national electrical code

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faranca77

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Why the national electrical code for dwelling units don't apply the continuous and non continuous load to calculate the over load protection device and cable selection calculation, correction factors for temperature



The national electrical code discuses about the motor-compressor, motor-compressor largest load, protective device, and no discussion about air handling units, chillers



the national electrical code discuses the method of calculating the demand load one panel board the question if I have panel (A) and (B), (C), (D), each of them contain lighting , motors and sockets loads and appliances and air conditions how I cane calculate the demand load for the main panel MDB-1 that feed all this panel boards and the main feeder, main circuit breaker and calculate the demand load of panel board MDB that feed the (MDB-1), (MDB-2), (MDB-3), (MDB-4) ,main feeder, main circuit breaker where (MDB-2), (MDB-3), (MDB-4) same as MDB-1 but different in loads not typical and, also calculation transformer load.



The national electrical code discuses the demand loads of central space heating only for optional method for dwelling units what about the general method for dwelling units and the non-dwelling units.
 
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Smart $

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Location
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faranca77 said:
Why the national electrical code for dwelling units don't apply the continuous and non continuous load to calculate the over load protection device and cable selection calculation, correction factors for temperature
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It does, as far as I can tell. Perhaps I missed something somewhere... Would you please elaborate the specifics of why you say the NEC don't apply such to dwelling units?


The national electrical code discuses about the motor-compressor, motor-compressor largest load, protective device, and no discussion about air handling units, chillers
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The motors for air handlers and chillers are covered under Motors... [Refrigerant] motor-compressors are distinctly different type of motor application in that the motor and compressor are hermetically sealed within one housing.

the national electrical code discuses the method of calculating the demand load one panel board the question if I have panel (A) and (B), (C), (D), each of them contain lighting , motors and sockets loads and appliances and air conditions how I cane calculate the demand load for the main panel MDB-1 that feed all this panel boards and the main feeder, main circuit breaker and calculate the demand load of panel board MDB that feed the (MDB-1), (MDB-2), (MDB-3), (MDB-4) ,main feeder, main circuit breaker where (MDB-2), (MDB-3), (MDB-4) same as MDB-1 but different in loads not typical and, also calculation transformer load.
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You use the same and all connected loads to calculate the main panelboard or switchgear and service conductors, and using the same calculation method... i.e. as required in Article 220, Section III, IV, or V. Also remember, you are calculating minimum ampacity ratings. There is no stipulation preventing one from upsizing for future possibilities.


The national electrical code discuses the demand loads of central space heating only for optional method for dwelling units what about the general method for dwelling units and the non-dwelling units.
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It goes without saying that the general method and the optional method are different. I don't know the specific reasons why, and try not to supply conjecture as concrete answers. Perhaps someone in the know will chime in...
 
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faranca77

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thank u for caring to replay my answers

thank u for caring to replay my answers

thank u for caring to replay my answers the explanation of my first qestion is


after I obtain the total demand of dwelling with kVA ,calculation of current, the national electrical code take this current directly and select the suitable cable without applying correction factor for ambient temperature and correction factor for number of conductors in raceway and all other correction factors applied in case of non dwelling units why ????????????

the follwing questions
If I have chiller with 8 compressors plus 4 fans each compressor have power 25 kva
How can calculate
a-chiller circuit breaker
b-chiller disconnected switch
c-chiller cable

If I have the air condition mini split unit the out door unit contain compressor and fan and indoor unit contain fan only
The main power supply cable come from panel board to out door unit and outdoor uint fed indoor unit with small cable
How I can calculate
a- Air condition split unit circuit breaker
b- Air condition split unit disconnected switch
c- Air condition split unit cable size for outdoor unit
d- Cable size for indoor fan


If I have the air condition central split unit the out door unit contain 4compressor and 2fan and indoor unit contain fan only
The main power supply cable come from panel board to out door unit and outdoor unit fed indoor unit with small cable
How I can calculate
a- Air condition central split unit circuit breaker
b- Air condition central split unit disconnected switch
c- Air condition central split unit cable size for outdoor unit
d- Cable size for indoor fan

I am sending jpg and PDF format and my all questions have color >>>>red<<<< I prepare this file to do not lost your time
http://rapidshare.com/files/136634612/EXPLANATION_Model__1_.pdf.html
 
Smart $

Smart $

Esteemed Member
Location
Ohio
faranca77 said:
thank u for caring to replay my answers the explanation of my first qestion is


after I obtain the total demand of dwelling with kVA ,calculation of current, the national electrical code take this current directly and select the suitable cable without applying correction factor for ambient temperature and correction factor for number of conductors in raceway and all other correction factors applied in case of non dwelling units why ????????????

