I Almost Burned My House Down with a Lithium-Ion Battery
The “Spicy Pillow” That Fights Back
I was trying to replace the battery in an old phone. It was glued in tight, so I used a metal pry tool to try and lift it. I was careless. The tool punctured the battery’s thin foil casing. I heard a hiss, saw a puff of smoke, and the battery instantly swelled up and caught fire, shooting jets of flame across my workbench. I managed to smother it with a fire extinguisher, but it was a terrifying lesson. Lithium-ion batteries are bombs waiting to happen. Never use metal tools near them, and always work with extreme caution.
The “One-Hand” Rule: The Trick That Can Save Your Life When Working on High-Voltage Power Supplies
The Path of Least Resistance
When I’m working on a “live” high-voltage circuit, like the inside of an old tube amplifier, I follow the “one-hand rule.” I physically put my left hand in my back pocket. I only use my right hand to hold my multimeter probe or tool. This prevents the possibility of creating a closed circuit across my heart. If I were to accidentally touch a live component with one hand and a ground with the other, the electricity could travel up one arm, across my chest, and down the other, which can be fatal.
How to “Safely Discharge” a TV Capacitor That Can Literally Kill You
The Widowmaker in the Glass Box
The inside of an old CRT television contains a massive capacitor that can hold a lethal electrical charge for days, even after it’s been unplugged. Before I ever work on one, I have to safely discharge it. I take a screwdriver with a well-insulated handle and attach a jumper wire with alligator clips from the metal shaft to the TV’s metal frame (ground). Then, with extreme care, I slide the tip of the screwdriver under the rubber suction cup on the back of the tube until it touches the metal contact. A loud “POP” confirms the charge is safely dissipated.
The “Anti-Static Wrist Strap” Isn’t a Suggestion, It’s a Requirement
The Invisible Killer of Components
A tiny, invisible spark of static electricity from your body can instantly destroy a sensitive microchip. A “part per million” failure rate is unacceptable in manufacturing, so they take extreme precautions. I learned that I must too. Before I touch any modern circuit board, I wear an anti-static wrist strap. It clips to a grounded metal point, like my PC case, and ensures that my body and the device are at the same electrical potential. It’s a two-dollar piece of gear that has saved me from hundreds of dollars in “mysterious” component failures.
Why You Should Never Work on a Device That’s Still Plugged In (Even If It’s “Off”)
The Vampire Power is Real
Even when a device like a TV or a PC is “off,” it’s not truly off. It’s in a standby mode, and certain parts of the power supply circuit are still live, waiting for a signal from the remote or power button. This is called “vampire power.” Working on a device that’s still plugged in, even if it’s turned off, is incredibly dangerous. You could get a nasty shock or short out a component. The first and most important rule of any repair is always the same: unplug it from the wall.
The “Fume Extractor” I Built for $20 to Protect My Lungs from Solder Smoke
The Most Important Health Upgrade
The smoke that comes from soldering is not just melting metal; it’s burning flux, which can release harmful chemicals. Breathing it in all day is a serious health risk. A professional fume extractor is expensive. I built my own for about twenty dollars. I took a standard 120mm computer fan and mounted it inside a small cardboard box. I then attached a flexible dryer vent hose to the back of the box, which I run out a nearby window. This simple DIY setup pulls the harmful smoke away from my face and keeps my lungs safe.
How to Handle a “Punctured” or “Swollen” Li-Po Battery Without Causing a Fire
Dealing with the “Spicy Pillow”
If I see a lithium-polymer battery that is swollen or “puffy,” I treat it with extreme respect. It’s a sign that the internal chemistry has failed and it’s full of flammable gas. I immediately stop the repair. I don’t try to charge it or use it. I carefully place it in a fireproof container, like a metal bucket with sand, and take it outdoors, away from anything flammable. I then take it directly to a designated battery recycling center. A swollen battery is a ticking time bomb, and the only safe move is to get it out of your house.
The “Safety Glasses” That Saved My Eyes from a Shattering Screen
The Five-Dollar Tool That’s Priceless
I was prying a tightly-glued, cracked phone screen off a device. I was applying a bit too much force, and a piece of the glass suddenly broke off and shot directly at my face. It hit the lens of my five-dollar safety glasses with a loud “tick” and fell harmlessly to the bench. My heart stopped. That tiny, sharp shard of glass would have hit my eyeball. I have never, ever worked on a device since that day without wearing my safety glasses. Your eyesight is irreplaceable.
