408.55 exception #4 (05 NEC)

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mayjong

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i had this one on a test-
if no conductors are terminated in the panel , bending is sized with 312.6 (A)
BUT- i can't size both with that table therefor i have to use 312.6(B) for either the top or the bottom sizing.
my question is-
how do i know which table to use for the top, and which to use for the bottom???

for instance the question was like this
-how many inches minimum top and bottom bending space is required for 500 kcmil conductors entering/leaving the top of a 400A panel with no conductors terminated in it?

thanks!
 
mayjong said:
-how many inches minimum top and bottom bending space is required for 500 kcmil conductors entering/leaving the top of a 400A panel with no conductors terminated in it?
Click to expand...

This sounds like more of a 314.28 type of question. Did the test question give a conduit size?
 
the question was about a panel-
here it is exactly-
"two 500kcmil conductors per terminal enter or leave the top of a 400A panelboard opposite their terminals.No conductors terminate in the bottom of the enclosure. the panelboard shall have a minimum top and bottom wire bending space of:
a. 14" of wire bending space at the top and bottom
b. 8" of wire bending space at top and bottom
c. 8" of wire bending space at top and 14" of wire bending space at bottom
d. 14" of wire bending space at top and 8" of wire bending space at bottom.


so 480.55 ex 4 says i use 312.6(A ) for top or bootom, but not both.
how do i know (where does it say) which one to use for the top, and which one to use for the bottom???
am i over thinking this?
thanks!
ps- i have the answer , just not the reason WHY it's the answer.
 
What I have done, is to label each table appropriately with the different wording.

(B)(1) is for Table 312.6(A)

(B)(2) is for Table 312.6(B)


I write on the space available above the table the wording of the titles of the two subsections.
 
oh, i see
because it says " no conductors terminate in the bottom of the enclosure."
then the assumption is some DO teminate in the top . therefore it would require d. 14" of wire bending space at top and 8" of wire bending space at bottom.
good guess kb!
 
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