EEI MASS Test – Full Guide and Free Practice for 2024

A 118-questions test assessing potential power plant maintenance candidates in 4 very different cognitive abilities.

The 4 sections of the EEI MASS Test (math, spatial, mechanical, and reading comprehension), are the cornerstones of psychometric testing. Each section requires highly different skills to ace.

This guide provides you with everything you need to ace the MASS test, including a free sample test, a complete test overview, and tailored tips.

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Basic Details

Math, reading, spatial, mechanical
118 questions
72 minutes

What Is the EEI MASS Test?

The EEI MASS Test (Power Plant Maintenance Positions Selection System) is a pre-employment assessment battery used to screen power plant maintenance positions. The test is designed and administered by the Edison Electric Institute (EEI).

The EEI MASS assesses 4 cognitive abilities designed to evaluate how well a candidate will perform on maintenance jobs.

Test Structure and Question Format

The EEI MASS Test is divided into 4 sections, each with its own content and time limit:

  • Assembling Objects – 20 questions in 15 minutes.
  • Mathematical Usage – 18 questions in 7 minutes.
  • Mechanical Concepts – 44 questions in 20 minutes.
  • Reading for Comprehension – 36 questions in 30 minutes.

Let’s describe each of these sections in a bit more detail.

You will find detailed answers for the questions below (+more) in the Free Practice section.

Assembling Objects

The Assembling Objects section assesses your spatial reasoning abilities. The questions in this section include a disassembled object that you should visualize in its assembled form. Dots with letters indicate where each part should go.

EEI Assembling Objects Sample 1

Mathematical Usage

The Mathematical Usage section assesses your ability to calculate quickly and accurately via unit conversion questions. You have 7 minutes to solve 18 questions.

EEI Mathematical Usage Sample 2

Pro Tip

The Mathematical Usage section is probably the section in which time poses the greatest challenge. Focus on improving your solving speed to succeed.

Mechanical Concepts

The questions in the Mechanical Concepts section assess your understanding of basic mechanics and electricity. The questions do not require calculations, and therefore can be solved quickly. The section contains 44 questions to be solved in 20 minutes.

EEI Mechanical Concepts Sample 1

Pro Tip

The variety of questions in the Mechanical Concepts section requires you to understand the major physical principles at the heart of the test. Examples are law of the lever, centrifugal force, fluid mechanics, etc.

Reading for Comprehension

The last section measures your ability to understand and interpret text. You will be presented with a short piece of text (~400 words) and will be required to answer 9 questions about it.

4 such texts will be given throughout the section, so 36 questions overall. The total time limit is 30 minutes.


Check out the Free Practice section to try some of these questions yourself.

Test Interface

The MASS test interface is easy to follow and is similar to that of other EEI tests such as CAST, TECH, or POSS. Here are 4 basic things you should know about the test:


Separate Sections

Each section on the EEI MASS Test is conducted separately, with its own content and time limit. This means that you will not be able to use spare time from longer sections such as Reading for Comprehension (30 minutes) for shorter sections like Mathematical Usage (7 minutes).  Make sure you are well-prepped for each section’s specific time constraints.

You Can Move Between Questions

The MASS test allows you to move back and forth between questions or skip them and get back to them later. That allows better time management and development of solid solving methods while preparing.

No Points Reduced for Wrong Answers

The MASS Test, as all of EEI’s tests, does not reduce points for wrong answers. So, if you don’t know the answer, it’s better to guess than not to answer at all.

Calculators Are Not Allowed

Only 18 questions out of the test’s 118 require calculations, so it’s not as major of an issue as you might think. However, since calculators are not allowed, make sure you have mastered pen-and-paper calculation to maximize your chances of success.

Free Practice

This free practice test includes 10 questions, and is designed to get you familiar with the types of questions on the EEI MASS Test and their level of difficulty.

You will also find answers, explanations, and tips for success.

Good luck!

Section 1 – Assembling Objects

Question 1

EEI Assembling Objects Sample 1

Answer and Explanation

The correct answer is B.

EEI Assembling Objects Sample 1 - Answer

Question 2

EEI Assembling Objects Sample 2

Answer and Explanation

The correct answer is D.

EEI Assembling Objects Sample 2 - Answer

Section 2 – Mathematical Usage

Question 3

EEI Mathematical Usage Sample 1

Answer and Explanation

The correct answer is B.

3 acres = [3 x 160] square rods = [3 x 160 x (0.252)] square chains = 30 square chains.

Pro Tip

When converting square units – don’t forget to square!

Question 4

EEI Mathematical Usage Sample 2

Answer and Explanation

The correct answer is C.

0.25 hogshead = [0.25 x 63] gallons = [0.25 x 63 x 3.785] liters = [0.25 x 63 x 3.785 x (1/34.065)] firkins = 1.75 firkins.

Question 5

EEI Mathematical Usage Sample 3

Answer and Explanation

The correct answer is A.

