How to Pass the CAST Test

The CAST test is the Construction and Skilled Trades Selection System, a pre-employment aptitude battery published by the Edison Electric Institute (EEI)™ and used by electric utilities across the United States to screen applicants for physically and technically demanding trade roles — lineworkers, electricians, substation operators, and transmission & distribution (T&D) crews. If a utility has asked you to sit the CAST, this guide walks you through all four sections, the timing pressure, the 1–10 index score, and gives you real practice questions with fully worked answers — plus honest, hedged answers on the two things the rest of the internet gets wrong: the passing score and the calculator policy.

Quick note before we start: the “cast test” you are here for is the electric-utility hiring exam, not the California Science Test (also abbreviated CAST). Everything below is about the EEI utility assessment.

What is the CAST test?

The CAST test is a standardized aptitude assessment that predicts how well an applicant is likely to perform in a skilled-trades utility job. It measures four things employers care about: the ability to read measurements off a drawing, mechanical reasoning, reading comprehension, and quick arithmetic. It is not a knowledge test of electrical theory — you do not need to know Ohm’s law or line-work procedures to sit it. It measures the underlying aptitudes a utility believes make someone trainable for those roles.

Who owns and administers it

The CAST is one of a family of selection tests developed and owned by the Edison Electric Institute (EEI), the trade association of U.S. investor-owned electric utilities. EEI licenses the test to member utilities, who administer it (usually through their own HR or a proctored testing center) as a hurdle in the hiring process. Because EEI owns it, the exact content and scoring are confidential, and no third party — including this site — has access to live questions.

What CAST stands for

CAST is short for the Construction and Skilled Trades Selection System. The name tells you the target: hands-on construction and skilled-trades roles rather than plant operations or clerical work (those are covered by EEI’s sibling tests, which we compare later). If your job posting mentions “CAST” or “Construction and Skilled Trades,” you are in the right place.

Which utilities and roles use it

The CAST is the standard screen for line and field trade roles at a large share of U.S. electric utilities. Job titles that commonly require it include:

• Apprentice lineman / lineworker (overhead and underground)
• Electrician and maintenance electrician
• Substation operator and substation technician
• Transmission & distribution (T&D) field crews
• Meter, relay, and general construction trade roles

Utilities frequently associated with EEI-family tests such as the CAST include ComEd, Ameren, PECO, Duke Energy, American Electric Power (AEP), Eversource, and Florida Power & Light (FPL), among many others. Policies change and each utility decides which of its roles require the CAST, so always confirm from your own job posting or recruiter which test and which sections apply to you.

CAST test format: sections, questions, and timing

The CAST has 110 questions across four separately timed sections. You cannot go back to a section once its timer expires, and each section rewards a different skill. Here is how the 110 questions break down.

Graphic Arithmetic — 16 questions, 30 minutes

You read a dimensioned drawing — a shop print or blueprint — and calculate a measurement that is not directly labeled, usually by adding or subtracting the dimensions that are shown. This is the most CAST-specific section: it blends print-reading with arithmetic, and it is where most other prep sites give you text-only algebra and skip the actual drawing-reading skill. We fix that with a real worked example further down.

Mechanical Concepts — 44 questions, 20 minutes

The largest section, at 40% of the test. You are shown a picture of a mechanical situation — gears, levers, pulleys, forces, fluids, simple structures — and choose the correct outcome. No math is required; it tests physical intuition. With 44 questions in 20 minutes, this section is as much about speed as it is about mechanics.

Reading for Comprehension — 32 questions, 30 minutes

Trade-flavored passages — safety notices, work procedures, technical manuals — followed by questions you answer using only the information in the passage. The reading level is workplace, not academic, but the passages are dense and the questions reward careful reading over speed.

Mathematical Usage — 18 questions, 7 minutes

Short, applied arithmetic and formula problems — unit conversions, rates, percentages, simple formula rearrangement. The math itself is not advanced, but 18 questions in 7 minutes is the tightest window on the entire test. This is the section that decides whether you have trained your speed.

How tight is the timing?

The four section timers add up to about 87 minutes of answering time; with instructions and setup, most applicants describe the sitting as roughly 90 minutes. Sources vary slightly on the exact minutes, so treat these as close working figures and confirm with your utility. What every source agrees on is the pattern of pressure — and that is easiest to see as seconds per question:

The contrast is stark: Graphic Arithmetic gives you nearly two minutes per question, but Mathematical Usage gives you barely 23 seconds — and Mechanical Concepts, the biggest section, only about 27. The takeaway is that the CAST is not one uniformly fast test; it is two relaxed sections and two sprints. You pace them completely differently.

How the CAST test is scored: the 1–10 index explained

What the index score actually is (not a percentage)

Your raw answers are converted into an index score on a 1 to 10 scale. This is the single number the utility sees, and it is the most misunderstood part of the whole test. The index is not a percentage and not “how many you got right.” A 7 does not mean you answered 70% correctly. It is a scaled score that places your result on EEI’s validated scale — a higher index reflects a higher predicted probability of successful job performance in the target role.

