What is the maximum voltage rating for NM-B?

The maximum voltage rating for NM-B (Non-Metallic Sheathed Cable) is set at 600 volts. This rating is standard for residential and light commercial electrical wiring in the United States, as defined by the National Electrical Code (NEC). NM-B cable is commonly used for interior wiring in various applications, such as residential buildings, because it is designed for use in dry locations and is easy to work with.

The 600-volt rating provides flexibility for many typical electrical systems where higher voltage requirements are not necessary. It's important for electricians and contractors to adhere to the specified voltage ratings to ensure safety and compliance with electrical codes, which are established to minimize the risk of fire or electrocution.

Other options present voltage ratings that are beyond the legal and safe operating range for NM-B cables. Therefore, the selection of 600 volts is appropriate and aligns with the standards set for this type of wiring.