In summary, metal junction boxes are the best choice for tough jobs. However, they can be more expensive and complicated to install than plastic boxes. Make sure you choose the correct box for. An electrical junction box is an enclosed housing designed to protect the splices and terminations of electrical wires, preventing accidental contact and mitigating the risk of electrical fires. These boxes are mandatory wherever wires are joined, ensuring the integrity of the circuit connections. Whether you're an electrical contractor, project engineer, or procurement professional. Metal boxes are durable, fire-resistant, and good for grounding.