The “Isolation Transformer”: The #1 Safety Tool for Working on Live AC Circuits
The Floating Ground
When you’re working on a device that plugs into the wall, touching any part of the “live” circuit while also touching a grounded object can be fatal. The “isolation transformer” is a critical safety device that electrically isolates the device you’re working on from the earth ground of your house’s wiring. This means you can safely probe the live circuit without the risk of creating a deadly path to ground through your body. It’s an essential, non-negotiable tool for any professional who works on mains-powered electronics.
How to Use a “GFCI” Outlet to Protect Yourself from Electric Shock
The Circuit That Senses a Leak
My workbench power strip is plugged into a “Ground Fault Circuit Interrupter” (GFCI) outlet, the kind with the “Test” and “Reset” buttons you see in bathrooms. A GFCI constantly monitors the amount of current going out and coming back. If it detects even a tiny imbalance—meaning some of the electricity is “leaking” out and going somewhere it shouldn’t, like through your body—it will instantly cut the power in a fraction of a second. It’s an incredibly sensitive safety feature that can protect you from a potentially fatal shock.
The “Right” and “Wrong” Way to Use a Can of Compressed Air
It’s Not Air, and It’s Not a Toy
A can of “compressed air” doesn’t actually contain air; it contains a liquid propellant. The wrong way to use it is to shake the can or spray it at an angle, which can eject the super-cold liquid and damage sensitive components. The right way is to hold the can upright and use short, controlled bursts. Also, never spray it on a running fan to “see it spin fast.” This can generate a voltage and damage the motherboard. It’s a cleaning tool, not a toy.
How to Clean Up a “Mercury” Spill from a Broken LCD Backlight
The Toxic Tube
The backlight in many older LCD monitors is a thin fluorescent tube that contains a small amount of toxic mercury vapor. If you accidentally break one of these tubes during a repair, you need to handle it safely. Don’t use a vacuum cleaner, as it will just vaporize the mercury. You should ventilate the room, carefully sweep up the glass fragments, and use a piece of tape to pick up the fine dust. The broken parts need to be sealed in a plastic bag and taken to a hazardous waste disposal facility.
The “Fireproof” Bag (Li-Po Bag) You Should Be Storing All Your Batteries In
Containing the Fire
I have a large collection of salvaged lithium-ion and Li-Po batteries from old laptops and phones. I store all of them in a special “Li-Po safety bag.” These bags are made from a woven, fire-resistant material, similar to a firefighter’s jacket. If one of the batteries were to spontaneously fail and catch fire, the bag is designed to contain the flames and prevent it from spreading to the rest of my workshop. It’s a cheap and essential piece of safety equipment for anyone who hoards batteries.
Why You Should Never Wear “Jewelry” While Working on Electronics
The Conductive Loop
Before I start any repair, I take off my wedding ring and my metal watch. A metal ring or watch band is a highly conductive loop. If you’re working on a live circuit, and your ring accidentally bridges two points, it can create a dead short, causing a massive amount of current to flow through the ring. This can cause a severe burn and can even weld the ring to the components. It’s a simple safety precaution that prevents a very painful accident.
The “Lock-Out, Tag-Out” Procedure for a Home Workshop
The Un-Pluggable Plug
In industrial settings, there’s a safety procedure called “lock-out, tag-out.” Before working on a machine, a worker puts a physical lock on the plug so no one can accidentally power it on. I use a simple version in my own workshop. If I’m doing a dangerous repair and have to leave it overnight, I will not only unplug the device, but I will put a piece of brightly colored tape over the end of the plug with a note that says “DANGER – DO NOT PLUG IN.” It’s a clear, physical warning to myself and others.
How to Identify “Asbestos” in Very Old Vintage Electronics
The Hidden Hazard in a Hair Dryer
I was restoring a very old, vintage hair dryer from the 1950s. I noticed a fuzzy, white, paper-like material used as a heat shield inside. This was a major red flag. In many old, heat-producing appliances from that era, this material is asbestos. Inhaling asbestos fibers can cause serious lung disease. I immediately stopped the repair, sealed the device in a plastic bag, and took it to a hazardous waste facility. When working with very old vintage gear, you have to be aware of these hidden dangers.
