I have a question for the experienced electricians in the group. I need to run a #4-3 type SER cable through an underground conduit. I can find tables in the NEC that cover conduit fill limits for single conductors, but not for cabled conductors. Is the cable considered a single wire for this purpose or 4 wires? Thanks
Per note 9 NEC 2002 Chpt 9 Tables, multiconductor cables are to treated as single conductor cable. Do get the correct cross section area from manufacturer specs.
The cross section is the diameter, based on the widest dimension. If it gets twisted that will be the swept area when you pull it in.
There is a table in the back of the book for cross sectional area. Find out what it is for one wire, multiply by 4, then check the other table for 40% fill area.
snipped-for-privacy@nospamcox.net (newsreader) wrote in :
I thought that was correct, just wanted a second opinion. Per Mfr. diameter is .77" so I can use 3" conduit to meet 40% fill maximum. Thanks to all who responded.
Well .77 is way too high for #4 wire.
You are looking for area in SQ INCHES from table 5A sect 70-887 if it is aluminum. For copper it is in table 5 sect 70-884.
Copper = .0824 Aluminum = .0881
.0881 X 4 conductors = .3524
According to table 4, sect 70-882, you can use an 1-1/4" Conduit.
AEC Electric & Controls Michael R snipped-for-privacy@sbcglobalremovethiscrap.net
I think cross section is by area, not diameter. Therfore: ((.77^2)/(.4))^1/2 = 1.217. So, 1-1/4 inch conduit should be OK.
I chuckle every time I hear the question....How many #12s can you put in a half inch pipe. Someone asks.......What's the record?
I know you wanted a serious answer. Sorry I don't have one. :)
Depends on how many bends and LB's. I think I may have set a few records...
MLR
With, or without insulation? ;-)
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