The POSS shares three sections with EEI's maintenance test. Figural Reasoning is what sets it apart

The POSS is reported to include Mechanical Concepts, and our mechanical practice test covers the same ground: levers, gears, fluids, heat and simple circuits, each with a drawing. Our reasoning test adds number work and reading passages, which touch the Mathematical Usage and Reading Comprehension parts.

Figural Reasoning, the part that sets the POSS apart, is a shape and pattern test we only cover on our separate abstract reasoning page, and none of our tests copies EEI's timings or its combined score. EEI's Test #5100 information guide is the better guide to format.

EEI publishes two power plant batteries that look alike from the outside. The POSS is for operators. The MASS, the Power Plant Maintenance Positions Selection System, is for mechanics, electricians and other maintenance staff. Prep sites say both share Mechanical Concepts, Mathematical Usage and Reading Comprehension.

The difference is one section. Prep sites describe Figural Reasoning on the POSS and Assembling Objects on the MASS, and describe the MASS as about 118 questions in two hours. If your invitation names Test #5100 or operator selection, you are on the POSS, and your preparation should include pattern questions.

Figural Reasoning asks you to spot a rule in a series or grid of shapes and choose the piece that continues it. It feels nothing like the plant work you are applying for, which is exactly why candidates neglect it. Yet operators spend shifts reading panels and trends for the one indicator that has changed.

Practise systematically: list every feature that could change, such as number, shading, rotation and position, and test each one. Our free abstract reasoning test gives you this kind of item, and a week of short daily sets is usually enough to stop pattern questions feeling strange.

Prep samples for EEI's mechanical sections cover levers, pulleys and mechanical advantage, the physics behind hoists, valves and rotating plant. We found no published breakdown of Mathematical Usage for the POSS, so prepare for short computation: fractions, percentages, simple formulas and rearranging an equation.

Both reward fluency more than depth. If you have been out of school for a while, rebuild your arithmetic first, then spend most of your time on mixed mechanical drawings. Our mechanical aptitude test gives you 55 picture-based items on one clock, and the mechanical test guide explains the rules behind them.

Operators work from procedures, logs and permits, so the reading section matters more than it looks. We found no published sample passage for the POSS, so practise on technical and workplace text and answer from what the text says, not from outside knowledge.

Answer only from the passage. When two options both sound right, pick the one the text directly supports, and be wary of answers that use words like always or never unless the passage does too.

Prep guides describe each section being scored on its raw number correct, then combined into one overall result. That means a strong mechanical score can carry a weaker pattern score, and steady effort across all four parts beats brilliance in one.

EEI and the employers we found do not publish a passing score for the POSS. If you are not selected, ask the employer how long you must wait before testing again, because we found no single published rule.

These come from anonymous reviews, university careers pages and prep guides. They often disagree, and Power plant operator (EEI POSS) has not confirmed them. Read them as leads, not rules.

• Candidates on the NukeWorker forum report sitting a four-section POSS at Entergy, and others say older versions had more parts.
• Prep sites describe the POSS and MASS as proctored multiple-choice batteries of about two hours each.
• Prep guides note that Figural Reasoning appears only on the operator battery, so it is the section least covered by general trades prep.