I have a 42 circuit 3 phase panel with a 100 amp main. All the circuit breaker feeding branch circuit are 20 amp.. This panel was installl over 40 years ago. It has three 2" conduit leaving the panel into the a concrete wall. The conduit are over 2' long. With 14 circuit per phase the total amps. is less then 50% because of the 100 amp main can I use table B.310.11.
Table B.310.11
- Thread starter blackjack
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I am afraid that I do not understand what you are asking. That table has to do with assigning an ampacity. But you are talking about an existing installation. What are you planning to do with this installation?
Also, please note that if you measure the load, and get a value of under 50% of the rating of the panel, that does not mean that the "load diversity," as used in that table, is 50%.
Welcome to the forum. But please help us understand your situation.
Also, please note that if you measure the load, and get a value of under 50% of the rating of the panel, that does not mean that the "load diversity," as used in that table, is 50%.
Welcome to the forum. But please help us understand your situation.
Thanks for your fast responce. I am asking because I am a little confuse by when table ain Annex B can be used. Can you clear this up for me.
The area where the panel are located is being remodel. There are only three conduit leaving the panel that can be used without major changes in the equipment room. Table B.130.11 allow to use a 70% Adjustment factor. Table 310.15(B)(2)(a) I have to use 50% adjustment factor.
The note in the hand book after table 310.15 States" The factor in the second column of Table 310(B)(2)(a)are based on no diversity, meaning that all conductor in the raceway of cable are loaded to their Maximum rated Load."
The note which isn't part of the code state that diversity mean that not all conductor are loaded to there maximum rate. It does't say that some of the circuit got to be turn off.
The area where the panel are located is being remodel. There are only three conduit leaving the panel that can be used without major changes in the equipment room. Table B.130.11 allow to use a 70% Adjustment factor. Table 310.15(B)(2)(a) I have to use 50% adjustment factor.
The note in the hand book after table 310.15 States" The factor in the second column of Table 310(B)(2)(a)are based on no diversity, meaning that all conductor in the raceway of cable are loaded to their Maximum rated Load."
The note which isn't part of the code state that diversity mean that not all conductor are loaded to there maximum rate. It does't say that some of the circuit got to be turn off.
dana1028
Senior Member
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- San Francisco Bay area
Load Diversity
Load Diversity
I too had a question about this. This term - load diversity - used to be in the NEC and was removed some time ago [I'm going by forum discussion information - I think Don made a comment on this some time ago]... is now back in the code.
I really do hope someone jumps in here and addresses any incorrect assumptions I may be making.
As I understand Annex B, Table B 310.11 - if your conductors are only 'loaded' to 50% of their value [thus are 'diversified'], then you can use the formula in this table to determine their [allowed] ampacity.
As I look at this table it appears to only address 'a load diversity of 50%' and no other values. So if you had some other value you could not then use this table via interpolation???
Load Diversity
I too had a question about this. This term - load diversity - used to be in the NEC and was removed some time ago [I'm going by forum discussion information - I think Don made a comment on this some time ago]... is now back in the code.
I really do hope someone jumps in here and addresses any incorrect assumptions I may be making.
As I understand Annex B, Table B 310.11 - if your conductors are only 'loaded' to 50% of their value [thus are 'diversified'], then you can use the formula in this table to determine their [allowed] ampacity.
As I look at this table it appears to only address 'a load diversity of 50%' and no other values. So if you had some other value you could not then use this table via interpolation???
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