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Formula
Design watts = running watts + 0.25 × continuous watts.
Amps = design watts ÷ volts. Three loads are enough for a small schedule. Add a subtotal of the rest into one field if you have more nameplates.
Apply for financingElectrical load
Load calculator for watts and amps
This load calculator adds three loads, applies a 25 percent planning adder to the continuous watts you mark, and divides by voltage to estimate amps. It is a feeder planning sketch for equipment, not a service calculation under the electrical code.
Design watts
3,875W
Amps at your voltage16.15
Running watts3,500
Continuous adder25% on the continuous part
Planning estimate from the numbers you enter. Coverage, density, waste and price are assumptions, not a supplier quote or an engineering specification.
How it works
Continuous watts are counted at 125 percent.
Running watts are load A plus load B plus load C. Design watts replace the continuous portion with 1.25 times that portion. One thousand two hundred plus 800 plus 1,500 is 3,500 running watts. If 1,500 of those watts are continuous, design watts are 3,875. At 240 volts that is 16.15 amps. The continuous field cannot be larger than the total. This is the arithmetic electricians use as a check before a full load calculation. It does not apply demand factors, kitchen rules, or a dwelling service method. The HVAC load calculator is the BTU page. This one is watts.
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Example
1,200 W, 800 W, and 1,500 W, with 1,500 W continuous, at 240 V.
Running watts are 3,500. Design watts are 3,875. Amps are 16.15. Clear the continuous field to zero and the adder disappears.
03
Tips
Continuous means the load can run for three hours or more.
A welder that runs in short bursts is not the same as a heater that stays on. Mark only the part that is actually continuous. Nameplate watts already include the equipment. Do not also multiply by a power factor here.
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Equipment
The panel gear and the machines are the purchase.
Dengaro arranges financing for electrical equipment. The amp number is not a loan amount.
Important questions
Know what to expect.
Is this a whole-house service calculation?+
No. It adds the loads you type and grosses up the continuous part. A dwelling service calculation has its own demand factors. Use a qualified electrician for that.
Why 125 percent?+
A common planning rule counts a continuous load at 125 percent of its running watts. It is a check, not a permit by itself.
Can the three loads be on different voltages?+
The amp line uses one voltage. If the loads are not on that voltage, convert them to watts first, which the form already wants, and read amps only for the circuit whose voltage you typed.
Where is the HVAC load?+
Cooling BTU is on the HVAC load calculator. This load calculator is electrical watts.
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