Residential Load Calculations Spreadsheet – Part Three



In the Two previous topic;

Residential Load Calculations Spreadsheet – Part one,and

Residential Load Calculations Spreadsheet – Part Two

 I explained the steps # 1, 2 &3 and today, I will continue explaining the final steps 4 & 5 as follows:



Step 4: Article 220.54 (Electric clothes dryers – dwelling units) see fig.1



fig (1): Step 4


The load for household electric clothes dryers in dwelling unit(s) shall be 5000 watts (volt-amperes) or the name plate rating, whichever is larger of each dryer served.

1- Enter the watt load of the electric clothes dryer (For the standard method any value less than 5000 watts will be defaulted in the dryer demand load)
Note: don’t enter the volt-amperes of more than 4 household electrical dryers.

2- Output: the dryer demand load in VA.
                                                                                                                        


Step 5: Article 220.55 (household electric ranges - dwelling units) 
see fig.2


fig (2): Step 5




First :Standard mode
Demand loads for household electric ranges, wall mounted ovens, counter mounted cooking units, and other household cooking appliances over 1 ¾ KW rating.
We have two load calculation methods:


load calculation method #1:

insert one Electric range KW or
insert the total number of electric ranges and other cooking appliances not over 12 KW each
you will get the max demand load of method #1


load calculation method #2:

it shall be permissible to add the nameplate ratings of all cooking appliances rated 3 ½ KW but not more than 8 ¾ KW and multiply by the demand factors found in table 220.55
you will get the cooktop & oven demand load of method #2


the calculator will select the smaller max demand load of the two methods.


Second : Optional mode :

When using a gas range, be sure to use the check to box in the right or the calculation will not total because it appears incomplete because load calculation method #2 does not apply to a optional mode.




the total residential demand load sum (see fig.3)



fig (3)


Load
Get it from
general lighting demand load
Step #1
greater of heat @ 100% VS A/C @ 100%
Step #2
appliance demand load
Step #3
dryer demand load
Step #4
range demand load
Step #5
service demand in VA
Total sum of demand loads for steps from #1 to #5

demand load in A
The service demand load divided by 240 V (3-Wire, single phase service or feeder)

neutral demand in A
Based on NEC 220.61
Min service requirements in A
The nearest higher value to the value obtained as demand load in A

Min. feeder size: if an optional calculation this cell is “0”, you have not entered a nameplate rating in step 5 for cooking appliance(s) or if there is a gas range check the box in step5

Calculated from NEC 220.40 for standard mode and for optional calculations mode it will be calculated from article 220.80
Min neutral size
Based on NEC 220.61

The neutral calculations is always based on ART 220.42 thru 220.61 and not affected by the use of the “optional calculation”.

Eq. grounding conductor: the 250.24(C) permits the grounded circuit conductor to be sized not less than the maximum unbalanced load

Selected based on NEC 250.24
Check box for aluminum conductors

If you plan to use Aluminum conductors, just check the box




now, we finished explaining this wonderful spreadsheet and I hope that all of you can use it easily by using this manual .if any one of you need to ask for more clarifications about any step in this spreadsheet , just write you questions in comments  and i will reply immediately.

finally, don't forget to down load a copy from  Residential Load Calculations Spreadsheet, by pressing on the link then choose save as.


Post a Comment

Leave a comment to help all for better understanding