The “Fire Extinguisher” You Need for Your Workbench (And It’s Not a Water-Based One)
The Right Tool for an Electrical Fire
Every workshop needs a fire extinguisher within arm’s reach. But it has to be the right type. A water-based extinguisher is the worst thing you could use on an electrical fire, as water conducts electricity and can make the situation much worse. For an electronics bench, you need at a minimum an “ABC” rated dry chemical extinguisher. The ideal choice is a “Class C” or a clean agent “Halon” extinguisher, which will put out the fire without leaving a damaging residue on your other equipment.
How to Create a “Safe Zone” for a Potentially Explosive Battery
The Metal Bucket of Safety
When I’m testing or charging a lithium battery of unknown origin or condition, I do it in a “safe zone.” I place the battery inside a heavy metal bucket filled with sand, and I do the testing outdoors on a concrete surface, far away from anything flammable. This way, if the battery does have a catastrophic “thermal runaway” event and explodes or catches fire, the sand will absorb the heat and the metal bucket will contain the fire, preventing it from spreading.
The “Dangers” of Lead Solder and How to Minimize Your Exposure
The Heavy Metal Problem
Traditional solder contains lead, a toxic heavy metal. While the risk from just touching it is low, the main danger comes from inhaling the fumes or ingesting lead dust. To stay safe, I always work in a well-ventilated area with a fume extractor. I wash my hands thoroughly after soldering, and I never eat or drink at my workbench. These simple hygiene practices dramatically reduce the risk of lead exposure and allow me to work safely with this useful but hazardous material.
Why You Should Never “Probe” a Live Power Supply with a Cheap Multimeter
The Wrong Tool for a High-Energy Circuit
A cheap, five-dollar multimeter is fine for testing batteries. It is not safe for probing a live, high-voltage power supply. These cheap meters often lack the proper internal fuse protection and input filtering. If you accidentally slip and short something out, a massive amount of current can travel back through the probes and cause the meter itself to explode in your hand. For working on live AC circuits, you need a high-quality, properly CAT-rated multimeter from a reputable brand.
The “First Aid” Kit Specifically for Electronics Repair (Burns, Cuts, Shocks)
The Fixer’s Field Hospital
My general first aid kit is fine, but I have a special, small one on my workbench just for repair-related injuries. It contains burn cream for soldering iron accidents, a variety of bandages for cuts from sharp metal edges, and a good pair of tweezers for removing tiny glass or metal splinters. It also has a card with emergency contact numbers and basic instructions for responding to an electric shock. Being prepared for the specific injuries of your hobby is a mark of a true professional.
How to Lift a “Heavy” Old CRT Monitor Without Breaking Your Back
The Analog Anchor
Old CRT monitors are incredibly heavy and awkward. The weight is all in the front, in the thick glass tube. The wrong way to lift one is by yourself, bending at the waist. The right way is to treat it like a heavy piece of furniture. Get help from a friend. Bend at your knees, not your back. Get a firm grip on the bottom corners of the case. Lift with your legs, keeping your back straight. These amazing old displays are not worth a slipped disc.
The “Sharp Edges” Inside a Computer Case and How to Avoid Them
The Metal Paper Cuts
The inside of a cheap, stamped-metal computer case is a landscape of razor-sharp edges. I have cut my hands more times on a cheap PC case than on any other tool. When working inside a case, I move slowly and deliberately. I am always aware of where the sharp edges are. For intensive jobs, I’ll even wear a pair of thin, cut-resistant work gloves. A little bit of caution can save you from the dozens of “metal paper cuts” that are a frustrating rite of passage for many new PC builders.
Why a “Clean” Workspace is a “Safe” Workspace
The Order That Prevents Accidents
A cluttered workbench is a dangerous workbench. A stray piece of metal can cause a short circuit. A misplaced tool can be knocked onto the floor. A can of solvent can be accidentally ignited by a hot soldering iron. Before I start any repair, I take two minutes to completely clear and clean my workspace. A clean, organized bench not only makes the job easier and more efficient, but it also dramatically reduces the risk of a stupid, preventable, and potentially dangerous accident.
