OG10关于语法第8题

刚才看了OG10关于语法的讲解,第8题还是有点不太明白,请nn们点拨下.

Lacking information about energy use, people tend to overestimate the amount of energy used by
equipment. such as lights, that are visible and must be turned on and off and underestimate that used by
unobtrusive equipment, such as water heaters.

正确答案是visible equipment, such as lights, that must be turned on and off and underestimate that

标成红色的that怎么理解呢?是定语从句引导词么,可前面有逗号,为什么能用that呢?

visible equipment(, such as lights, )
        that must be turned on and off and underestimate that

插入语