2012/01/04 at 6:14 pm #10745elec masterParticipant
Residential Load Calculation is designed to be simple and yet flexible. Follow along as I explain the uses for entry cell.
How to use?
Holding your cursor over any cell with a RED marker in the upper right reveals comments or helps to guide you thru the data entry. Validation rules have been added as a helpful feature. Try entering 1 for small appliance circuit, the validation is set for 2 minimum, by clicking on cell “ E6” the code article pop-up window shows the corresponding article. If the window is in your way just pull it to the side and keep entering. Press the tap button to move from entry cell to entry cell.
To print go to the top of the page, next to file, edit, is view from there go down to custom views, you will find “calc w/ pool” and “calc no pool”. Select the one you want to print and press the print button.
Residential Load Calculation spreadsheet manual:
Check the box in cell D6 next to the title of the sheet to use the “optional calculation ART 220.82” instead of the “standard calculation ART 220.42 THRU 220.55”
first :User Info. Worksheet
1- Enter the required information in the User Info. Worksheet As follows:
City, state, Zip code
second:Residential Calculation worksheet:
Step (1): Article 220.42 & 220.52
First: input data
1- For General Lighting load: Enter square foot/square meter living area by selecting from the drop down box, As per NEC 220-3 (b) the floor area shall be computed from the outside dimensions of the dwelling unit. For dwelling units, the computed floor area shall not include open porches, garages, or unused or unfinished spaces not adaptable for future use.
Note: a minimum square area permitted = 1000 square foot and The demand factors listed in table 220-42 (220.82(1) for optional method) shall apply to that portion of the total branch-circuit load computed for general illumination. They shall not be applied in determining the number of branch circuits for general illumination.
2- For Small Appliance: as per NEC 220-11(c) (1) which need “two or more 20 ampere small appliance branch circuits shall be provided for all receptacle outlets specified by section 210-52 (b) for small appliance load”
Note: Minimum of (2) circuits are required for small appliances
3- For Laundry circuit: as per NEC 220-11(c) (2) which need “at least one additional 20 ampere branch circuit shall be provided to supply laundry receptacle outlet(s) required by section 210-52(f)”
Note: Minimum of one circuit is required
Second: output data
1- For General Lighting load: as per NEC 220-12 which need Lighting load for dwelling unit(s) that a unit load not less than 3 VA shall constitute the minimum lighting load for each square foot of floor area
2- For Small Appliance: as per NEC 220-52(A) which need that the load shall be computed at 1500 VA for each 2-wire small appliance branch circuit required by NEC 220-11(C)(1)
3- For Laundry circuit: NEC 220-52(B) A load not less than 1500 volt-amperes shall be included for each 2-wire laundry branch circuit installed as required by 210.11(C)(2)
4- For General load sum for lighting, small appliances and laundry loads: This is the sum total of (1) general lighting (living area square footage times 3 watts) , (2) each small appliance circuit @1500 watts each and laundry circuit @1500 watts
5- For General demand load sum: General load sum= First 3000VA @ 100% demand + Next 117,000 @35% demand +Reminder @ 25% demand
Step 2: Article 220.50 & 220.51
A check box is shown for selection between making calculations for (A/C Condenser and fixed space heating) or (Heat pumps with concurrent supplementary heating)
First case: (A/C Condenser and fixed space heating)
1- Select the A/C Condenser cooling tons from the drop down box #1 and you will get the electrical load in VA for A/C condenser.
2- Select the fixed space heating (AHU) KW from the drop down box #2 and you will get the electrical load in VA for both strip heater and blower loads.
3- Select the quantities for A/C Condenser and/or fixed space heating AHU.
1- Heating load in VA (heating Load =(space heat x demand factor + 100% (fan blower) )
2- Cooling load in VA (the blower fan from the AHU is included in this value)
3- Greater of Heating load @100% VS cooling load @ 100%
Second case: (Heat pumps with concurrent supplementary heating)
1- Select the Heat pump tonnage from the drop down box #1 and you will get the electrical load in VA for Heat pump.
2- Select concurrent supplementary heating KW from the drop down box #2 and you will get the electrical load in VA for both strip heater and blower loads.
3- Select the quantities Heat pumps with concurrent supplementary heating.
1- Heating load in VA (heating Load =(space heat x demand factor + 100% (fan blower) + 100% heat pump )
2- Horse power load in HP
3- Heating load @100%
To read more and download the Residential Load calculation spreadsheet, please visit the below links:
Electrical calculations spreadsheets at link:
Residential Load Calculations Spreadsheet – Part Two at link:
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