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All courses11-part course

Building Electrical Fundamentals

A free 11-lesson course on the electrical system inside a building: switchboards, substations, single line diagrams, breakers, cables, earthing, surge protection, power cuts and control panels, plus what to do when something trips.

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The map

  1. 1

    MSB, SSB and DB: Your Building's Electrical Tree

    MSB, EMSB, SSB, DB: the acronyms on every electrical drawing are just tiers of one tree. See why a building splits its power instead of running one giant board, and trace your kettle back to the transformer.

  2. 2

    Inside the Consumer Substation: The Locked Room

    Every building has a locked room marked DANGER 11,000 V that almost nobody has seen inside. Walk the consumer substation left to right: the ring main unit, the vacuum breaker, the transformer, the meter and the battery that lets the breaker trip when the power fails.

  3. 3

    How to Read a Single Line Diagram

    The boxes-and-one-line drawing on the electrical room wall is a single line diagram. Here is the one trick it is built on, and how to read it top to bottom.

Protection

  1. 4

    Circuit Breaker Types: ACB, MCCB, MCB, RCCB, RCBO

    MCB, MCCB, ACB, RCCB, RCBO, ELCB: not just sizes of one thing. Which breaker types protect the cable, which protect the person, and why the main one is huge.

  2. 5

    Cable Size and Voltage Drop: Why Distance Matters

    A power tool runs weak at the end of a long extension cord, and the cord comes back warm. That warmth is voltage drop, made touchable. Here is why distance changes everything, and how cable sizing answers just two questions: how many amps, and how far.

  3. 6

    Neutral and Earth: Why They Stay Separate (TT and TN-S)

    Neutral and protective earth do different jobs. How they relate in TT and TN-S installations, why an extra link between them is dangerous, and what to ask a competent person to check.

  4. 7

    Lightning and Surge Protection: Why the Router Dies

    The storm passes, the kettle is fine, but the router is dead. Why lightning kills your cleverest electronics and how surge protection really works in Malaysia.

Power cuts

  1. 8

    When the Mains Fails: Generators, ATS and UPS

    When the TNB supply fails, some loads never stop, some stop for a few seconds and some wait for the mains. How the essential switchboard, standby generator, automatic transfer switch and UPS work together, how long backup lasts, and who does what during a power cut.

Equipment control

  1. 9

    Inside an Electrical Control Panel

    The grey door that hums and clunks holds two worlds: a 400 V power circuit that does the work and a 24 V control circuit that decides. Meet the contactor, and the rest of the box reads itself.

  2. 10

    How to Read Control Wiring Diagrams

    The schematic that shows a panel's logic looks like hieroglyphics until you learn its grammar: two supply rails, one decision per rung, NO/NC contacts, device codes and the start-stop seal-in circuit that gives a machine its memory.

Finish

  1. 11

    A Trip Is a Clue: Fault Reporting and Electrical Maintenance

    The final part of Building Electrical Fundamentals is a worked case. A chilled-water pump in our example office tower trips on overload. Read the lamps and the BMS alarms, find the circuit on the SLD, write the fault record and the escalation brief, and see what the competent person checks.