Power Plant Maintenance Selection System Exam

This overview includes information to help you prepare for the Power Plant Maintenance Positions Selection System, commonly called the MASS test. You will find details about the test format, registration, scoring, test-day procedures, preparation, and study resources.

Questions

118 multiple-choice questions

Testing Time

About 2 hours

Aptitude Tests

4 separately timed sections

Test Developer

Edison Electric Institute

Exam Background and Purpose

The Power Plant Maintenance Positions Selection System, or MASS, is a pre-employment aptitude test battery developed by the Edison Electric Institute. Electric utilities use the test to help evaluate applicants for maintenance and craft positions.

Positions that may require MASS testing include electrical, mechanical, instrumentation, welding, machining, pipefitting, rigging, and other power plant maintenance jobs. The exact positions covered depend on the hiring company.

Key point: MASS is used for power plant maintenance and craft positions. POSS is a different EEI test battery used primarily for power plant operator positions.

MASS Test Overview

The MASS test contains 118 multiple-choice questions divided among four separately timed aptitude tests. The four timed sections total approximately 67 minutes.

The complete testing appointment may take about two hours when check-in, instructions, practice questions, administrative activities, and breaks are included.

EEI test batteries can be delivered in different formats. Your employer may administer MASS on paper, by computer, or through another approved testing arrangement.

MASS Sections and Timing

Aptitude Test Questions Time Skills Measured
Reading Comprehension 36 30 minutes Reading and understanding information similar to material found in power plant training and safety manuals
Mechanical Concepts 44 20 minutes Applying mechanical principles involving forces, motion, gears, pulleys, fluids, tools, and equipment
Assembling Objects 20 10 minutes Visualizing how separate pieces fit together to form a correctly assembled object
Mathematical Usage 18 7 minutes Solving basic mathematical problems involving arithmetic, fractions, decimals, percentages, proportions, conversions, and formulas

The test is aggressively timed. Mathematical Usage allows an average of about 23 seconds per question, while Mechanical Concepts allows an average of about 27 seconds per question.

Registration, Costs, and Locations

You cannot register for the MASS test directly through EEI. The test is administered as part of an employer’s hiring or selection process.

Begin by applying for a position with an electric utility or another employer that uses the MASS battery. If the employer selects you to continue in the hiring process, it will provide the testing invitation, appointment details, and instructions.

Registration Basics

  • EEI does not schedule MASS appointments directly for applicants.
  • The hiring company determines who is invited to test.
  • Testing may take place at a company facility, testing center, training facility, or another approved location.
  • The delivery method may vary by employer.
  • Follow the instructions in the employer’s invitation rather than relying on general online information.

How Much Does the MASS Test Cost?

There is no universal applicant fee for the MASS test. Because MASS is normally administered as part of an employer’s hiring process, many applicants are not charged a separate testing fee.

Any fee, rescheduling charge, or missed-appointment policy is determined by the company or organization administering your test.

What Should I Expect on Test Day?

Test-day procedures vary by employer and delivery method. Read the invitation carefully and contact the hiring company when an instruction is unclear.

Test-Day Checklist

  • Arrive before the appointment time stated in your invitation.
  • Bring the identification required by the hiring company.
  • Make sure the name on your identification matches your application and testing record.
  • Bring the testing invitation or confirmation when instructed.
  • Do not bring notes, study materials, or unauthorized electronic devices into the testing area.
  • Do not assume you may use a personal calculator. Follow the instructions provided by the employer.

How Is the MASS Test Scored?

Performance on the four aptitude tests is combined into an overall cognitive index. Employers use that result to help estimate whether an applicant is likely to succeed in training and perform effectively in covered maintenance positions.

EEI does not publish one universal passing score for every applicant. Each participating employer establishes its own selection standards and determines how MASS results are used with the rest of the hiring process.

A score accepted by one employer does not automatically guarantee acceptance by another employer. Hiring standards and available positions may differ.

Receiving Your Results

EEI does not provide test results directly to applicants. Contact the company that administered the test for information about your result and the next stage of its hiring process.

If you previously took an EEI employment test for another company, tell the new employer. The employer will determine whether it can obtain or accept the previous result.

Retaking the MASS Test

EEI does not impose one applicant-facing retesting rule that applies to every company. Waiting periods, retest limits, and score-validity policies are established by the employer administering the selection process.

Contact the employer’s recruiter or testing administrator for the rule that applies to your application.

How Can I Prepare for the MASS Test?

MASS is an aptitude battery rather than a test of detailed power plant maintenance procedures. Preparation should focus on becoming familiar with the question formats and completing each type of problem accurately under strict time limits.

Begin with untimed practice to learn each question type. Once you understand the methods, repeat the exercises under the official section limits.

MASS Study Checklist

  • Practice reading technical passages and locating supporting details quickly.
  • Review gears, pulleys, levers, balance, force, pressure, fluids, motion, and basic machine principles.
  • Practice visualizing how flat or separate pieces fit together.
  • Review fractions, decimals, percentages, ratios, proportions, conversions, and basic formulas.
  • Memorize common arithmetic procedures so you do not waste time deciding how to begin.
  • Complete short timed drills before attempting a full practice battery.
  • Skip a difficult item temporarily when the testing instructions permit it rather than sacrificing an entire section.
  • Review why each missed answer was wrong before repeating the practice set.

Section-Specific Strategies

Reading and Mechanical Concepts

  • Base reading answers on the passage rather than outside knowledge.
  • Identify the mechanical principle before comparing the answer choices.

Objects and Mathematics

  • Compare distinctive edges, angles, and connection points first.
  • Estimate when possible and avoid unnecessary calculation steps.

MASS Study Resources

Top Study Guide:

Best Online Course:

Free Practice Resources:

MASS and Power Plant Maintenance Positions Selection System are test names associated with the Edison Electric Institute. EEI is not involved with or affiliated with Mometrix Media LLC or StudyGuideZone.com, nor does EEI endorse or sponsor any products or services offered by Mometrix Media LLC or StudyGuideZone.com.

 

Last Updated: July 29, 2026