manhole sizing software?

[anbm]

Are there formulas, online software to calculate and specify manhole size based on the quantity of conduits go through it? Thank you.

 

[JoeStillman]

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.

 

[anbm]

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.

Please explain again about 12x cable diameter rule, where does that come from?

 

[zbang]

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.

AFAIK all MV cable companies publish the bending radii for their products.

 

[JoeStillman]

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.