Yes, you can place a GFCI receptacle on each leg of a multiwire branch circuit (MWBC) if you've properly pigtailed the neutrals. Here's a breakdown of why and important considerations

Why it works with pigtailed neutrals:
GFCI Functionality

GFCI receptacles work by monitoring the current flowing to and from the device they protect. If there's an imbalance (a difference of 5mA or more), it indicates current is leaking somewhere, potentially through a person. The GFCI then trips, interrupting the circuit.

Neutral Return Path

With a properly pigtailed neutral on an MWBC, each GFCI will have its own dedicated neutral return path back to the neutral bar in the panel. This is crucial. The GFCI needs to see all the current returning on its dedicated neutral.

Preventing Nuisance Tripping

Without pigtailing, the current from one leg of the MWBC could return on the neutral connected to the GFCI on the other leg. This would create an imbalance that the GFCI would interpret as a ground fault, causing it to trip unnecessarily. Pigtailing the neutrals ensures each GFCI only sees the current associated with the devices on its leg of the MWBC.

Important Considerations and Best Practices


Pigtailing is MANDATORY

You absolutely must pigtail the neutrals. Do not rely on the receptacle's neutral terminals to act as a splice point for the neutral. This is true for any* situation, not just with GFCIs, but it's especially critical here.2.

Proper Wiring

Ensure the GFCI receptacles are wired correctly. The line (hot) and neutral wires from each leg of the MWBC connect to the 'LINE' terminals on their respective GFCIs. The load side of the GFCI (if used to protect downstream receptacles) connects to the 'LOAD' terminals.

Do not connect the neutral of one leg of the MWBC to the 'LINE' neutral terminal of the GFCI on the other leg.3. Common Trip vs. Individual Trip

You can choose to have each GFCI trip independently or wire them so that if one trips, it trips the other(s). The most common, and generally preferred, is to have them trip independently.4.

Testing

After installation, thoroughly test each GFCI receptacle to ensure it trips correctly when the test button is pressed. Also, test any downstream receptacles protected by the GFCI.5.

Professional Advice

If you're not completely comfortable working with electrical wiring, it's always best to consult a qualified electrician. MWBCs can be tricky, and improper wiring can be dangerous.6.

Arc Fault Circuit Interrupters (AFCIs)

Consider the potential need for AFCIs. Some jurisdictions now require AFCI protection on certain circuits (e.g., bedroom circuits). If AFCI protection is required, you'll typically need to use an AFCI breaker in the panel to protect the entire circuit. Using both AFCIs and GFCIs on the same circuit can sometimes lead to nuisance tripping.

In summary, with correctly pigtailed neutrals, it's perfectly fine (and often necessary) to install GFCI receptacles on each leg of an MWBC. Pigtailing is the key to avoiding nuisance tripping. Flag for review