Safety and Handling

Electrostatic discharge

Electrostatic discharge (ESD) is the sudden flow of electricity between two objects with a different electrical charge, such as your finger and a memory module. Walking across a carpet or taking off a sweater builds up a static charge on your body; the moment you touch something at a different potential, it equalizes in a tiny spark.

People only feel a discharge from roughly 3,000 volts upward. The microscopic structures inside chips can be damaged by far smaller discharges — a few hundred volts or less for sensitive parts — so you can destroy a component without feeling, seeing or hearing anything.

Why the damage is often invisible

ESD damage comes in two forms. Catastrophic damage kills a component at once: the new memory module simply does not work. Latent damage is worse: the component is weakened but keeps working, and then fails days or weeks later, or causes random errors in the meantime. By then nobody connects the failure to the moment it was handled carelessly, and a technician may spend hours hunting an "intermittent" problem.

Humidity

Dry air lets static charge build up; moisture in the air lets it leak away. That is why static shocks are more common in winter, when heated indoor air is dry. Server rooms and workshops are therefore kept at moderate humidity. Too humid is not good either: it leads to condensation and corrosion.

Preventing ESD

The principle is simple: make sure you, the work surface and the component are at the same electrical potential before and while you touch anything, so no discharge can happen.

• An antistatic wrist strap is a conductive band worn on the skin of the wrist, connected by a cord to a ground point — the bare metal of the computer's chassis or the grounding point of an antistatic mat. It continuously drains any charge you build up. The cord contains a resistor of about 1 megohm, so the charge drains slowly. The resistor limits current as a precaution, but a wrist strap is no protection against mains voltage — never work on live equipment.
• An antistatic mat on the workbench gives the computer and loose components a surface at the same potential as you.
• Antistatic bags: keep components in the shielding bag they came in until you install them, and put removed parts back into one. Ordinary plastic bags and foam generate static.
• Handle parts by their edges: hold memory modules and cards by the edges or the metal bracket, never by the contacts or chips.
• Touch bare metal of the case before touching anything inside, and again if you have walked away. It is a fallback without a wrist strap, not a replacement for it: it only equalizes your charge at that moment.

Grounding

Grounding means connecting objects to the earth, or to a common reference point, so that electrical charge has a safe path to flow away. It serves two purposes in IT work. For ESD, it keeps you, the mat and the equipment at one potential. For electrical safety, the ground pin of a power plug connects the metal case of a device to earth, so that if a live wire touches the case, the current flows away and trips the breaker instead of passing through the next person who touches it. Never remove or bypass the ground pin of a plug.

Electrical safety

A computer runs on low voltages inside, but its power supply connects to mains power, and some parts store energy long after the plug is pulled.

• Unplug before opening any device. Switching off is not enough: a standard desktop (Advanced Technology eXtended, ATX) power supply keeps a standby voltage on the motherboard as long as the cord is connected. Disconnect every power cord — servers often have two power supplies — and remember that equipment on an uninterruptible power supply (UPS) stays live even when the UPS itself is unplugged from the wall. After unplugging, press the power button for a few seconds to drain the remaining charge on the board.
• Never open a power supply unit (PSU) or an old CRT monitor. Both contain large capacitors that can hold a dangerous, even lethal, charge long after unplugging. A faulty PSU is replaced, never repaired in the field. See Power Supplies and Power.
• Laser printers use high voltage for the imaging process and a fuser that is hot enough to burn; let the printer cool down and follow the vendor's procedure. See Printers.
• Remove jewelry — rings, bracelets, watches, necklaces. Metal conducts electricity, can short a circuit, and can catch on components or fans.
• Check cords and plugs for damage, do not overload power strips, and keep liquids away from equipment. In the UK, a standard plug (BS 1363) must by law contain a fuse (BS 1362); replace a blown one only with a fuse of the same rating, never with wire or foil.

Physical safety

Lifting and carrying

Servers, printers, monitors and boxes of paper are heavier than they look, and back injuries are among the most common injuries in IT work. Lift with your legs, not your back: bend your knees, keep your back straight, hold the load close to your body, and do not twist while lifting. Many training materials name about 50 pounds (roughly 23 kg) as the point to get help or use a cart, but follow your organization's guidance for weight limits. Mounting servers in a rack is a two-person job, and a rack loaded from the top can tip over: fill it from the bottom and use its stabilizers.

Cable management and trip hazards

Cables across a walkway are a trip hazard for people and a risk for equipment that gets pulled off a desk. Route cables along walls or under desks, use cable covers where a cable must cross a floor, and bundle cables neatly in racks. Do not run power cables under carpets or rugs, where damage goes unnoticed and heat cannot escape. Keep the area around your workplace clear, and close cabinet doors and floor tiles when you leave.

