Safety: electrical, electrostatic and physical, and the rules that do not bend

Why this matters

Safety appears in both A+ exams, and it is not a formality in either. The hazards in this trade are genuine: mains voltage kills, stored charge in a power supply kills after it is unplugged, lithium cells burn, and the injury most technicians actually suffer is to their back, lifting something they should have asked for help with.

The exam asks about specific controls and specific procedures because they are specific. This lesson states them once, plainly, as the rules this course assumes — and it restates the electrical ones deliberately, because a candidate taking only this exam will not have met them elsewhere.

The lesson

Mains and stored charge: the equipment you do not open, restated for this exam

The rules about voltage are short and they do not bend.

You do not open a power supply. The capacitors inside hold a lethal charge after it is unplugged, sometimes for a long time. There is nothing user-serviceable inside, a replacement costs less than an hour's labour, and this is the single most dangerous component in ordinary computing equipment. Test a supply at its output connectors, from outside the case.

The same warning applies to:

• Cathode ray displays, which hold very high voltages in the tube and can do so long after disconnection.
• Laser printer power supplies and the high-voltage section of the print engine, which appear in this certification's scope.
• Uninterruptible power supplies, which contain charged batteries and cannot be made safe by unplugging them — by design, that is the whole point of the device.

The general rules:

• Disconnect before opening anything, and on a laptop that includes the internal battery.
• One hand behind your back when working near anything energised, so a current path cannot cross your chest. This sounds theatrical and is standard practice.
• Never work on mains wiring unless you are qualified and permitted to. Replacing a fuse in a plug is not the same as touching a distribution board.
• Wet conditions and mains do not mix, including a damp floor or a spilled drink.

If a piece of equipment feels wrong — buzzing, smelling hot, visibly damaged cabling — the correct action is to isolate it and stop, not to investigate it energised.

Electrostatic discharge, straps, mats, packaging, and the one place a strap is wrong

Electrostatic discharge damages components at voltages far below what a person can feel, which is what makes it insidious: the failure often arrives weeks later, so nobody connects it to the day the part was handled.

The controls, in order of value:

• An anti-static wrist strap, connected to an unpainted metal point on the chassis or to a proper ground. This equalises you with the equipment, which is the actual goal.
• An anti-static mat under the work, bonded to the same point.
• Anti-static bags for storing and transporting components. Note that the protection is on the outside of the bag — placing a board on top of a bag provides nothing.
• Handling boards by their edges, never by the contacts or the chips.
• Touching the chassis before reaching in, which is the free version of the wrist strap and is better than nothing when no strap is available.
• Humidity and flooring. Dry air and carpet generate charge; a workshop at sensible humidity with a hard floor generates much less.

The one place a strap is wrong: never wear a grounded wrist strap while working on or near a power supply, a display tube, or anything else holding mains-level charge. The strap's purpose is to connect you to ground, which is exactly what you must not be when there is a path to high voltage. That exception is examinable and it is also the one that matters.

And the anti-pattern: a strap with no connection, worn as a habit, provides nothing. Clip it to something.

Fire safety: extinguisher classes, and what to do before reaching for one

Fire safety in this trade is mostly about electrical fires and lithium cells, and the classification is worth knowing because using the wrong extinguisher makes things worse.

The classes (naming varies by region; the principle does not):

• Ordinary combustibles — paper, wood, fabric. Water is appropriate.
• Flammable liquids — foam, dry powder or carbon dioxide.
• Electrical fires — carbon dioxide or dry powder. Never water. Water conducts, and the person holding the extinguisher becomes part of the circuit. This is the one to be certain of.
• Metal fires, which require a specialist agent.

Lithium cells deserve their own paragraph. A swollen, punctured or overheating cell can enter thermal runaway, which produces its own oxygen and burns fiercely. Do not puncture, compress, or attempt to charge a damaged pack. Move it away from anything flammable if it is safe to do so, and use a suitable agent or copious water for a small cell fire — the advice differs from electrical fires because the hazard is chemical rather than electrical once it is burning.

What to do before reaching for an extinguisher:

1. Raise the alarm. Other people matter more than equipment.
2. Cut the power if it is safe and quick — at the wall, or at the distribution board.
3. Evacuate if the fire is not small, not contained, or between you and the exit.
4. Only then, if it is small, contained, you have the right extinguisher, and you have a clear route out, consider tackling it.

Nothing in a server room is worth a person, and an extinguisher used on a fire that is already beyond it costs the seconds that mattered.

Lifting, carrying and the two things on this exam that regularly injure people

The injuries technicians actually suffer are mostly to backs, and they come from equipment that does not look heavy enough to be dangerous.

The technique, which is genuinely examinable:

• Assess the load first. Weight, shape, how far it is going, and whether you can see over it.
• Get close to it. Reaching out multiplies the load on your spine.
• Bend your knees, keep your back straight, and lift with your legs.
• Do not twist while carrying. Turn with your feet.
• Keep it close to your body.
• Set it down the same way.
• Plan the route before you pick it up, and clear it.

Ask for help, or use equipment. A trolley for anything heavy or awkward, and two people for anything you would hesitate over. There is usually a stated weight limit in the organisation's guidance, and it is a limit rather than a target.

The two things on this exam that regularly injure people:

• Printers, particularly office multifunction devices, which are much heavier than they look, have no good handholds, and are usually in an awkward position under a desk or against a wall.
• Display equipment, particularly older tube displays, which are heavy, front-weighted, and awkward to hold.

Server equipment belongs on the list too: a rack-mounted server is front-heavy, and fitting one at head height alone is how people are hurt.

The habit worth building is the pause before lifting: is this heavier than it looks, can I see where I am going, and is there anyone to help? Three seconds, and it is the difference between a routine job and six weeks off.

Personal safety at a customer site, including when to stop work

Working on someone else's premises adds hazards that are not in any equipment manual.

Before starting:

• Sign in and follow the site's rules. There may be a safety induction and it is not optional.
• Know the fire exits and the assembly point.
• Ask about hazards — restricted areas, live equipment, machinery, anything requiring protective equipment.
• Ask about permits. Some sites require a permit for work near electrical systems or at height.

While working:

• Do not create hazards. Trailing cables across a walkway, a raised floor tile left open, a case left with sharp edges exposed, a chair used as a ladder. Cable across a doorway is the classic and it is how someone else gets hurt by your work.
• Use the right access equipment. A step ladder, not a desk.
• Be aware of other people, particularly in homes with children and pets, and in workplaces where others are concentrating.

When to stop work. This is the part worth stating explicitly, because the pressure is always in the other direction:

• The equipment is damaged in a way that makes it unsafe — scorching, exposed conductors, a smell of burning.
• You are being asked to do something outside your competence or your permissions.
• The environment is unsafe — water, an unstable structure, inadequate light.
• You are too tired to be doing electrical work safely.
• Someone on site is behaving in a way that makes you unsafe.

Stopping is a legitimate professional decision. Explain why, put it in writing, and escalate. Nobody has ever been thanked for finishing a job that ended in an ambulance.