Im an electrician. The way to protect the outlets is to replace the first outlet in the circuit with the GFCI. The way it works is there is a sensor that monitors the amperage goin back on the neutral so it is protecting you, they trip at 4 to 6 milliamps. If your planning on replace the panel, it is more expensive but you can throw in the GFCI breakers. They are more expensive but it saves on time and labor.
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