240.4 (g)

[Rich Elec.]

Could someone please decipher how 240.4 (G) allows conductors for motors, A/C units and other items to be sized at their 75c amperage.

I am reviewing the material and I need a little direction.
The section does not specifically spell this all out.

Thanks

Rich.

 

[raider1]

240.4(G) permits overcurrent for specific conductor applications to be provided as referenced in Table 240.4(G).

So you look at the Table and see the overcurrent protection for motors needs to conform to Article 430, Parts III, IV, V, VI, VII.

Chris

 

[Rich Elec.]

I was thinking faster than I was typing.
I meant to ask how the table allows #12 cu to be sized under the 75C column.
How does 430.22 allow this?
240.4 (D) states: Unless specifically permitted in 240.4(E) or 240.4 (G)...

The question I have is, where is this specifically permitted?

Thanks

 

[infinity]

In 310.16, #12 THHN with 75 degree connections is rated for 25 amps. Using it for circuits that don't fall under 240.4(G) means that you must use the ampacities in 240.4(D). That means that your stuck with limiting #12 THHN to 20 amps even though the conductor is rated for 25 amps in 310.16.