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Electrical Topics, Explained Simply

Pick anything you’re curious about. Each page explains it in plain English and answers common questions. Explore key terms on every topic page without an account. Where answer checking is available, the sample is labelled interactive. Course labels below describe full learning-path access; every guide is free to read.

Safe Isolation Procedure

Safe isolation is the habit that keeps you alive before you touch a circuit: switch it off, lock it off, then prove it is dead.

Free interactive sample · Sparks Basics · C&G 2365 Unit 201

18th Edition Mock Exam

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

Free interactive sample · The Regs and Practice Papers · C&G 2382-26

C&G 2365 Level 2

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

Free interactive sample · Sparks Basics · C&G 2365 Units 201–204

Cable Sizing

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

Free interactive sample · Installation · C&G 2365 Units 203/305

Earthing & Bonding

Earthing gives a fault a safe path home so the protection trips.

Free guide + key terms · Installation · C&G 2365 Units 203/305

UK Cable Colours

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.

Free guide + key terms · Sparks Basics

Ohm's Law

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

Free interactive sample · Electrical Science · C&G 2365 Units 202/302

Ring Final Circuits

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

Free guide + key terms · Testing & Inspection · C&G 2365 Unit 304

Inspection & Testing

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

Free interactive sample · Testing & Inspection · C&G 2365 Unit 304 / C&G 2391

RCD Types

An RCD is a safety switch that trips when current leaks out of a circuit.

Free guide + key terms · Installation · C&G 2365 Unit 203

IP Ratings

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

Free guide + key terms · Installation · C&G 2365 Unit 203

BS 7671 Amendment 4

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

Free interactive sample · The Regs and Practice Papers · C&G 2382-26

Three-Phase Power

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

Free guide + key terms · Electrical Science · C&G 2365 Unit 302

Consumer Units

The consumer unit — the fuse board — is where a home's supply splits into circuits, each with its own protection.

Free guide + key terms · Installation · C&G 2365 Unit 305

Dead Testing Sequence

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

Free interactive sample · Testing & Inspection · C&G 2365 Unit 304 / 2391

R1+R2 Continuity Testing

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

Free guide + key terms · Testing & Inspection · C&G 2365 Unit 304 / 2391

Ring Final Circuit Testing

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

Free guide + key terms · Testing & Inspection · C&G 2365 Unit 304 / 2391

Insulation Resistance Testing

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

Free interactive sample · Testing & Inspection · C&G 2365 Unit 304 / 2391

Earth Fault Loop Impedance (Zs)

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

Free interactive sample · Testing & Inspection · C&G 2365 Unit 304 / 2391

Prospective Fault Current

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

Free guide + key terms · Testing & Inspection · C&G 2365 Unit 304 / 2391

RCD Testing

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

Free guide + key terms · Testing & Inspection · C&G 2365 Unit 304 / 2391

EICR Codes C1, C2 and C3

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

Free guide + key terms · Testing & Inspection · C&G 2391

Battery Energy Storage Systems

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

Free interactive sample · The Regs and Practice Papers · C&G 2382-26

ICT Functional Earthing

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

Free guide + key terms · The Regs and Practice Papers · C&G 2382-26

Power over Ethernet (PoE)

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

Free guide + key terms · The Regs and Practice Papers · C&G 2382-26

Electrical Topics, Explained Simply | TradeTraining