?
Monday, June 19, 2023
Question:
Hello Code Question of the Day, I am Paul Chahine a mechanical engineer currently working in Quebec Canada. I am trying to calculate the ampacity of cables passing together for multiple compressors. I am using many flexible cords/cables SOOW type. I see that they are not allowed to be in raceways in (400.12). I also see in Table 400.5(A)(3) the adjustment factor for More Than Three Current-Carrying Conductors in a Flexible Cord or Flexible Cable.
My questions are:
1) What if I have many SOOW cables passing together? Should I add the sum of conductors in all the cables and use the factor in Table 400.5(A)(3)? For example, if I have 5-SOOW each with 3 current carrying conductors, do I calculate the ampacity as follows: 5x3=15 in total conductors and use 15 in Table 400.5(A)(3) so my ampacity factor is 50%?
2) Can we pass them and use tie wraps to fix them on the body of the machine? If not, can you specify the installation paragraph from the NEC that best describes my situation to be able to correctly install them?
Thank you so much. Waiting for your reply.
Have a great day!
A
Answer:
Hi Paul and thank you for participating in the CQD all the way from Quebec.
Regarding question 1) - Section 400.12(1) The information provided in question 1, implies that the cords will be bundled at some point of the installation, suggesting that the cord is going to be installed in some type of cable tray or other support means to accommodate multiple cords bundled together. Section/Table 400.5 does not specifically address ampacity adjustments when bundling flexible cords/cables. This is likely because Section 400.12(1) prohibits the use of flexible cords or cables like SOOW, as a substitute for fixed wiring of a structure and Section 400.12(4) prohibits flexible cords/cables from being attached to the building surfaces and to bundle flexible cord/cable would more than likely violate either one or both Sections.
Regarding question 2) – Section 400.12(4) prohibits flexible cord/cable from being attached to the building surface. However, there is an exception provided to 400.12(4) allowing a flexible cord/cable to be attached to the building surface in accordance with Section 368.56(B) which applies to the wiring from a busway/bus switch to specific equipment and conforms to the four (4) conditions listed in Section 368.56(B)(1)-(4).