The Utility Interconnection 120 Rule
and NABCEP Test Taking Tips with Richard Stovall
The articles mentioned in the lecture last night (Home Power Magazine) articles:
Last minute test prep on conduit sizing:
12, #10 THWN-2 conductors are to be installed in RMC. The temperature is 50ºC.
What size conduit is needed?
Answer: 1”. Refer to Annex C, Table 8. Be careful not to use Table 8 (A) for ‘compact conductors’
Tricky- temperature is given here, but it is not needed. This would affect ampacity, but to determine the conduit needed this is extraneous information that can throw you off.
Notice in the beginning of Chapter 9 (page 711 in 2011 NEC™):
“Notes to tables:
(1)See informative annex C for the maximum number of conductors and fixture wires, all the same size permitted in trade size.”
If you were trying to discern conduit size required for conductors of various sizes in conduit together, you would have to use Chapter 9 Table 5 for the conductor area (in square inches) to determine conduit area required. Table 4 would be used to determine conduit required for these conductors.
Again, see in the beginning of Chapter 9 (page 711 in 2011 NEC™):
(6) For combinations of conductors of different sizes, use table 5 and table 5A for dimensions of conductors and Table 4 for the applicable conduit or tubing dimensions.
An example on applying these table to size conduit when you have multiple wire sizes will be posted within the next few hours in the SolPowerPeople Forum.
GOOD LUCK ON THE EXAM!!!