Apprentice path · Stage 19: Habits that outlast you · Lesson 67

Drilling: know what is behind

Before you make a hole, find out what is on the other side of the surface you are about to go through.

Why this matters on the job

A drill bit that finds a live conductor inside a wall is an arc, a shock, or both, and you are holding the tool. Water and gas services are in there too.

How to think about it

  1. Check for concealed electrical and other services first.
  2. Use the approved locating method and the approved work method.
  3. Control the dust, the debris and who has access to the area.

Worked through

A locator gives you information, not certainty. It tells you something is there, or that it did not detect anything -- which is not the same as nothing being there. The approved work method exists to cover the gap between those two, and it is the reason the answer to an uncertain wall is to stop rather than to go slowly.

Check yourself: The locator shows nothing and you are fairly sure the wall is empty. Drill?

Answer: No. Stop when the wall contents are uncertain instead of making a blind hole.

Fairly sure is not established. The locator not detecting something is a weaker statement than the wall being empty, and the cost of being wrong is paid instantly and by you.

Watch out for: Treating the locator as the whole method. It is one input; the approved locating and work method is the procedure, and controlling dust, debris and access is part of the same job rather than cleanup afterwards.
Take the free 15-question readiness check

No card. No account needed to start. Score by topic against the 70% mark.

← Lesson 66All lessonsLesson 68 →

Written from the owner's poster for this lesson. Nothing added beyond what the poster states.

Written for Texas apprentices as free study material. The Texas apprentice licence is an application, not an exam (Occupations Code 1305.161), and nothing here counts as apprenticeship hours or continuing-education credit. VoltMark is not affiliated with, endorsed by, or sponsored by NFPA, PSI, TDLR, or any state or local licensing authority. Always follow your employer's safety programme and your supervising electrician.