What score do you need to pass?

There is no single universal passing score, because each utility sets its own cutoff. That said, the widely reported convention — cross-checked across major prep sources — is that most utilities treat an index of about 4 to 5 as the practical minimum, and that competitive roles (and applicant pools where many people clear the bar) effectively require a 6 or higher. Treat those numbers as commonly cited guidance, not a guarantee: your utility may set the line higher or lower, and it may rank everyone above the line by score. The safe target is simple — aim as high as you can rather than aiming to just clear a rumored minimum.

How the index maps to job-performance probability

EEI validated the CAST against actual on-the-job performance, which is why the index is framed as a probability of successful performance rather than a grade. In practical terms, a higher index tells the utility you are statistically more likely to succeed in training and on the job — which is exactly why competitive applicant pools push the effective bar above the bare minimum. It also means there is real value in every point: moving from a 5 to a 7 genuinely changes where you sit in the ranked pool.

Is the CAST test hard?

Content difficulty vs time pressure

Honestly? The content of the CAST is not advanced. There is no calculus, no electrical theory, no specialized trade knowledge — it is arithmetic, print-reading, everyday mechanics, and workplace reading. What makes the CAST hard is speed. The difficulty lives almost entirely in the clock. People who fail rarely fail because a question was beyond them; they fail because they ran out of time or rushed and made careless errors under pressure.

The two toughest sections

Mathematical Usage is the pressure cooker — 18 questions in 7 minutes means roughly 23 seconds each, with no room to double-check. Graphic Arithmetic is tough for a different reason: even though you get almost two minutes per question, reading dimensions off an unfamiliar drawing is a skill most applicants have never practiced, so the time evaporates if you are learning the format live. Practice removes both problems.

What trips first-time takers up

The classic first-timer mistakes: assuming holes or features on a drawing are evenly spaced instead of doing the subtraction; getting stuck on one hard Math Usage item and burning 60 seconds you did not have; and treating the whole test at one pace instead of easing off on the two timed-generous sections and sprinting on the two tight ones. All three are fixable by taking the test in its real format before test day.

CAST test practice questions (with worked answers)

Below are three CAST-style practice questions with fully worked answers — one from each of the sections that trip people up. These are simulated, original questions written to match the CAST’s style and format — they are not actual test content. Reveal each answer only after you have tried it.

WORKED EXAMPLE — GRAPHIC ARITHMETIC (style question, not actual test content)

The drawing shows a steel bracket plate 12 1/2 in. wide, with holes A, B, and C dimensioned along the bottom row. Hole A is 1 1/4 in. from the left edge, A to B is 4 3/4 in. center to center, and hole C is 2 in. from the right edge. What is the center-to-center distance between hole B and hole C?

A. 4 in.   B. 4 1/4 in.   C. 4 3/4 in.   D. 4 1/2 in.   E. None of these

Show the answer & how to get it

Answer: D — 4 1/2 in. The B-to-C gap is not labeled, so close the chain across the full width. The labeled pieces are 1 1/4 in. (left edge to A), 4 3/4 in. (A to B), and 2 in. (C to right edge). Subtract them all from the 12 1/2 in. width: 12 1/2 − 1 1/4 − 4 3/4 − 2 = 4 1/2 in. The lesson: never assume holes are evenly spaced — let the numbers close the chain.

WORKED EXAMPLE — MECHANICAL CONCEPTS (style question, not actual test content)

A straight ramp 12 ft long rises 3 ft from a sidewalk up to a porch. Ignoring friction, about how much force is needed to hold a 400-lb drum on the ramp?

A. About 200 lb   B. About 100 lb   C. About 400 lb

Show the answer & how to get it

Answer: B — about 100 lb. On a frictionless ramp, the holding force equals the load times the rise divided by the ramp length: 400 lb × (3 ft ÷ 12 ft) = 100 lb. The ramp is four times as long as it is tall, so it trades distance for force and cuts the effort to a quarter of the drum’s weight. This is the inclined-plane idea the Mechanical Concepts section tests over and over.

WORKED EXAMPLE — MATHEMATICAL USAGE (style question, not actual test content)

On a bicycle, the pedals turn a 48-tooth chainring connected by a chain to a 16-tooth sprocket on the rear wheel. For each complete turn of the pedals, how many turns does the rear wheel make?

A. 1/3 of a turn   B. 3 turns   C. 1 turn

Show the answer & how to get it

Answer: B — 3 turns. Each pedal revolution feeds 48 chain links past the rear sprocket, and every 16 links turns that sprocket once. So the rear wheel makes 48 ÷ 16 = 3 turns per pedal turn. Under a 23-second clock, the move is to spot the ratio (big drives small → faster) and divide — not to overthink it.

Want more? Work a full set with instant explanations on our free mechanical aptitude test (no email required), or browse more sample questions by topic.