8 fathoms = [8 x 6] feet = [8 x 6 x (1/66)] chains = [8 x 6 x (1/66) x (1/0.25)] rods = [8 x 6 x (1/66) x (1/0.25) x (1/40)] furlongs = 0.73 furlongs

Section 3 – Mechanical Concepts

Question 6

EEI Mechanical Concepts Sample 1

Answer and Explanation

The correct answer is B.

In a pipe where the flow is uniform, the narrower the pipe, the faster the flow. The underlying physical principle is the volumetric flow rate formula.

Q = V x A

  • Q = volumetric flow rate
  • V = flow velocity
  • A = pipe cross-section area

Since Q is constant along the entire pipe, if A is lower, V must be higher.

Pro Tip

While the mechanical concepts section does not require previous knowledge, being familiar with basic physics is going to give you a major advantage.

Question 7

EEI Mechanical Concepts Sample 2

Answer and Explanation

The correct answer is A.

When two cars travel side by side, the one doing the larger curve is going faster. The underlying physical principle is angular and linear velocity.

V = w x R

  • V = Linear velocity (how fast the car is moving in a straight line)
  • w = Angular velocity (how fast the car is “rotating” along the center of the circle)
  • R = The distance from the imaginary center of the circle.

Since Car A and Car B have the same angular velocity (they travel side by side), but Car A is farther from the center, its linear velocity is greater.

Tip: If you still haven’t wrapped your head around this, think about a VERY wide circle, with two cars travelling inside, with a line between them. Clearly, the car in the outer lane will have to travel much faster than the one in the outer lane to keep up.

EEI Mechanical Concepts Sample 3 - Explanation

Question 8

EEI Mechanical Concepts Sample 3

Answer and Explanation

The correct answer is B.

A spring’s stiffness is proportional to its length. The longer the spring, the less stiff it is. The underlying principle is Hooke’s Law.

Section 4 – Reading for Comprehension

Use the following passage for questions 9-10.

Safety Measures in Electrical Work

Electricians work with potentially hazardous electrical systems, and ensuring their safety is paramount to prevent accidents and injuries. Implementing effective safety measures is crucial in minimizing risks and creating a secure working environment.

Wearing appropriate Personal Protective Equipment (PPE) is fundamental for an electrician’s safety, including insulated gloves, safety glasses, flame-resistant clothing, and steel-toed boots. PPE provides a protective barrier against electric shocks, burns, and other potential hazards. However, proper safety measures are designed to ensure that PPE remains only a backup plan.

Using the right tools for the job is crucial in that sense. Insulated and non-conductive tools help prevent electric shock, and regular maintenance ensures that tools remain in good working condition. Compliance ensures that electrical installations meet safety standards, reducing the risk of accidents and ensuring the longevity of the electrical systems. Having first aid kits, fire extinguishers, and other equipment in the worksite ensures a prompt and effective response in case of accidents or injuries.

Professional knowledge is an essential component of safe work. Hence, electricians must undergo proper training and obtain the necessary certifications. While in the case of other jobs this training is designed mostly for professional reasons, the electrician codes and regulations were designed to prevent serious injury and death. Therefore, an in-depth familiarity with them is non-negotiable in this case.  This requirement translates to a legally mandated official certification in nearly all countries and states, yet the specifications may vary. This includes but is not limited to adequate knowledge of electrical systems, safety protocols, and emergency procedures. Some regulatory bodies also require first aid training.

As every working environment has its own unique features, a thorough risk assessment should be carried out by a certified electrical engineer or electrician before commencing any electrical work. Identifying potential hazards and implementing preventive measures ensures a safer work environment, including assessing the voltage levels, potential exposure to live circuits, and any other factors that may pose a risk.

The usage of lockout/tagout procedures is another highly important safety measure. These procedures involve isolating energy sources and using locks or tags to protect electricians from unexpected electrical discharges. De-energization of panels should be used whenever possible, as well as proper labeling of circuits for quick and accurate identification.

Additional safety measures should be implemented for electrical work at heights. This may include the use of harnesses, guardrails, and proper scaffolding. Implementing these measures helps prevent falls and the associated injuries. Safety organizations and labor unions regularly conduct training and certification plans for those working at height.

Question 9

In which paragraph would it be most relevant to describe new patented pliers especially designed for electricians?

  1. Paragraph 1
  2. Paragraph 2
  3. Paragraph 3
  4. Paragraph 4
  5. Paragraph 5

Answer and Explanation

The correct answer is C.

Each paragraph of the text deals with a different aspect of safety measures for electricians. Paragraph 3 focuses on “the right tools for the job”, a category that is most appropriate for pliers. Paragraph 2, which describes Personal Protective Equipment (PPE), is less relevant, as it focuses on equipment whose main purpose is to protect the electrician.

Question 10

Which of the following measures could be described as “the last line of defense” in an electrician’s work?

  1. Risk assessment
  2. An official certification
  3. Proper work tools
  4. PPE
  5. Professional knowledge

Answer and Explanation

The correct answer is D.

According to the text: proper safety measures are designed to ensure that PPE remains only a backup plan.” That is, if all other safety measures have failed, PPE is the last resort to prevent injury or death. Careful adherence to safety protocols should ensure that electricians do not face a situation in which their safety depends on their PPE.

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