Module 7: Safety

Everything from this point in the course involves working on real circuits: mains-powered supplies, amplifiers, chargers and batteries. Every one of those skills — building, testing, troubleshooting, repairing — involves real hazards: voltages that can stop a heart, stored energy that remains dangerous long after a switch is turned off, batteries that can burn or explode, ladders and roofs that can kill a careless worker, and chemicals that can damage lungs over years of casual exposure. None of this is meant to frighten you away from electronics. It is meant to give you the specific, accurate knowledge that lets you work confidently and come home safely every single time.

Module Overview

We begin with the fundamentals of electrical shock: why current, driven through body resistance by voltage, is the actual injury mechanism, and exactly how few milliamps separate a harmless tingle from a fatal heart arrhythmia. From there we go straight to the specific equipment that can deliver a lethal shock — valve amplifier power supplies at several hundred volts, microwave oven high-voltage circuits, CRT anode voltages in older televisions and test equipment, and the mains-connected heatsinks found inside many switching power supplies. Capacitor discharge danger gets a lesson of its own, because the energy stored in a large filter capacitor is what injures people who believed the equipment was switched off.

Working at height and lightning protection address the hazards of installing equipment outdoors: ladders and roofs for solar panels, cameras and aerials, clearance from overhead power lines, and the earthing and surge protection that keeps a nearby strike from destroying equipment or worse.

The module closes with the hazards of the materials you handle constantly — battery chemistries from lead-acid to lithium, each with sharply different failure modes and charging requirements, and the chemical hazards of solder fume, flux, and PCB etchants. The final lesson, Safe Working Practices, consolidates every rule from this module into a single practical reference for setting up and running a safe workshop.

Prerequisites

This module draws on Ohm's Law and power from the What Is Electricity module, components and batteries from the Basic Electronic Components module, and meter use from the Test Equipment: Basics module. Later modules on power supplies, construction and troubleshooting refer back to it, since most safety situations arise while building, testing, or repairing equipment. No new electronics theory is introduced here — this module is about how to apply what you have learned without injuring yourself or others.

Tools and Materials

Lessons in this module reference a digital multimeter rated for the voltages being measured, insulated hand tools, an anti-static wrist strap, a properly rated bleed resistor and discharge probe for capacitor work, a sound ladder and fall protection for work at height, and basic ventilation (a fan or fume extractor) for soldering and chemical work. None of this module requires test equipment beyond what earlier modules have already introduced — its requirements are personal protective equipment, good habits and a well-organised bench.

Lessons