RHH, THW similar Thermoset conductors (synthetic rubber). One of the listing (the second in each table) has an asterisk and the asterisk refers to conductors without an outer covering.
NEC Art 100 has a definition of "Conductor, covered" and the NEC handbook elaborates on this very "slightly". It is uncertain whether this definition of "covered" refers to the Annex C use of "covering"
Table 310.13 shows that these conductors and USE, USE-2 may or may not have an outer "covering" that is moisture resistant and sometimes even flame retardant. This use of "covering" does not agree well with the Handbook examples of "covered" cables in Art 100.
The UL White Book does not add much information to this issue of "coverings" on the thermoset cables.
My experience with single-conductor cables of these types in 14-4/0 AWG is that none of these cables have an outer covering and while some may have two layers of insulation, the outer diameter is the same as those with a single layer on insulation.
It would appear that I should be using the second conduit fill tables with the asterisk which allows more conductors per conduit size than the first table in each series.
Agree? And then why is the more common usage table not listed first? Hangover from the 1920's when all cables had outer coverings? Any old guys out there that know?
NEC Art 100 has a definition of "Conductor, covered" and the NEC handbook elaborates on this very "slightly". It is uncertain whether this definition of "covered" refers to the Annex C use of "covering"
Table 310.13 shows that these conductors and USE, USE-2 may or may not have an outer "covering" that is moisture resistant and sometimes even flame retardant. This use of "covering" does not agree well with the Handbook examples of "covered" cables in Art 100.
The UL White Book does not add much information to this issue of "coverings" on the thermoset cables.
My experience with single-conductor cables of these types in 14-4/0 AWG is that none of these cables have an outer covering and while some may have two layers of insulation, the outer diameter is the same as those with a single layer on insulation.
It would appear that I should be using the second conduit fill tables with the asterisk which allows more conductors per conduit size than the first table in each series.
Agree? And then why is the more common usage table not listed first? Hangover from the 1920's when all cables had outer coverings? Any old guys out there that know?
