States terms to be rated at 90c unless otherwise idenitfied.
Question is Wire rated at 90c for terms 105 for derating."
No. There are cables that have 105 temp ratings. If your terminal is not rated at 90
or 105 C degrees then you have to reduce the cable rating. Problem there are no tables in the NEC to get that figure. Contact the cable MFG for assistance.
"The way it reads I'd say is if you use MV105 the amps are rated at 180.
Question Do all other factors come into play as for Parallel conductors".
You are correct. MV105 is rated at 180 amps
provided you conform to the information given
by Table 310.77. 3 conductors per duct,
Temp 20C, 100% LF, Earth Rho factor 90 and
conductor max temp either 90 or 105C.
Note that you must use Fig 310.60 for the duct bank arrangments.
Under Table 310.77, the first table is for
1 circuit, 3 cables, Detail 1 Fig 310.60.
The second table under 310.77 is for 3 circuits, detail 2 and so on thru the rest of the tables.
You would not have parallel cables in the ducts so no derating would be needed.
Are you installing 5 kv cable?
[This message has been edited by Bob (edited 11-12-2004).]