Dryer Load Calculator

A dryer load calculator converts the connected nameplate rating of multiple dryers into a demand dryer load and the corresponding electrical current. The resulting amperes are used during preliminary branch-circuit or feeder load review, conductor and overcurrent-device evaluation, raceway planning, panel schedule development, and voltage-drop analysis.

The calculation begins with the installed dryer nameplate load. It then applies the selected Demand factor to account for the load basis being used for the installation. The calculator does not determine whether a particular demand factor is permitted; it applies the percentage entered on the screen.

For the values shown, three 5 kW dryers produce a connected load of 15,000 VA. Applying a 75% demand factor produces an 11,250 VA demand load. On a 240 V single-phase system, that demand load converts to 46.875 A.

Calculator Inputs

Field	Electrical purpose
Dryer nameplate load	The rated load of one dryer, entered in kW
Dryer count	Number of dryers included in the calculation
Demand factor	Percentage applied to the connected dryer load
System voltage	Nominal voltage used to convert demand VA to current
Phase	Selects single-phase or balanced three-phase current math

The Dryer nameplate load should be taken from the equipment nameplate or other verified equipment data. A nominal kW entry is converted to VA by the calculator’s load arithmetic for this workflow.

Use the actual quantity of dryers represented by the branch circuit, feeder, service segment, or design area being reviewed. Do not include unrelated laundry equipment, receptacle loads, HVAC loads, or motors unless they are separately included in the applicable load calculation.

Connected and Demand Load

The calculator produces two load values:

• Connected dryer load is the total installed dryer nameplate load before applying demand.
• Demand dryer load is the connected load after the entered Demand factor is applied.

\(\text{Connected dryer load (VA)} = \text{Dryer nameplate load (kW)} \times 1{,}000 \times \text{Dryer count}\)

\(\text{Demand dryer load (VA)} = \text{Connected dryer load (VA)} \times \frac{\text{Demand factor}}{100}\)

The demand result is the load value used for the calculator’s current conversion. It can also be carried into a larger feeder or service load worksheet when the dryer demand basis has already been established.

Dryer Current

The Dryer current output converts the calculated demand dryer load into amperes at the selected voltage and phase arrangement.

For single-phase equipment:

\(\text{Dryer current (A)} = \frac{\text{Demand dryer load (VA)}} {\text{System voltage (V)} \times \text{Phase multiplier}}\)

For the Single-phase selection, the displayed Phase multiplier is 1 x:

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

For balanced three-phase current math, the phase multiplier represents the three-phase relationship used in the denominator. This conversion assumes the calculated load is balanced across the phases; it does not establish phase balancing for an actual panel or feeder.

The calculated amperes support early conductor and raceway planning. Final conductor selection still requires ampacity evaluation using the applicable conductor material, AWG or kcmil size, insulation temperature rating, terminal rating, ambient-temperature correction factor, adjustment factor for current-carrying conductors, and the selected overcurrent protective device.

Calculation Example

Using the screen values:

Input or result	Value
Dryer nameplate load	5 kW
Dryer count	3
Demand factor	75%
System voltage	240 V
Phase	Single-phase
Phase multiplier	1 x

1. Calculate connected dryer load

\(5\text{ kW} \times 1{,}000 \times 3 = 15{,}000\text{ VA}\)

Connected dryer load: 15,000 VA

2. Apply the demand factor

\(15{,}000\text{ VA} \times 0.75 = 11{,}250\text{ VA}\)

Demand dryer load: 11,250 VA

3. Convert demand load to current

\(\frac{11{,}250\text{ VA}} {240\text{ V} \times 1} = 46.875\text{ A}\)

Dryer current: 46.875 A

That current value can be used to compare an initial feeder concept against available ampacity, estimate current-carrying conductor quantities for conduit fill, and begin a voltage-drop review over the planned conductor length.

Installation Verification

The calculation applies the entered demand factor and voltage only. The field design decision requires separate verification of the following conditions:

• The dryer nameplate rating, supply voltage, phase, and manufacturer installation instructions.
• The applicable load-calculation method and whether the selected Demand factor is valid for the equipment and occupancy.
• Whether dryers are supplied by individual branch circuits, a common feeder, or a panelboard with additional loads.
• Conductor ampacity after terminal limitations, insulation temperature rating, ambient correction, and adjustment for current-carrying conductors.
• Overcurrent protection, disconnecting means, equipment grounding conductor sizing, and panel capacity.
• Raceway fill, conductor derating, available fault current, and voltage drop where conductor length or starting performance warrants review.
• Balanced loading when using the balanced three-phase current option.
• Local amendments, project specifications, utility requirements, and the AHJ’s interpretation.