Don't Assume GFCI Line and Load Positions — Check the Labels

The Problem

When swapping a GFCI outlet, it's tempting to just note which wire sat on which screw on the old device — black wire top, white wire top, and so on — and wire the new one to match those same physical positions. That only works if the new GFCI is built the same way as the old one, and manufacturers don't agree on which side is Line and which is Load.

The Technique

1. Before disconnecting anything, find the "LINE" and "LOAD" labels printed on the back of the old outlet — not just which screws the wires happen to be on. Line is where power comes in from the breaker; Load is where it continues on to the next receptacle.
2. Note which physical position (top or bottom) each label sits at on this specific device.
3. When you unbox the new GFCI, check its own LINE/LOAD labels the same way. Don't assume the layout matches the old device — different manufacturers put Line and Load on opposite ends even though the outlet looks identical and the ground prong sits in the same spot.
4. Wire the new outlet by matching Line-to-Line and Load-to-Load per its own labels, not by copying the old device's screw positions.