Electrical Code Requirements

According to the National Electrical Code (NEC), multiple GFCIs can be used in series as long as: Each GFCI is properly wired and installed. The downstream GFCI is rated for the same or higher amperage as the upstream GFCI.

Protection Mechanism

GFCIs work by sensing any difference in current between the hot and neutral wires. If a fault occurs and current starts flowing to ground, the GFCI will trip, breaking the circuit and preventing electrical shock.

Current Flow in Series

When GFCIs are connected in series, the current flows through each GFCI in turn. If a fault occurs, the GFCI closest to the fault will trip first, protecting the circuit downstream from it. The other GFCIs will remain energized, providing protection to the rest of the circuit.

Site Safety Manager's Concern

Your Site Safety Manager's concern may stem from a misinterpretation of the NEC's requirement that each GFCI in series be rated for the same or higher amperage. This requirement ensures that the upstream GFCI has enough capacity to protect the downstream GFCIs and the connected equipment.

Your Theory

Your theory is correct. Both GFCIs will provide protection to the equipment connected downstream from them. However, it's important to note that the downstream GFCI is the primary protection device for that portion of the circuit. If the upstream GFCI trips, the downstream GFCI will remain energized until it also trips.

Conclusion:

Based on the electrical code requirements and the protection mechanism of GFCIs, it is safe to use multiple GFCIs in series, provided they are properly rated and wired. Your Site Safety Manager's concern is likely due to a misunderstanding of the code. It's recommended to clarify these concerns with him and provide documentation from the NEC if necessary. Flag for review