Understanding GFCI Outlets: Series Wiring and Safety

When it comes to protecting electrical circuits, GFCI outlets are a key component. However, there are some common misconceptions and questions about how to properly wire and position these devices. In this article, we will address whether it's necessary or advisable to put two GFCI outlets in series and explore the best practices for wiring GFCI outlets in a residential setting.

Why You Should Not Use Two GFCI Outlets in Series

The primary reason to avoid placing two GFCI outlets in series is to prevent nuisance trips. GFCI (Ground-Fault Circuit Interrupter) outlets are designed to protect against electrical shock by shutting off power as soon as a ground fault is detected. When installed in series, both outlets must have power to function, and a fault in one GFCI can cause both to trip, leading to unnecessary downtime and inconvenience.

When to Use GFCI Outlets

GFCI outlets can be beneficial in specific situations, such as:

To protect multiple outlets on the same circuit. To protect outdoor outlets and bathrooms, where the risk of moisture and shock is higher.

For example, you might install a GFCI on the back porch to protect the entire circuit, including the front porch, if the protective domain extends that far.

Multiple bathrooms on different floors can be protected by a single GFCI, but all outlets within the protected domain need to be wired correctly.

Proper Wiring of GFCI Outlets

While you are not required to wire GFCI outlets in series, correct wiring is crucial for their optimal function and safety:

1. Parallel Connection

Instead of series wiring, GFCI outlets can be connected in a parallel configuration, which involves:

Using a continuous wire to connect the Line side of the first outlet to the Line side of the next outlet. Connecting the Load side of the first outlet to the Line side of the next outlet.

This setup allows the GFCI to protect all the outlets on the same parallel line.

2. Correct Wiring for a Single GFCI Protecting Multiple Outlets

For a single GFCI protecting multiple outlets:

At the first receptacle: Pigtail the hot, neutral, and ground wires to the Line side only. Ensure nothing connects to the Load side at the first outlet. At the second GFCI receptacle downstream: Connect the incoming power feed from the previous outlet to the Line side and anything downstream leaving that box to the Load side for GFCI protection.

This arrangement ensures that the second GFCI is unnecessary and often causes more hassle than it alleviates.

Do GFCI Outlets Need Individual Feeds?

Yes, GFCI outlets require individual feeds. This means:

There should be a separate wire connection for incoming power and outgoing power. The COM (common) wires are common across all outlets.

Proper wiring ensures that each GFCI outlet can function independently and avoid interfering with one another.

Conclusion

While it is technically possible to wire two GFCI outlets in series, it is not recommended due to the potential for nuisance trips. Instead, use the correct parallel or daisy-chain wiring configuration to ensure optimal protection and minimize inconvenience. Always consult the manufacturer's instructions or a licensed electrician for correct installation and wiring.