Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
My journeyman’s calculation prep book has to be wrong again
The question is:
What is the minimum width of a ventilated trough cable tray needed for three 250 kcmil THWN, single copper conductors, six 500 kcmil THWN copper single conductors and three 750 kcmil XHHW compact ALUMINUM single conductors. All conductors have 600 volt insulation.
Book answer is 9 inch cable tray with book calculations showing 8.2341” inches squared needed. Table 392.22 B 1 Column 1 shows an 8” tray width to provide 8.5” squared area which is sufficient for 8.2341” squared area needed for these cables. Why does the book select an over size tray than the minimum width cable tray?
The question is:
What is the minimum width of a ventilated trough cable tray needed for three 250 kcmil THWN, single copper conductors, six 500 kcmil THWN copper single conductors and three 750 kcmil XHHW compact ALUMINUM single conductors. All conductors have 600 volt insulation.
Book answer is 9 inch cable tray with book calculations showing 8.2341” inches squared needed. Table 392.22 B 1 Column 1 shows an 8” tray width to provide 8.5” squared area which is sufficient for 8.2341” squared area needed for these cables. Why does the book select an over size tray than the minimum width cable tray?