The “Trip Hazard” of Cables and How to Manage Them Safely
The Serpent in the Workshop
The floor of my workshop used to be a snake pit of power cords, extension cables, and test leads. It was a major trip hazard. One day, I almost took a nasty fall after getting my foot caught. I spent the next afternoon installing a proper cable management system. I used wall-mounted power strips, cable trays, and zip ties to get every single cable off the floor and routed neatly along the walls and the back of my bench. A tidy floor is a safe floor.
How to Know When a “Repair” is Too Dangerous and You Should Walk Away
The Gut Feeling of Danger
I was asked to repair a very old, damaged piece of high-voltage industrial equipment. As I looked at the frayed wiring, the cracked insulators, and the questionable previous repairs, I got a bad feeling in the pit of my stomach. This was beyond my skill level and outside my safety knowledge. I politely told the owner that I was not qualified to work on the device safely. Knowing your own limits and having the wisdom to walk away from a dangerous repair is one of the most important safety skills you can have.
The “Hidden” Capacitors on a Microwave That Can Hold a Deadly Charge
The Kitchen’s Most Dangerous Appliance
A microwave oven is the most dangerous common appliance to repair. Even when unplugged, its large, high-voltage capacitor can hold a deadly electrical charge. This capacitor is not always obvious and can look like a simple metal can. Before ever touching the internals of a microwave, even one that has been unplugged for days, you must find this capacitor and safely discharge it by shorting its terminals to the metal case with a well-insulated screwdriver. Failure to do so can be fatal.
How to Safely Dispose of “Hazardous” E-Waste and Chemicals
The Responsible Recycler
As a repairer, I generate hazardous waste: old leaded solder, used cleaning solvents, leaking batteries, and broken fluorescent tubes containing mercury. I never just throw these things in the trash. I have a dedicated, labeled container in my workshop for hazardous materials. Once every few months, I take this container to my local county’s hazardous waste collection facility. They have the resources to dispose of these materials safely and responsibly. It’s a critical part of being an ethical and environmentally conscious technician.
The “Ventilation” You Need for Working with Solvents like Acetone
Don’t Breathe the Fumes
When I’m working with strong chemical solvents like acetone or adhesive removers, I always ensure I have proper ventilation. These chemicals release volatile organic compounds (VOCs) that can be harmful to breathe in. At a minimum, I will open a window and have a small fan blowing the fumes away from my face and towards the outside. For more intensive work, I will wear a respirator mask with organic vapor cartridges. Protecting your lungs is just as important as protecting your eyes.
Why You Should Never Trust a “Circuit Diagram” to Be 100% Accurate
The Lies of the Schematic
A circuit diagram, or schematic, is a crucial tool, but I never trust it completely. I have found countless errors in both official service manuals and community-drawn schematics. The manufacturer might have made a running change on the production line that isn’t reflected in the diagram. So, while I use the schematic as a guide, I always verify the actual connections on the board itself with my multimeter before I make any assumptions. The board is the truth; the schematic is just a theory.
The “Tingling” Sensation That Means You Need to Stop Immediately
The Gentle Warning of a Serious Problem
If you ever touch a metal part of an electronic device and feel a slight “tingling” or vibrating sensation, stop and unplug it immediately. This is a sign that the device’s chassis is not properly grounded and has become “live” with a small amount of AC voltage. While this small current may not be enough to give you a major shock, it is a serious warning sign of a potentially dangerous fault in the power supply or wiring. It’s a problem that must be diagnosed and fixed.
How to Protect Your “Hearing” from Loud Fans or Popping Sounds
The Unseen Damage
As a repair tech, I’m exposed to a lot of sudden, loud noises. The “pop” of a discharging capacitor, the high-pitched whine of a failing component, or just the constant drone of loud cooling fans. Over time, this can damage your hearing. When I’m working on a particularly noisy device or doing a dangerous power-on test, I’ll wear a pair of simple foam earplugs or industrial earmuffs. It’s a simple precaution to protect one of my most valuable diagnostic tools: my own sense of hearing.
The “Alligator Clip” Grounding Technique for Your Soldering Iron
The Path of Least Resistance for Static
To protect sensitive components from static damage during soldering, it’s not enough to just wear a wrist strap. Your soldering iron itself can build up a static charge. My soldering station has a grounding jack. I run a wire with an alligator clip from this jack to the metal chassis of the device I’m working on. This ensures that my soldering iron, my body, and the device are all at the same electrical potential, providing the highest level of protection against electrostatic discharge (ESD).
