Service calc

[dec]

Where can I find the actual verbage in the NEC that says to add 25% of the largest motor load to the service calcs?

 

[charlie b]

Table 220.3 points you to 430.26, which in turn points you to 430.24. The answer lies therein.

 

[Chamuit]

Do you mean 430.24.1 or Annex D8?

 

[dec]

Service calc

I have read the articles you mention, but for the life of me.... I do not see anything mentioning the quantity 25%. There are numerous mentions of using 125% .

 

[iwire]

I have read the articles you mention, but for the life of me.... I do not see anything mentioning the quantity 25%. There are numerous mentions of using 125% .

That is what you are looking for.

 

[dec]

Service calc

I agree with you..... So why does it show using 25% in the article posted in the IAEI ?

 

[GoldDigger]

That is what you are looking for.

Adding on 25% to 100% is the same as taking 125% in the first place (for the math challenged).

 

[jumper]

I agree with you..... So why does it show using 25% in the article posted in the IAEI ?

Can you post a link to article? Someone could then probably clarify what is written in it for you.

 

[iwire]

It really depends on the wording.

Add 25% to the load or treat the load at 125%. IMO either results in the same.

 

[dec]

Service calc

http://iaeimagazine.org/magazine/20...calculations-in-the-national-electrical-code/

 

[jumper]

http://iaeimagazine.org/magazine/20...calculations-in-the-national-electrical-code/

They merely added the 25% for largest motor separately from the original largest motor load which is the HVAC.

HVAC was 6000VA and then they took 25% of 6000VA for 1500VA, bottom of chart. It is the same if you just did it in one step and multiplied HVAC 6000VA x 1.25 = 7500VA. Math comes out the same.