Ampacities calculation of cables in ducts

[Champion]

Could any online expert tell me some docs about Ampacities calculation of cables in ducts? Thanks.

 

[dpc]

Do a web search on "Neher-McGrath". They wrote the seminal paper on this subject back in early 1960s or maybe earlier. It is the basis for the cable ampacities in the NEC and for several computer programs.

Hope that helps.

 

[redtrumpet]

The Neher-McGrath paper is included with the IEEE Power Cable Ampacity Tables.

Also try "Rating of Electric Power Cables", G. J. Anders, IEEE Press.

 

[jbartos]

Suggestion: Visit

http://www.nema.org

and ask them for a copy of the standard (small fees apply). Please notice that the cable duct is not defined in the current IEEE Std 100-2000 "Dictionary". The cable tray is.
and

http://www.ieee.org

http://standards.ieee.org/reading/ieee/SB/Jan95/bear-scc31.html

http://standards.ieee.org/cgi-bin/status?835

etc. (also small fees apply)

 

[cuky2000]

The Neher-McGrath article is excellent but not recommended for beginners. For low voltage and MV application the NEC, IEEE and engineering guide published by cable manufacturer such as Okonite are perhaps more practical if the configuration of your duct bank is listed in those references.

For high voltage, none standard configuration, very dept, unusual temperature or mixture of different type of voltage and cable size, the use of computer program could be very helpful.

The following thread could help with this question:

thread238-9203
thread238-22126
thread242-10154

 

[Champion]

Thanks you all. It's really help me a lot.