5×5 Risk Matrix Explained: How to Rate Hazards for RAMS

How the 5×5 Matrix Works

The 5×5 risk matrix is the standard scoring method in UAE RAMS documents — it is the approach set out in Abu Dhabi's OSHAD Codes of Practice and accepted in Dubai by Dubai Municipality, Trakhees and the major developers. Every hazard in your risk assessment gets two numbers: a likelihood rating from 1 to 5 and a severity rating from 1 to 5. Multiply them and you get the risk score, from 1 to 25.

The score is not decoration — it drives decisions. It tells you which hazards demand the strongest controls, it shows the reviewer that you prioritized correctly, and it gives you the before-and-after comparison that every RAMS reviewer looks for: the risk before your controls, and the risk that remains after them.

The Likelihood Scale (1–5)

Likelihood asks: how probable is it that this hazard actually harms someone during this work, given the site, the crew and the duration? The five levels:

• 1 — Rare: would only happen in exceptional circumstances
• 2 — Unlikely: could happen, but not expected
• 3 — Possible: might well happen during the work
• 4 — Likely: will probably happen without controls
• 5 — Almost certain: expected to happen repeatedly

The Severity Scale (1–5)

Severity asks: if it does happen, how bad is the worst credible outcome? Rate the realistic worst case for the hazard, not the everyday near miss:

• 1 — Negligible: no injury or trivial first-aid case
• 2 — Minor: minor injury, short absence
• 3 — Moderate: lost-time injury, medical treatment
• 4 — Major: serious injury, long-term harm
• 5 — Catastrophic: fatality or multiple serious injuries

Risk Bands: From Score to Action

Multiplying likelihood by severity gives a score from 1 to 25, and the score falls into one of four bands. The default banding used across UAE submissions:

• 1–4 — Low: risk is broadly acceptable; manage through routine controls and monitoring
• 5–9 — Medium: tolerable if controls are in place and followed; monitor and improve where practicable
• 10–16 — High: work should not proceed without additional controls; senior review required
• 17–25 — Critical: stop — the work must not start or continue until the risk is reduced

Inherent vs Residual Risk — and ALARP

Every hazard in a RAMS is scored twice. The inherent (initial) risk is the score before any control measures — what the hazard looks like if you simply walked in and started work. The residual risk is the score that remains after your control measures are applied. Both numbers go in the hazard table: the inherent score shows you understood the real danger, the residual score shows your controls actually reduce it.

The target for residual risk is ALARP — as low as reasonably practicable. You do not have to eliminate every risk to zero; you have to reduce it until the cost and effort of further reduction would be grossly disproportionate to the benefit. In practice that means high and critical inherent risks must come down to medium or low residual bands through credible controls — and if a residual score stays high, that is a signal to strengthen the controls or rethink the method, not to submit and hope.

The Hierarchy of Controls

Controls are not equal. When you bring a score down, the measures you choose should sit as high as possible on the hierarchy of controls:

• Eliminate — remove the hazard entirely (de-energize the circuit instead of working live)
• Substitute — replace it with something safer (battery tools instead of 230V)
• Engineering controls — isolate people from the hazard (guardrails, local exhaust ventilation, RCD protection)
• Administrative controls — change how people work (permits to work, safe isolation procedure, job rotation in heat)
• PPE — the last line, never the only line (arc-rated clothing, FFP3 respirators, harnesses)

Worked Example 1: Electric Shock on Live Conductors

Take the first hazard in any LV electrical installation RAMS: electric shock from contact with live conductors. Severity is 5 — contact with live parts can kill, so the worst credible outcome is catastrophic. Without controls, on a fit-out with multiple live boards around you, contact is likely: likelihood 4. Inherent risk = 4 × 5 = 20 — critical. Work must not proceed like this.

Now apply controls from the top of the hierarchy: eliminate the live state through a safe isolation procedure — isolate, lock out and tag out (LOTO), prove dead with a GS38-compliant tester; restrict the work to DEWA-enrolled electricians; use insulated tools and gloves near any parts that cannot be de-energized. With the circuit proven dead, contact with live conductors becomes rare: likelihood 1. Residual risk = 1 × 5 = 5 — medium, because the severity stays 5 but the probability is now minimal. That before-and-after pair, 20 → 5, is exactly what a reviewer wants to see.

Worked Example 2: Silica Dust During Chasing

Chasing walls for cable routes generates respirable silica dust. Worst credible outcome with sustained exposure is serious long-term harm — severity 4. During a chasing-heavy week without controls, exposure of the installer is possible to likely — likelihood 3. Inherent risk = 3 × 4 = 12 — high.

Controls: engineering first — wet cutting or local exhaust ventilation at source; administrative — exclude other trades from the immediate area; PPE as the last line — FFP3 respiratory protection and eye protection. With extraction at the source, meaningful exposure becomes rare — likelihood 1. Residual risk = 1 × 4 = 4 — low. Note what did not happen: the severity did not move. Silica remains harmful; what changed is the probability of harmful exposure. Ratings that magically drop both numbers are a red flag to experienced reviewers.

Worked Example 3: Falling Objects During Overhead Containment Work

Installing cable tray in ceiling voids puts people below at risk from dropped tools and offcuts. A dropped tool from height can cause a major injury — severity 4. Without controls, during overhead work above active areas, drops are possible — likelihood 3. Inherent risk = 3 × 4 = 12 — high.

Controls: exclude — set an exclusion zone below the work; engineering — toe boards and tool lanyards; administrative — hard hats and coordination with other trades. A dropped object reaching someone becomes unlikely — likelihood 2, and with lanyards most drops never fall at all. Residual risk = 2 × 4 = 8 — medium, or lower if the exclusion zone is fully enforced. If your method cannot enforce the exclusion zone — for example in an occupied corridor — that is when you escalate to scheduling the work out of hours.

Skip the Blank Matrix — Generate It

In RamsProof every work-type template already carries hazards scored on the 5×5 matrix exactly this way: inherent likelihood and severity, controls written to the hierarchy, and residual scores. The review step of the wizard shows you each hazard's before-and-after ratings — a critical 20 dropping to a controlled 5, a high 12 to a low 4 — so you and your competent person calibrate the numbers to your site instead of inventing them from scratch.

Pick your work type, answer five wizard steps, and download a RAMS whose risk table already speaks the reviewer's language.

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