displaystyle 50\text{ kW}-35\text{ kW}=15\text{ kW}\)

The capacity margin is:

\(\displaystyle 40\text{ kW}-35\text{ kW}=5\text{ kW}\)

Result	Value
Connected block load	50 kW
Diversified block load	35 kW
Diversity reduction	15 kW
Capacity margin	5 kW

For a preliminary equipment review, the 35 kW diversified result is the load value compared with the 40 kW Entered capacity. The calculation shows 5 kW of remaining comparison capacity under the entered assumptions.

Electrical Design Use

A commercial diversity worksheet is useful when several load areas have substantial individual peaks but their maximum demand is not expected to occur simultaneously. Common examples include commercial tenant spaces, office floors, mixed-use common areas, retail suites, and non-coincident process groups.

The calculator supports a kW-level load review. Additional engineering steps may be needed before the result can be used for electrical equipment selection:

• Convert the applicable demand to current using the actual system voltage, phase arrangement, power factor, and equipment characteristics.
• Determine feeder or branch-circuit ampacity using the applicable load classification and installation conditions.
• Select conductor AWG or kcmil based on ampacity, conductor material, insulation temperature rating, terminal rating, ambient temperature correction factor, and adjustment factor for current-carrying conductors.
• Check voltage drop separately using conductor impedance, circuit length, load current, system voltage, and power factor where applicable.
• Verify raceway fill and physical routing independently; a diversified kW result does not establish conduit size, bending space, pull-box dimensions, or conductor pulling requirements.
• Review motor and equipment loads separately where starting current, largest-motor treatment, process duty, or other equipment-specific rules affect the feeder or service calculation.

A positive Capacity margin is a comparison result, not a determination that existing conductors, overcurrent protective devices, bus ratings, transformer capacity, or service equipment are acceptable.

Field Verification

Use the worksheet only with a diversity factor that has been reviewed for the actual operating pattern. A diversity factor derived from interval metering or an established project basis may not remain valid if tenant mix, operating hours, HVAC operation, process equipment, electrification loads, or future expansion changes.

For code-sensitive work, the arithmetic must be checked separately from the applicable electrical design and installation requirements. Confirm the governing load-calculation method, continuous-load treatment, conductor ampacity, terminal ratings, equipment listings, available capacity, and any requirements enforced by the AHJ.