Test-day logistics: calculator, retakes, and what to bring

Can you use a calculator?

Here is the honest answer the rest of the SERP won’t give you straight: historically, no calculator has been allowed on the paper CAST — the Mathematical Usage and Graphic Arithmetic sections are designed to be done by hand, which is exactly why your mental-math speed matters so much. That said, administration details can vary by utility and by testing format, so verify the calculator policy with your utility or recruiter before test day rather than trusting any blanket claim online. The safe move either way: train assuming you get no calculator, so you are never caught out.

Retake policy

If you don’t clear the bar, you generally can retake the CAST — but not immediately. The commonly reported rule is a minimum wait of 30 days between attempts and a cap of 2 attempts within a 12-month period. Because attempts are limited and spaced out, your first sitting genuinely matters — a wasted attempt can push your hiring timeline back months. Confirm the exact policy with your utility, since they administer the retake window.

Paper vs online administration

The CAST has traditionally been a proctored, paper-and-pencil test taken at a utility facility or testing center. Some utilities may offer or move toward online-proctored formats. Because the format affects what you bring (ID, scratch paper allowances) and whether a calculator is even physically possible, your invitation email or recruiter is the source of truth — read it carefully and ask if anything is unclear.

CAST vs the other EEI tests (POSS, MASS, TECH)

Which EEI test am I taking?

EEI publishes a family of selection tests, and confused applicants often prep for the wrong one. The quick rule: the CAST is for construction and skilled-trades roles (lineworkers, electricians, T&D). If your posting names a different test — POSS, MASS, or TECH — you want a different guide. Use the table to self-route.

For the full EEI family and how the batteries overlap, see our Edison Electric Institute exam guide. If you’re heading into utility or union trade hiring more broadly, the electrical aptitude test and IBEW aptitude test guides cover the adjacent screens you may also face.

How to prepare for the CAST test

Because the CAST is a speed test on familiar content, the best preparation builds fluency and pacing — not new knowledge. Work this four-step plan.

Build speed, not just accuracy

Most applicants can get the answers right with unlimited time. The CAST does not give you unlimited time. Practice against a clock from day one so that “fast enough” and “correct” become the same habit — especially in Mathematical Usage and Mechanical Concepts.

Practice the exact section formats and timers

Familiarity kills test-day surprise. Reading dimensions off a print, mapping a mechanical picture to a principle, rearranging a quick formula — each is a format skill that gets faster with reps. Brush up the underlying mechanics too with our gears, levers, and mechanical formulas explainers.

Target your weakest section first

Your index is built from all four sections, so the fastest way to raise it is to lift your worst one. A candidate who is already comfortable with mechanics gains far more from an hour on Graphic Arithmetic prints than another hour on gears they already know.

Frequently asked questions

What is a passing score on the CAST test?

There is no single universal passing score — each utility sets its own cutoff on the 1–10 index. The commonly reported convention is that most utilities treat an index of about 4–5 as the practical minimum, and competitive roles effectively require a 6 or higher. Because the exact line varies and many utilities rank applicants by score, aim as high as you can rather than for a rumored minimum. Confirm the cutoff with your utility.

How many questions are on the CAST test and how long is it?

The CAST has 110 questions across four separately timed sections: Graphic Arithmetic (16 questions / 30 minutes), Mechanical Concepts (44 / 20), Reading for Comprehension (32 / 30), and Mathematical Usage (18 / 7). That is about 87 minutes of answering time, and roughly 90 minutes with instructions. Sources vary slightly on the exact minutes, so treat these as close working figures.

Is the CAST test hard?

The content is not advanced — arithmetic, print-reading, everyday mechanics, and workplace reading, with no electrical theory required. The difficulty is speed. Mathematical Usage (about 23 seconds per question) and Graphic Arithmetic (an unfamiliar drawing-reading format) trip up first-timers most. Practicing in the real format and time limits removes most of the challenge.

Can you use a calculator on the CAST test?

Historically, no calculator has been allowed on the paper CAST — the math sections are meant to be done by hand, which is why mental-math speed matters. Administration details can vary by utility and format, so verify the calculator policy with your utility or recruiter before test day. Either way, the safe approach is to train assuming you will not have one.

How is the CAST test scored, and what does the 1–10 index mean?

Your raw answers are converted into an index score on a 1–10 scale. The index is not a percentage and not the number you got right — it is a scaled score that reflects your predicted probability of successful job performance in the target role. A higher index places you higher in the ranked applicant pool, which is why every point matters.

How many times can you take the CAST test, and how long do you wait to retake it?

The commonly reported policy is a minimum 30-day wait between attempts and a cap of 2 attempts within a 12-month period. Because attempts are limited and spaced out, your first sitting genuinely matters — prepare fully before you take it. Confirm the exact window with your utility, which administers the retake.

CAST™ is a trademark and property of the Edison Electric Institute (EEI), which is not affiliated with and does not endorse this site. All practice material is original and simulated — it does not contain actual test questions. See our full disclaimer.