Residential Load Calculations Spreadsheet – Part one

[ali hassan]

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”
The neutral calculations is always based on ART 220.42 thru 220.55 and
not affected by the use of the “optional calculation”.

1- User Info. Worksheet:

1- Enter the required information in the User Info. Worksheet As
follows:
Company name
Address
City, state, Zip code
Telephone &fax
Serial number

2- 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)

Input data:

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.

Output data:
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)

Input data:
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.

Output data:
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
Residential Load Calculations Spreadsheet – Part one

http://alihassanelashmawy.blogspot.com/2012/01/residential-load-calculations.html