...
Click to expand...
It takes a good portion of the NEC to put compliance requirements into words. The words it takes to explain these requirements can easily reach a hundredfold. So... This would go a lot easier if you break down the scope of your intent to one issue at a time.

For starters, let's deal with the issue I quoted above from your second post...

I understand WHAT you attempting to point out, but I am not aware that the code actually does what you are claiming it does. As it stands now, I can only say your interpretation is incorrect according to my general and literal comprehension of the code. Please cite specific article(s) and subsections by number, such as 110.14(C)(2). Until you do, we have no grounds to discuss anything. All that will result is conjecture. We may even go back and forth saying I'm interpretting code correctly and you are not... and vice versa. Maybe I missed something, maybe you missed something... I simply do not know until you elaborate... and the lack of responses indicate others are likely of the same persuasion :rolleyes:

So what article and subsection does it say to apply adjustment factors to cable ampacity for non-dwelling units? If the code says not to apply adjustment factors for dwelling units somewher else, then what article and subsection?
 
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faranca77

Member
demand

demand

the national electrical code discuses the method of calculating the demand
load one panel board the question if I have panel (A1) and (B1), (C1), (D1),
each of them contain lighting , motors and sockets loads and appliances and
air conditions

A-how I cane calculate the demand load for the main panel
MDB-1 that feed all this panel boards and the main feeder, main circuit
breaker

B-and calculate the demand load of panel board MDB that feed the
(MDB-1), (MDB-2), (MDB-3), (MDB-4) , (HVAC +plump ), loads main feeder, main circuit breaker where
(MDB-2), (MDB-3), (MDB-4) same as MDB-1 but different in loads not typical related panels for (MDB-2) A2,B2,C2,D2 AND so on but A1 not equal A1 and so on.



C-also calculation transformer load demand



I have suggestion for solution of A,b,c but I want to take ur opinion that I can







Step#1 Calculate the connected load of panel MDB-1 is just the sum of all (lighting, sockets, motors ...) FOR panel boards A1, B1, C1, D1 without applying the demand (220.42,220.44,430.24, other demand factors.)

Step#2 To calculate the demand load of panel MDB-1 is the sum of connected load for all loads (lighting, sockets, motors,......)for panel boards A1,B1,C1,D1 with applying the demand(220.42,220.44,430.24 for largest motor in (A1,B1,C1,D1,), other demand factors)

Step#3 to calculate the cable size for MDB-1 panel (apply 220.19) to MDB-1 demand Step#2

Step#4 to calculate OCPD for MDB-1 panel (apply 215.3) to MDB-1 demand Step#2

Apply the same above for (MDB-2), (MDB-3), (MDB-4)



Step#5 Calculate the connected load of panel MDB is just the sum of all (lighting, sockets, motors ...) FOR panel boards (MDB-1), (MDB-2), (MDB-3), (MDB-4), other (HVAC +plump) without applying the demand (220.42, 220.44, 430.24, other demand factors)

Step#6 To calculate the demand load of panel MDB is the sum of connected load for all loads (lighting, sockets, motors,......)for panel boards (MDB-1), (MDB-2), (MDB-3), (MDB-4), (HVAC +plump ) other HVAC with applying the demand(220.42,220.44,430.24 {for largest motor x 1.25 +all motors, fans and water, fire pumps for (HVAC +Plump ),other demand factors)

Step#7to calculate the cable size for MDB panel (apply 220.19) to MDB demand step Step#6



Step#8to calculate OCPD for MDB panel (apply 215.3) to MDB demand step Step#6







Step#9Calculation the transformer circuit breaker and cable according to transformer KVA not total demand KVA of MDB where MDB main panel taking from transformer
 
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haskindm

Senior Member
Location
Maryland
Your questions are far to complex and convoluted to address on a forum such as this. It appears that you need to take courses or at least spend many hours studying the application of the NEC. Perhaps you need to work with an electrician and or engineer for awhile to get some practcal experience. I have taught code for twenty years and it would take many pages of text to address your questions.
 
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faranca77

Member
My questions not difficult

My questions not difficult

My questions not difficult and this is the actually single line diagram for any building and there is some of nec memberships answer me
I hope u replay me with good method thank u very much
 
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