Why You Shouldn’t “Bake” Circuit Boards in an Oven You Use for Food
The Toxic Kitchen
The internet is full of “hacks” that involve baking a circuit board in an oven to “reflow” the solder. Even if this works, it’s a terrible idea to do it in the same oven you use to cook your food. Circuit boards contain lead, flame retardants, and a host of other chemicals. When you heat the board, these chemicals can release toxic fumes and leave a residue on the inside of your oven. I have a cheap, used toaster oven in my workshop that is dedicated solely for these kinds of questionable, last-resort repair attempts.
The “Thermal” Gloves for Handling Hot Components
The Cool Touch
When I’m using my hot air station to remove a component from a circuit board, the board and the surrounding chips can get incredibly hot. To handle the board safely without waiting for it to cool down completely, I use a pair of heat-resistant thermal gloves, the kind used by mechanics or welders. These gloves allow me to pick up and manipulate a hot circuit board without burning my fingers, which speeds up my workflow and prevents a painful injury.
How to Safely “Test” a Repair Before It’s Fully Assembled
The Smoke Test
After I’ve done a major repair on a power supply or a motherboard, the first power-on is a tense moment. I call it the “smoke test.” I never fully reassemble the device for this first test. I place the circuit board on a non-conductive surface on my bench, connect the bare minimum (power and a power switch), and stand back. I plug it in and power it on for just a second, ready to kill the power instantly if I see any smoke or sparks. This initial, cautious test prevents a potential failure from damaging other components.
The “What’s That Smell?” Guide to Dangerous Electrical Odors
The Nose Knows Danger
Your sense of smell is a powerful diagnostic and safety tool. A hot, dusty smell might just mean your PC needs cleaning. But a sharp, acrid, “ozone” smell often indicates a high-voltage arc or a failing transformer. A “burning fish” smell is the classic scent of an overheating, failing electrical component, like a capacitor or a resistor. If you smell any of these, unplug the device immediately. Your nose can often warn you of a critical failure long before you see any smoke.
How to Explain “Workshop Safety” to a Kid or a Beginner
The Two Golden Rules
When I’m teaching my nephew about electronics, I start with two unbreakable rules. Rule #1: Electricity is lazy and wants to get to the ground as fast as possible. Our job is to never let our body be that path. This is why we unplug things. Rule #2: Hot things are hot. A soldering iron is not a toy, and it will burn you instantly. By simplifying safety down to these two core concepts—respecting the path of electricity and the heat of the tools—I can create a safe foundation for a lifetime of learning.
The “Emergency Plan” for a Workbench Fire
The Rehearsal for a Real Disaster
Every workshop should have a fire plan. Mine is simple. My ABC fire extinguisher is mounted on the wall, within arm’s reach of my bench. My first action is to kill the power to my entire workbench via a single, large emergency shut-off button. My second action is to use the extinguisher. And my third action is to get out and call for help. I have mentally rehearsed this sequence so that if the worst happens, I will react calmly and correctly instead of panicking.
Why You Should Never “Look Down the Barrel” of a Compressed Air Can
The High-Speed Dust Projectile
When you’re using compressed air to clean out a dusty computer case, it’s tempting to get a close look at what you’re doing. But you should never point the straw towards your face or look directly at the area you’re spraying. The high-pressure air can dislodge a small piece of debris or a metal shaving and turn it into a high-speed projectile, aimed directly at your eye. Always wear safety glasses and direct the spray away from your body.
The “Hidden Dangers” of Shattered Glass and Fiberglass from PCBs
The Microscopic Menaces
After a phone screen shatters, the repair area will be covered in microscopic glass shards that can get into your skin and are impossible to see. Similarly, if you have to cut or drill a fiberglass circuit board (PCB), it releases tiny, sharp glass fibers into the air that can be harmful to inhale. After any repair that involves shattered glass or cut PCBs, I meticulously clean my entire workbench with a damp cloth and a vacuum, and I always wear gloves and a dust mask during the work itself.
