Which sort of connectors can be used for connecting MC cables to the box mentioned in the circuit plan?

Using external connectors for connecting MC (Metal Clad) cables to a junction or outlet box is essential for adhering to electrical codes and ensuring a secure, reliable connection. External connectors are specifically designed to secure the cable's outer sheath, providing strain relief and protecting the conductors from damage. They also help maintain the integrity of the box's seal against dust and moisture, which is particularly important in environments where environmental factors can affect the electrical system's performance.

In contrast, internal connectors are typically used for connections that are made within the enclosure itself and do not provide the external strain relief or environmental protection necessary for MC cables. Universal connectors may not specifically address the requirements for MC cable installations, and heavy-duty connectors, while they could withstand higher loads or more demanding environments, are not explicitly tailored for standard MC cable applications. Using external connectors ensures compliance with safety standards and best practices within electrical installations.