ECN Forum Forums Technical Discussion Electrical Theory and Applications Cable Ampacities

Question regarding ampacities for cable. 1999 NEC Table 310-16 basically reflects ampacities of current carrying conductors in raceways, CABLE, etc. Then there Table 400-5 discussing ampacities of cords and CABLE.

Q1: For a #8 AWG conductor, there are differences in ampacities between the two Tables. With no regard to ambient temperature etc. T. 400-5 lists certain types (SJO, STO etc.), while 310-16 lists conductor insulation types (RHW, THW etc.) Given this circumstance, are there two types of "CABLE" available that fall each respectable NEC table?

(I do know there is the new 2002 code but for our writings we only current copyright for 99 code)

Any assistance in this matter would be greatly appreciated.

AF Electrician
Course Developer

See Section 240-3. Protection of Conductors
Conductors, other than flexible cords and fixture wires, shall be protected against overcurrent in accordance with their ampacities as specified in Section 310-15, unless otherwise permitted or required in (a) through (g).

Yes, there are two types of cables.

First are the flexible cord style (i.e. extension cords) these are protected according to NEC99 400-5.
Second are all of the other styles (i.e. NM, and AC) which are protected according to NEC99 310-15.

Now that clears things up and makes sense! Thanks!