Codes & Standards
Conductors and cables in conduits and tubing – Code File, December 2022
December 6, 2022 By Nansy Hanna, P.Eng.
December 6, 2022 – The Canadian Electrical Code’s Tables 6 and 9 have seen some modifications over the last few code cycles. Historically, Table 6 served as a quick reference for determining the number of conductors of the same size in conduit. Now, based on changes to Tables 6 and 9 in the CE Code (2021 ed.), a calculation or comparison may provide a better understanding of the changes.
Our technical team prepared the analysis at right to help us see where we were, and where we are now with the current 2021 edition.
By way of comparison, have a look at the impact on conduit fill using Table 6 over the last few code cycles:
How many No. 10 AWG RW90 unjacketed 600V conductors will fit in a 16-mm (1/2-in.) EMT conduit?
• 5 conductors (2012 code)
• 2 conductors (2015 & 2018 eds.)
• 4 conductors (2021 code)
Here is a process for determining the maximum number of same-size conductors in conduit using Tables 6, 8 and 9:
1. Use Table 8 to determine max percentage conduit fill.
2. Select correct Table 9 based on Table 8 results.
3. Use Tables 9A-9H to find type of conduit and size to be used; record cross-sectional area value.
4. Go to appropriate Table 6 based on type of conductor used.
5. Tables 6A-6K are used to select conductor size. Follow the chart to the right until the area of conductors is less than or equal to the value recorded from Table 9. From this value, the corresponding number of conductors will be at the top of the Table.
6. This value at the top of the chosen Table 6 is the maximum number of same-size conductors permitted in the conduit.
This process can also be performed in reverse to determine minimum conduit size when the number of same-size conductors is known. For example:
What is the minimum size EMT conduit in which three (3) No. 10 AWG RW90XLPE 600V unjacketed conductors will fit?
1. Choose Table 6A for RW90XLPE 600V unjacketed conductors
2. Find the area of (3) No. 10 AWG conductors (47.08 mm2).
3. Table 8 for max percentage conduit fill, and see which Table 9 to select.
4. Table 8: three (3) conductors = 40%. Go to appropriate Table 9 at 40% fill (Table 9G).
5. Table 9G: Choose correct conduit type (EMT).
6. Table 9G: Compare results from Table 6A (47.08 mm2) to cross-sectional areas for different EMT sizes (47.08 mm2 < 72.51 mm2 = 16 mm [1/2-in.] EMT).
So 3(*) x No. 10 AWG RW90XLPE 600V unjacketed will fit in a minimum 1/2-in. EMT conduit. (Based on the above calculation, maximum 4x No. 10 AWG RW90XLPE 600V unjacketed conductors could fit in 1/2-in. EMT conduit, if needed.)
Nansy Hanna, P.Eng., is senior director, Engineering & Regulations, at Ontario’s Electrical Safety Authority (ESA). She is also chair of the Canadian Advisory Council on Electrical Safety (CACES) and a member of the ULC Advisory Council and CSA Technical Committee on CE Code-Part I. She can be reached at firstname.lastname@example.org.
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