Free Electric Load Calculator

Free NEC Standard Method Single Family Residential – Electric Service Entrance Load Calculator


What is this?

Enter plain numbers in cells without text or labels. If you leave any cells empty they will be calculated as zero.

Total Square feet of dwelling

Total # of Small Appliance Branch circuits (must be at least 2). If you have gas appliances which require a 120v branch circuit include them here.

Total # of Laundry Branch circuits (must be at least 1)

Fastened in place Electrical appliances – Do not include gas appliances in this section. Use nameplate rating in volt-amps or watts – If appliance is rated in amps then volt-amps = amps * volts. Voltage value is either 120 or 240. So, for a 120 volt appliance which is rated at 15 amps, 120 volts * 15 amps = 1800 volt-amps.

Total # of water heaters

Volt-amp rating of water heater

Total # of trash compactors

Volt-amp rating of trash compactor

Total # of dishwashers

Volt-amp rating of dishwasher

Total # of disposals

Volt-amp rating of disposal

Total # of microwave ovens

Volt-amp rating of microwave oven

Total # of range hoods

Volt-amp rating of range hood

Other fastened in place appliances – use this section to define things like spas which aren’t specified above.

Total # of other fastened in place appliance #1

Volt-amp rating of other fastened in place appliance #1

Total # of other fastened in place appliance #2

Volt-amp rating of other fastened in place appliance #2

Total # of other fastened in place appliance #3

Volt-amp rating of other fastened in place appliance #3

Total # of clothes dryers

Volt-amp rating of clothes dryer (must be at least 5000)

Total # of Ranges

Volt-amp rating of Range

Total # of Ovens – Note: If there is a range, and no additional oven then don’t put anything here.

Volt-amp rating of Oven

Total # of Cooktops – Note: If there is a range, and no additional cooktop then don’t put anything here.

Volt-amp rating of Cooktop

Total # of Other cooking appliance over 1750 volt-amps

Volt-amp rating of Other cooking appliance over 1750 volt-amps

Volt-amp rating of Larger of Heating OR Air conditioning system – always include air handler. For heat pump include compressor and the maximum amt of electrical heat that can be energized while compressor is running.

Volt-amp rating of Largest Single Motor (usally the HVAC compressor or air handler motor)

Service voltage is assumed to be 240


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What is this Load Calculator for? Electricity is delivered to your home by the Service Entrance which is sized based upon calculations dictated by the NEC and the local codes authoritys along with the electric utility provider. Most jurisdictions use the NEC standard method calculations without significant modification. There is nothing about the calculations which are difficult to do by hand with only a pencil and calculator, but each calculation has quite a few steps, and can take a while to do – especially if you aren’t familiar with it.

This automated calculator makes it much quicker and easier to try different scenarios which can be quite useful if you’re planning a remodelling or addition project. Sometimes using more energy efficient fixtures appliances, and HVAC equipment along with upgraded insulation and weather proofing can help you to avoid retrofitting a new larger service entrance and significant expense.

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13 thoughts on “Free Electric Load Calculator”

  1. We are looking for clarification on your electric load calculator. We have an all-electric house which currently has a 200 amp service. But an electrician has told us we are approaching the upper limit of our service.

    When we use your calculator, it tells us our service should be larger than 200 amps.

    I would like to email someone to verify the numbers I used and whether or not the answer is correct.

  2. Jeff, it sounds like you either need to reduce your load or bite the bullet and get a bigger entrance. The ultimate authority is your local electrical inspector and engineering department.

  3. for residential load calculation is pool motors and equipment fall under appliances? if not where do i put those loads?

  4. Because those things which plug into “convenience outlets” are included in a standard calculation which is mostly based upon square footage.

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    My site addresses a lot of the same topics as yours and I feel we could greatly benefit from each other.
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  6. I am running service to an out building on my property; it currently only has a 15 amp feed to it. It is a shop and I plan on having 220 for a welder that I do not have yet, a compressor (small size), 2 pumps for the septic system @ 20 amps each, and then some basic outlets and lights, 2 breakers for that. The building is less than 400 SF.
    I want to run a 50 amp breaker in the control panel in my house to the building which is 150′ away. I am not sure how to use your calculator since it is really designed for a home. What I am trying to determine is the gauge of wire I need to run.
    Thanks for any help you can offer,
    John

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