How can we apply the methodology of NEC (NFPA 70) while the market products mostly IEC standard?

The IEC standard is a guide basically developed for the manufacturing, testing, regulating, and specifying of electrical and electronic products (equipment, devices, accessories, etc.) while the NEC or otherwise known as NFPA 70 is a guide or standard which concerns on how we can have a not only a functioning but most importanly a safe installation of any electrical equipment or electrical wiring.