Health and safety¶

Exercise health-and-safety-annex.pdf · PDF

How many hours did you spend in front of a screen yesterday? Add up school, homework, YouTube, games, your phone in bed. For most people your age it is well over six. Now imagine doing that for forty years of work.

And one day soon you will open a computer: swap a RAM stick, change a disk, fix a friend's laptop. A computer looks harmless, but inside there is mains electricity, components that die from a spark you can't even feel, and batteries that can catch fire. Nothing here is dangerous if you know the rules. This page gives you the rules.

Why this is part of a computer course¶

Occupational risk prevention (prevención de riesgos laborales, PRL) is the set of measures that protect workers' health and safety at work.

In Spain it is the law, not a suggestion:

As an IT professional you will face two kinds of risk: the workshop (opening and repairing hardware) and the desk (hours in front of a screen). We take them one at a time.

Electrical risk: protect yourself¶

Inside the power supply, a desktop computer handles mains electricity: 230 V in Spain. That can kill.

The golden rules before opening any computer:

1. Shut it down and unplug it. Switching it off is not enough: many power supplies keep some parts live while the cable is connected.
2. Press the power button once after unplugging, to drain the remaining charge.
3. Never open the power supply (PSU) or a monitor's power board. Inside there are capacitors, components that store electricity like a tiny battery, and they can keep a dangerous charge even after the cable is unplugged. A faulty PSU is replaced, never repaired in class.
4. Dry hands, dry bench. No drinks near an open computer.

flowchart LR
    A["<b>1 · Shut down</b><br>from the OS"] --> B["<b>2 · Unplug</b><br>the power cable"]
    B --> C["<b>3 · Press power</b><br>drain leftover charge"]
    C --> D["<b>4 · Ground yourself</b><br>wrist strap or<br>touch the chassis"]
    D --> E["<b>5 · Open</b><br>the case"]

Electrostatic discharge: protect the computer¶

You walk on a carpet, touch a door handle and — zap. That spark is electrostatic discharge (ESD): static electricity your body builds up, jumping to a metal object.

ESD is the sudden flow of static electricity between two objects with different charges.

Here is the trap: you only feel a discharge from roughly 3,000 volts upwards, but many electronic components can be damaged by less than 100 volts. So you can kill a RAM stick without noticing anything at all. Sometimes the part doesn't die at once: it becomes unreliable and fails weeks later.

How to avoid it:

• Wear an antistatic wrist strap clipped to the computer's metal chassis. It keeps your body at the same charge as the computer, so no spark can jump.
• No strap? Touch the bare metal of the chassis before touching any component, and do it again every time you move around.
• Hold components by the edges. Never touch the gold contacts or the chips.
• Keep new parts in their antistatic bag until the moment you install them. Never put a component on top of the bag: the outside is not protected.
• Avoid working on a carpet, and wear cotton rather than wool or fleece.

Ergonomics: the desk¶

Ergonomics is adapting the workplace to the person, not the person to the workplace.

The desk risk is slow: nothing happens today, but years of bad posture bring back pain, neck pain, wrist pain and tired eyes. RD 488/1997 lists what a screen workstation must have — screen, keyboard, chair and table that can be adjusted to the person.

flowchart TB
    subgraph SCREEN ["Screen"]
        S1["<b>Distance</b><br>at least 40 cm<br>(about an arm's length)"]
        S2["<b>Height</b><br>top edge at or<br>slightly below eye level"]
        S3["<b>Position</b><br>straight in front, sideways<br>to windows: no glare"]
    end
    subgraph BODY ["Your body"]
        B1["<b>Back</b><br>against the backrest"]
        B2["<b>Arms</b><br>forearms resting,<br>wrists straight"]
        B3["<b>Feet</b><br>flat on the floor<br>or on a footrest"]
    end
    SCREEN --- BODY

Eye strain and the 20-20-20 rule¶

Looking at a screen, you blink less and your eyes focus at the same distance for hours. The result is digital eye strain: dry, tired eyes, blurred vision and headaches at the end of the day.

A simple habit helps: the 20-20-20 rule — every 20 minutes, look at something 20 feet away (about 6 metres) for 20 seconds. It was coined around 1991 by the American optometrist Jeffrey Anshel as an easy-to-remember way to get office workers to take breaks. It is a helpful reminder, not magic: real breaks away from the screen matter too.

RD 488/1997 also gives screen workers the right to health checks with attention to their eyes, including an eye exam when needed.

Batteries, weight and cables¶

Lithium batteries¶

Laptops, phones and power banks use lithium-ion batteries. They store a lot of energy in a small space, and when damaged they can overheat and catch fire.

• A swollen battery (a laptop whose case bulges, a phone whose screen lifts) is a warning sign. Stop using and stop charging it.
• Never puncture, bend or crush a battery. Never try to "press it flat".
• Charge on hard surfaces, not on the bed or the sofa, and with the proper charger.
• A damaged battery goes to a battery collection point, never in the bin.

Lifting heavy equipment¶

Servers, big monitors and boxes of equipment are heavy. The Spanish technical guide for RD 487/1997 recommends not lifting more than 25 kg even in ideal conditions, and warns that loads above 3 kg can already cause back injuries if handled badly.

• Bend your knees, not your back. Keep the load close to your body.
• Don't twist while carrying; turn with your feet.
• A rack server is a two-person job.

Cable management¶

A loose cable across the floor is a trip waiting to happen — for you, and for the computer you drag off the table.

• Run cables along walls or under the desk, tied together.
• Don't overload power strips, and never chain one power strip into another.
• A damaged cable is replaced, not taped.

E-waste: the end of a computer's life¶

E-waste, in Spain RAEE (residuos de aparatos eléctricos y electrónicos), is any electrical or electronic device that has been thrown away.

Computers contain toxic materials (lead, mercury, the battery chemicals) and valuable ones (copper, gold, rare metals). In the ordinary bin they pollute; recycled, they are recovered. RD 110/2015 organizes how it is done:

• Take old devices to a punto limpio (the municipal recycling centre).
• When you buy a new device, the shop must take back the equivalent old one for free.
• Shops with at least 400 m² of electronics sales area must take back very small devices (no side longer than 25 cm: phones, chargers, mice...) for free, even if you buy nothing.

Key takeaways¶

• PRL is the law in Spain: Ley 31/1995 in general, RD 488/1997 for screens, RD 487/1997 for lifting, RD 110/2015 for e-waste.
• Before opening a computer: shut down, unplug, drain, ground yourself. Never open a PSU: its capacitors keep charge.
• ESD can damage components at under 100 V — far below the ~3,000 V you can feel. Use a wrist strap or touch the chassis.
• Ergonomics: screen at least 40 cm away, top edge at or below eye level; back supported, wrists straight, feet flat; regular breaks and the 20-20-20 rule.
• A swollen lithium battery is a fire risk: stop using it, don't puncture it, recycle it.
• E-waste (RAEE) goes to a punto limpio or back to the shop, never in the bin — and wipe your data first.

Quick check¶

You now know how a computer is built, how computers connect, and how to handle them safely. Next unit: the software that brings the hardware to life — the operating system.