NEC 2011 690.8(B)(2)(a)- conductor sizing

[GR Solar]

This code reference uses the term "conditions of use". Is the 125% continuous use factor which is used in 210.19(A)(1) and 215.2(A)(1) considered a "conditions of use" OR is this continuous use factor addressed in 690.8(B)(2)(a)? If the first is true than there will be situations when the 125% continuous use factor is applied alongside the other "conditions of use" factors such as temperature derates and conduit fill derates. If the later is true, than the 125% continuous will not be applied with the other "conditions of use" factors such as temperature derates and conduit fill.

John Wiles from the Institute for Energy and the Environment (IEE) would agree with the later. In his article "Conductor Sizing & Overcurrent Device Ratings" for Home Power Magazine states it this way:

Next is the 125% requirement in 210.19(A)(1) and 215.2(A)(1): "The minimum feeder-circuit conductor size, before the application of any adjustment or correction factor, shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load." The emphasized words indicate that there's no requirement to apply the 125% and the condition of use at the same time.

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I would appreciate any input on this subject. Thanks.

 

[copper chopper]

thats simple its there so that you wont put to much load on to small of wire, resulting in the wire burning out or damage to loads. There are certain ajustment factors for every unique installation. Thats my answer if its not what your looking for then try shortening your question to 1 sentence so we can understand what your looking 4.:ashamed:

 

[GR Solar]

NEC 2011 690.8(B)(2)(a)- conductor sizing- Shorter post

NEC 2011 690.8(B)(2)(a)- conductor sizing- Shorter post

Sorry for the confusion. Here is my question:

690.8(B)(2)(b) uses the term "conditions of use". Is the term "conditions of use" meant to include the 125% continuous use factor OR is this continuous use factor addressed in 690.8(B)(2)(a)?

 

[copper chopper]

sorry i took so long i had to get a 2011 code book to see this as i am in wisconsin and we have decided here not to adopt the 2011 nec. and these articles are not in the 2008 nec.

The way i read it is that they want you to calculate it A= is 125 percent of max amps without the conditions of use factors
B=is max amps with conditions of use applied
C= means the larger of A or B is what you use to determine overcurrent size.