manhole sizing software?

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anbm

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TX
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Designer
Are there formulas, online software to calculate and specify manhole size based on the quantity of conduits go through it? Thank you.
 
See NEC Article 110, Part V, starting at 110.70 for rules about manholes. Typically, the working space requirements require a bigger box than the pull box requirements of 314.28. And be careful of the minimum bend radius for cables over 1000V. 12x cable diameter can give you a larger space requirement than 8x conduit diameter.
 
JoeStillman said:
See NEC Article 110, Part V, starting at 110.70 for rules about manholes. Typically, the working space requirements require a bigger box than the pull box requirements of 314.28. And be careful of the minimum bend radius for cables over 1000V. 12x cable diameter can give you a larger space requirement than 8x conduit diameter.
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Please explain again about 12x cable diameter rule, where does that come from?
 
in Art 300, Part II. "Requirements for over 1000 Volts, Nominal"
300.34 Conductor Bending Radius. The conductor shall not be bent to a radius less than 8 times the overall diameter for nonshielded conductors or 12 times the overall diameter for shielded or lead-covered conductors during or after installation.
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AFAIK all MV cable companies publish the bending radii for their products.
 
300.34 Conductor Bending Radius. The conductor shall not
be bent to a radius less than 8 times the overall diameter for
nonshielded conductors or 12 times the overall diameter for
shielded or lead-covered conductors during or after installa-
tion. For multiconductor or multiplexed single-conductor cables
having individually shielded conductors, the minimum bend-
ing radius is 12 times the diameter of the individually shielded
conductors or 7 times the overall diameter, whichever is greater.
 
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