New York State Master Electrician Practice Exam

What is the minimum insulation temperature rating required for branch circuit conductors within 3 inches of a ballast?

1. 75C degrees

2. 90C degrees

3. 100C degrees

4. 125C degrees

The correct answer is: 90C degrees

The minimum insulation temperature rating required for branch circuit conductors that are installed within 3 inches of a ballast is indeed 90°C. This requirement is put in place because ballasts can generate significant heat during operation, and conductors that are in close proximity to these heat sources need insulation that can withstand elevated temperatures to ensure safe operation and prevent insulation degradation. Selecting insulation rated for 90°C provides a sufficient margin of safety in these scenarios, as it allows the conductors to handle the thermal effects created by the ballast without risk of melting or damage to the insulation. This is critical for maintaining electrical safety and system reliability in both residential and commercial applications. Other options, while they represent insulation ratings that may be suitable for different applications, do not meet the specific requirement for proximity to a heat-generating appliance such as a ballast. Therefore, 90°C is the proper choice for this context, aligning with the standards established in the National Electrical Code (NEC).