When is it permissible to not use a box for splices on construction sites?

The answer is centered around the specific conditions under which it is permissible to omit a box for splices on construction sites. When all conductors are nonmetallic and grounding is maintained, it is acceptable to not use a splice box since nonmetallic conductors, such as NM (nonmetallic sheathed cable), typically do not require a junction box. This is particularly relevant in scenarios where the conductors are designed to be installed without additional protection and where grounding ensures safety and compliance with electrical codes.

Maintaining grounding is crucial because it helps prevent electrical hazards, ensuring that any fault current can be safely conducted to the ground, reducing the risk of electrical shock or fire. Therefore, when the installation involves only nonmetallic conductors that adhere to grounding requirements, the necessity for additional splice boxes is mitigated.

In contrast, other situations mentioned, like using metal wiring or overhead installations, often still require splice boxes because of the risks inherent in those configurations. Additionally, temporary installations may also require careful consideration and often still adhere to splice box regulations to prevent hazards, which limits their permissibility based solely on the type of installation.