Lesson · 26 min

The Focus Four Hazards

Falls, struck-by, caught-in, and electrocution account for most construction deaths. These four are where the attention goes.

By the end of this lesson you can

Name the Focus Four and why they are singled out
Describe fall protection requirements and when they trigger
Identify struck-by and caught-in hazards on a site
Apply basic electrical safety, including lockout/tagout

📘 Reading Lesson

Lesson Notes

Read through the key concepts before you try the challenge.

Four hazards, most of the fatalities

On the job

You are walking a site for the first time.

There is a lot to look at. Focusing on everything means focusing on nothing — so start with the four categories that account for the majority of construction deaths, because if those are controlled the site is usually being run properly.

Your task: Learn the four, and learn what each looks like before it causes harm.

Hazard	Typical cause	Primary control
Falls	Unprotected edges, holes, improper ladder and scaffold use	Guardrails, covers, personal fall arrest
Struck-by	Vehicles, falling objects, swinging loads	High-visibility clothing, hard hats, exclusion zones, toe boards
Caught-in / between	Trench collapse, unguarded machinery, pinch points	Protective systems, machine guarding, lockout/tagout
Electrocution	Contact with power lines, damaged cords, missing grounding	De-energizing, GFCI, clearance distances, lockout/tagout

The Focus Four

Falls are the leading cause of death in construction, and the trigger height in construction is generally six feet above a lower level. General industry uses four feet. That difference matters and is commonly confused — verify the standard for the work you are actually doing rather than assuming one figure covers everything.

Trenching deserves specific mention because it kills quickly and the danger is not intuitive. A cubic yard of soil weighs roughly as much as a small car, and a collapse gives no warning and no time to escape. Protective systems — sloping, shoring, or shielding — are generally required at five feet, and a competent person must inspect the excavation daily and after any rain.

Worked example

Assessing a work-at-height task

You are asked to work on a flat roof eighteen feet up with an unprotected edge.

1
Ask whether the fall hazard can be removed rather than protected against.
The hierarchy of controls puts elimination first. Doing the work from the ground, or from a lift, removes the hazard entirely — which is always better than managing it. This question is skipped far too often.
2
If it cannot, check what protection is in place at the edge.
Guardrails protect everyone passively, with nothing to put on and nothing to remember. That makes them more reliable than equipment depending on each worker using it correctly every time.
3
If personal fall arrest is the answer, check the whole system, not the harness.
A harness is one part. You need an anchor rated for the load, a lanyard or lifeline, and enough clearance below that you stop before hitting anything. A correctly worn harness with insufficient fall clearance does not save you.
4
Inspect your equipment before every use.
Cuts, fraying, chemical damage, or evidence a component has already arrested a fall all mean the equipment is out of service. A harness that has taken a fall is discarded, not reused.
5
If protection is absent, stop and raise it.
This is what the rights in the previous lesson are for. An unprotected leading edge at eighteen feet is a fatality waiting for a moment of inattention, and you are entitled to say so.

Result: Either the hazard is removed, or a complete and inspected protective system is in place before work starts.

Eliminate first, protect passively second, and treat personal fall arrest as a whole system rather than a harness.

Check your understanding

In construction, at what height does fall protection generally become required?

Challenge

Apply what you've learned in this lesson.

OSHA publishes the standards and the fatality data free.

Find OSHA's construction fall protection standard and note the trigger height and the acceptable methods.
Research the hierarchy of controls and write out all five levels in order.
Find the trenching requirements: the depth at which protective systems are required, and who must inspect.
For a workplace you know, identify one hazard in each Focus Four category and the control that applies to it.

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