Fiber Optic Box Sizing : E Light Safety, Training and Leadership Blog
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(303) 754-0001

Fiber Optic Box Sizing

by Ted Smith on 10/18/17

In construction and solar field we install a large amount of fiber optic cables. When sizing pull or junction boxes for Fiber Optics we need to keep in mind that they same rules that apply to electrical conductors, apply to fiber optic cables. This means that a pull box for example would need to comply with the rules of 314.28. For example, If it is a straight pull, then it must be at least 8 times in length as the largest raceway entering the box .

This is because article 770 is in Chapter 7 of the NEC. According to Article 90.5 the NEC is divided like this:
Chapters 1-4 are the National Electrical Code and the items there apply to all installations.
Chapters 5-7 amend and modify chapters 1-4. They add rules or make special rules for special installations, but unless specifically amended, the rules of Chapters 1-4 apply.
Chapter 8 Communications is a stand alone code and nothing in Chapters 1-4 applys to the items in Chapter 8, unless Chapter specifically references a requirement in Chapters 1-4
Chapter 9 Contains Tables that are referenced by 2 or more Articles.


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