Electrician Revision Topics

Safe isolation is the prove–isolate–lock off–prove routine that keeps you alive when working on circuits.

Sparks Basics · C&G 2365 Unit 201

Sit a timed 18th Edition mock exam in your browser.

18th Edition Exam Prep · C&G 2382-26

Revise the C&G 2365 Level 2 diploma the way you'd learn a language: short daily lessons, spaced repetition and practice questions instead of a textbook wall.

Sparks Basics · C&G 2365 Units 201–204

Cable sizing means proving a conductor can carry its design current, survive its installation conditions and still deliver acceptable voltage at the far end.

Installation · C&G 2365 Units 203/305

Earthing gives fault current a path home so protection can trip; bonding keeps the metalwork you can touch at the same potential.

Installation · C&G 2365 Units 203/305

Brown is line, blue is neutral, green-and-yellow is earth — but older installations still carry red and black, and three-phase adds grey to the mix.

Sparks Basics

Ohm's law — voltage equals current times resistance — is the one equation every electrical calculation eventually stands on.

Electrical Science · C&G 2365 Units 202/302

The ring final circuit is a UK signature: one cable leaving the board, looping every socket and returning, so current shares two paths.

Testing & Inspection · C&G 2365 Unit 304

Inspection and testing proves an installation is safe before it's energised — dead tests first, live tests after, results certified in writing.

Testing & Inspection · C&G 2365 Unit 304 / C&G 2391

An RCD trips when current leaks out of a circuit — but Type AC, A, F and B devices differ in which fault currents they can actually see.

Installation · C&G 2365 Unit 203

An IP rating is two digits: the first scores protection against solid objects and fingers, the second against water.

Installation · C&G 2365 Unit 203

Amendment 4:2026 is the newest revision of BS 7671 — and the version current 18th Edition exams are set against.

18th Edition Exam Prep · C&G 2382-26

Three-phase supplies deliver power on three conductors whose voltages peak in turn — smoother power, smaller cables, and a factor of root three everywhere.

Electrical Science · C&G 2365 Unit 302

The consumer unit is where a domestic installation is protected, isolated and explained to whoever comes next.

Installation · C&G 2365 Unit 305

Dead tests come before live ones for a reason: you do not energise an installation you have not proved safe.

Testing & Inspection · C&G 2365 Unit 304 / 2391

R1+R2 is the measured resistance of the line conductor plus the protective conductor of a circuit.

Testing & Inspection · C&G 2365 Unit 304 / 2391

The three-step ring final continuity test is the one that catches a ring wired as two spurs.

Testing & Inspection · C&G 2365 Unit 304 / 2391

Insulation resistance testing asks one question: are the conductors still separated from each other and from earth?

Testing & Inspection · C&G 2365 Unit 304 / 2391

Zs decides whether a protective device disconnects fast enough to keep someone alive.

Testing & Inspection · C&G 2365 Unit 304 / 2391

Prospective fault current is how much current would flow in a dead short.

Testing & Inspection · C&G 2365 Unit 304 / 2391

An RCD that has never been tested is a promise nobody has checked.

Testing & Inspection · C&G 2365 Unit 304 / 2391

C1, C2, C3 and FI decide whether a report reads satisfactory or not.

Testing & Inspection · C&G 2391

Battery storage brings a second source of supply into a house.

18th Edition Exam Prep · C&G 2382-26

Functional earthing makes equipment work; protective earthing keeps people alive.

18th Edition Exam Prep · C&G 2382-26

PoE turns data cabling into a power distribution system, and bundles of it get hot.

18th Edition Exam Prep · C&G 2382-26