Devices built according to the? standard have four times longer life expectancy.

Answer: NEMA (National Electric Manufacturers Association)

Explanation:

NEMA (National Electric Manufacturers Association) is defined as the association in the field of electrical equipment that certifies the manufactured electrical tool and equipment.

It has type four certification which gives assurance about the protection of equipment use and existence in indoor as well as outdoor area without getting damaged and degraded. It has the tendency to repel dirt, corrosion, blowing wind, rain etc.

Therefore, the devices that are built with the standards of NEMA have higher expectancy of life as compared to other equipment and tools.