How to Avoid “Inhaling” Dust from Old, Dirty Electronics
The Decades of Dust
When I open up a vintage piece of electronics for the first time, it’s often filled with decades of accumulated dust, pet hair, and other grime. This dust can contain mold spores, insect parts, and other allergens. Before I do anything else, I take the device outside and use a can of compressed air and a soft brush to do a thorough initial cleaning. This prevents that cloud of old, potentially hazardous dust from being released into my indoor workshop environment.
The “Current Limiting” Power Supply That Can Prevent Catastrophic Shorts
The Safety Net for Your Circuits
A standard power supply will try to provide as much current as it can, which can cause a small short circuit to become a fiery disaster. A “current-limiting” benchtop power supply is a much safer tool. I can set the power supply to a maximum current, for example, 100 milliamps. Now, if I’m testing a circuit and I have accidentally created a short, the power supply won’t surge. It will simply provide the maximum 100mA and light up a warning indicator, protecting both my circuit and myself from a catastrophic failure.
Why You Should Always “Assume it’s Live” Until You’ve Proven Otherwise
The Electrician’s Mantra
This is the single most important safety rule in electronics. Before I touch any part of a circuit, I assume it is live and dangerous. I then use my multimeter, a tool I trust, to prove that it is dead. I will physically test the voltage between the point I’m about to touch and a known ground. Only after my meter reads zero volts do I consider it safe to handle. This simple, disciplined process of “assume, then prove” is the foundation of all safe electrical work.
The “Respect” You Must Have for Electricity, No Matter How Small the Device
Even a AA Battery Can Be a Hazard
It’s easy to get complacent when working with low-voltage DC electronics. But even a simple AA battery can be dangerous under the right circumstances. If you accidentally short it out with a metal tool, it can get incredibly hot and leak corrosive chemicals. A lithium-ion battery can be a fire hazard. Electricity, in all its forms, is a powerful force. Respecting that power, even in the smallest of devices, is the mindset that keeps you safe in the workshop.
How to handle a device that has been soaked in liquid
The Race Against Corrosion
When a device is soaked, the immediate enemy isn’t the water; it’s the electricity. The first step is to immediately remove all power sources—unplug it and take out the battery if possible. Don’t turn it on to “see if it works.” The second step is to displace the water. I open the device and flush the entire circuit board with 99% isopropyl alcohol, which drives out the water and then evaporates cleanly. Only after a thorough drying period do I even attempt to power it on.
The risks of using a cheap, uncertified power adapter
The Fire in the Wall
A cheap, no-name phone charger from a gas station might seem like a bargain, but it’s a huge safety risk. These chargers often lack the proper insulation, filtering, and safety circuits of a certified one. They can fail catastrophically, sending high voltage directly into your expensive phone, destroying it. In a worst-case scenario, they can overheat and cause a house fire. I only use power adapters that are from reputable brands and have the “UL” or “CE” safety certification marks on them.
Why you should never defeat a safety feature like a fuse
The Guardian You Bypassed
A fuse is not a mistake; it’s a deliberate, critical safety component. It is designed to be the weakest link in the chain. When a fuse blows, it’s a symptom of a deeper problem, like a short circuit. If you “fix” the problem by bypassing the fuse with a wire or wrapping it in foil, you have removed that protection. The next time there is a power surge, instead of the 50-cent fuse blowing, the entire, expensive circuit board will fry itself, potentially causing a fire.
How to identify counterfeit components that pose a safety risk
The Fake Part, The Real Danger
I once bought a set of cheap power transistors online. They were counterfeit. When I put them under load, they exploded. Counterfeit components are a major safety risk. To spot them, I look for subtle clues. The printing on the chip might be a slightly different font or color. The physical package might have rougher edges or a different texture than a genuine part. I always buy critical safety components, like power transistors or safety capacitors, from reputable, authorized distributors, never from a random third-party seller.
The “Safety Briefing” I Give Myself Before Every Single Repair
The Pre-Flight Checklist for My Hands
Before I start any repair, I take 30 seconds to give myself a mental safety briefing. What voltages am I dealing with? Have I unplugged the device? Am I wearing my safety glasses? Where is the nearest fire extinguisher? Do I have a plan for how to handle the battery safely? This simple, disciplined, pre-repair checklist forces me to slow down, consider the potential hazards, and consciously put safety first before I ever pick up a tool.