Label Outlets With Breaker Numbers
Writing the breaker number on the back of each cover plate so the next job starts with the answer.
Tap Panel Knockouts Out Side-to-Side — Never Toward the Next Ring
A knockout comes out clean with a flathead on the divots and light archaeologist taps, rocking side to side. Working upward into the concentric ring breaks it — and then you're shopping for spacer rings.
breaker box punch outs, electrical knockout removal, junction box knockouts
The Problem
Panel and disconnect knockouts look like you should just hit them — and that's how the concentric rings around them get bent or broken, leaving a hole too big for the connector and a gap that isn't legal to leave open. The metal gives clues about where it wants to break; most people never look for them.
The Technique
An electrician's sequence, with only a flathead screwdriver and lineman's pliers:
- Use a sturdy flathead — an impact-rated one. A light-duty screwdriver's tip deforms and chews the metal instead of driving it.
- Find the divots. The small dimples stamped around the knockout are the engineered weak points — those are your targets.
- Tap like an archaeologist, not a demolition crew. Light hammer taps on the divots to start the knockout moving.
- Rock it side to side. Tap one side, then the other, back and forth — the tabs fatigue and let go cleanly. Don't work upward into the surrounding ring: pressure that direction breaks the next ring out, the one you wanted to keep.
- Twist out the last connection with lineman's pliers once the slug is hanging, and fit your connector.
If a ring does break, spacer (reducing) rings exist to rebuild the opening — fit one flush, oriented correctly, and carry on.
Pro tip: On stubborn multi-ring knockouts, some electricians drill through the little weld tabs holding the slug instead — a 3/16 bit on each tab and the slug falls out with one tap, with zero risk to the neighboring rings.
Safety note: Knockout work belongs on a dead panel. De-energize and verify with a tester before putting a screwdriver anywhere inside an enclosure — a slip with steel in each hand is not a place to meet a live bus.
Electrical, plumbing, and structural work may be regulated where you live — check local code before you start, and note that a permit may be required. More in our disclaimer.
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