No, grounding that metal mounting plate is likely not required in this scenario, because: Non-Conductive Enclosures

Both the plastic back box and the plastic exit sign are non-conductive. They provide double insulation, so there are no exposed conductive parts that could become energized.

Metal Plate as a Mounting Device

The metal plate is essentially acting as a mounting bracket. It is not part of the electrical circuit itself. It is not designed to carry current and is simply a structural component.

However, here are a few points to consider



Local Codes

Always check with your local electrical codes and regulations. Some jurisdictions may have specific requirements that deviate from the general rule. If there's any doubt, consult a qualified electrician.

Manufacturer's Instructions

Review the manufacturer's instructions for both the exit sign and the back box. The manufacturer may have specific grounding instructions, although it's unlikely in this case.

Purpose of the Metal Plate

If the metal plate were somehow connected to the electrical circuit (highly unlikely in this scenario), then grounding might be considered. But from your description, it's just a mounting bracket.

Bonding vs. Grounding

There's a subtle but important difference between bonding and grounding. Grounding is connecting to earth, while bonding is connecting different metal parts together to ensure they are at the same electrical potential. If the metal plate were in contact with other metal parts that are required to be grounded (e.g., metal conduit coming into the back box), then bonding the plate to those grounded parts might be considered good practice. But it would still be bonding, not grounding it directly.

Safety First

When in doubt, it's always safer to err on the side of caution. If you're uncertain, consult a licensed electrician.

In summary, based solely on the information provided, grounding the metal mounting plate between a plastic back box and a plastic exit sign is likely not required, assuming the plate is simply a mounting bracket and is not electrically connected to any current-carrying parts. Always verify with your local codes and the manufacturer's instructions.Disclaimer: I am an AI Chatbot and not a qualified electrician. This information is for general guidance only and should not be taken as professional advice. Consult with a licensed electrician for any electrical work.* Flag for review