Code Question Of The Day

Charlie,

Thanks for the great NEC question service. I have a 460-volt, 3-phase motor rated 50 HP and the nameplate current is 58.5 amperes. The motor will run continuously in an exhaust fan application. I have installed three No. 6 THWN conductors in a 1-inch conduit for this motor. The HVAC installer indicated that on the last job, the electrician installed No. 4 AWG THWN to feed this motor. Table 310.15(B)(16) indicates that No. 6 THWN conductors are good for 65 amperes. Which is the minimum correct size conductor for this motor? Thanks in advance.

Sam Jenkins

Charlie,

I am a big fan of the Code Question of the Day. I truly appreciate the way you manage all of these good questions and the silly ones too! Here’s my question. My inspector has red-tagged my residential project saying that the insulation in the attic cannot be in contact with the recessed fixtures I’ve installed. He indicated there must be at least 3 inches of clearance all around and no insulation installed above the fixture. The fixtures are listed and marked “IC” rated. Am I missing something or is this inspector requiring something above Code minimum. Thanks for your help.

Bill Maddox

Hi Bill,

Thanks for participating. Section 410.116(B) covers installations of recessed fixtures and clearly indicates that if the fixture is marked “Type IC” then thermal insulation can be in contact with the fixture. You may have to show the marking on the fixture and the section of the Code that specifically permits thermal insulation to be in contact where so identified. The inspector has the responsibility for interpretations and approvals of installations as provided in 90.4. Sometimes the electrical contractors and electricians have to help them get it right.