Personal protective equipment

Personal protective equipment (PPE) protects you where the hazard itself cannot be removed:

• Safety glasses when using compressed air or cutting cable ties and cables.
• Gloves against sharp case edges, broken glass and toner or battery chemicals.
• A dust mask or respirator when cleaning toner spills or very dusty equipment.
• An antistatic wrist strap, which protects the components rather than you.

Chemical safety

IT work involves more chemicals than you would expect: toner, ink, batteries, thermal paste, isopropyl alcohol, and cleaning products. Each has specific risks:

• Toner is a very fine powder. Do not inhale it, and do not clean a spill with an ordinary vacuum cleaner: the fine particles pass through its filter, and toner dust can even ignite. Use a vacuum made for toner. Wash toner off skin and clothes with cold water; warm water can melt it into the fabric.
• Batteries can leak corrosive chemicals or, for lithium-ion, catch fire (see below).
• Cleaning products: isopropyl alcohol is flammable; use it sparingly, only on unpowered equipment, and let it evaporate before switching on. Compressed air cans get very cold and can spray liquid propellant if tilted.

For every hazardous product, the manufacturer publishes a safety data sheet (SDS), formerly called a material safety data sheet (MSDS). It uses a standard structure of 16 sections, based on the United Nations' Globally Harmonized System (GHS), covering among other things the hazards, safe handling and storage, first aid, firefighting measures, what to do after a spill, and disposal. Workplaces must keep them available for the products they use. When a toner cartridge breaks or a battery leaks, the SDS tells you what to do.

Fire safety

Fire extinguishers are rated for the kind of fire they can put out, and using the wrong one can make things worse. Water conducts electricity, so it must never be used on a fire in equipment that is still powered. A burning lithium-ion battery is the one case where water is the right choice, once the device is disconnected from mains power — see Battery safety.

In the United States, fires in energized electrical equipment are class C; a carbon dioxide (CO2) extinguisher is the usual choice for IT equipment because it leaves no residue. After using one in a small closed room, leave and ventilate the room, because CO2 displaces the air you breathe; and do not hold the horn, which gets very cold. Other regions label fires differently: the European standard EN 2, also used in the UK, has no separate class for electrical fires (its class C means flammable gases), and extinguishers there show whether and up to which voltage they are safe on electrical equipment; some other systems, such as Australia's, call electrical fires class E. Learn the labels that apply where you work.

If there is a fire: raise the alarm, disconnect power only if it is safe to do so, and use an extinguisher only on a small fire with a clear escape route behind you. The usual technique is PASS: Pull the pin, Aim at the base of the fire, Squeeze the handle, Sweep from side to side. When in doubt, leave and let the fire service handle it.

Battery safety

Lithium-ion batteries in laptops, phones and tablets store a lot of energy in a small space. When one is damaged, overheated or defective, it can go into thermal runaway: it heats itself, vents flammable gas and can burn fiercely and reignite. Warning signs are a swollen battery (a bulging case, a lifted touchpad or screen), heat, hissing or a sweet chemical smell.

• Stop using and charging a device with a swollen battery.
• Never puncture, bend, crush or press a swollen battery back into shape.
• Remove it only if the vendor's procedure allows it and it can be done without force; store it in a fireproof container, away from flammable material.
• Dispose of batteries through a battery recycling or hazardous waste channel, never in regular trash. Cover the terminals with tape to prevent short circuits during transport.
• Never ship or fly a device with a swollen or damaged battery as normal parcel or luggage; damaged lithium batteries need dangerous-goods shipping. Ask the vendor for its return merchandise authorization (RMA) procedure.
• The large lead-acid batteries in uninterruptible power supplies (UPSs) are heavy and contain acid; they, too, go to recycling.

See Laptops and Mobile Devices for battery care and replacement.

Environmental responsibility

E-waste (electronic waste) is discarded electrical and electronic equipment: computers, monitors, phones, printers, cables, batteries and toner cartridges. It contains hazardous substances such as lead, mercury (in old display backlights) and cadmium, which must not end up in landfill, and valuable materials such as copper and gold that can be recovered. Many countries regulate it: in the European Union, the Waste Electrical and Electronic Equipment (WEEE) directive makes producers responsible for collection and recycling; in the United States, the rules are set largely by the individual states, and certifications such as R2 (Responsible Recycling) and e-Stewards identify responsible recyclers.

• Use certified recyclers or the manufacturer's take-back program, and keep the certificates of recycling for the asset records.
• Return toner and ink cartridges through the vendor's recycling program.
• Consider reuse first: a working computer that no longer meets your organization's needs may serve somewhere else.
• Remove the data first. Before any device leaves the organization — for recycling, resale or donation — its storage must be securely wiped or destroyed, and that must be documented. Overwriting is reliable for hard disks but not for solid-state drives (SSDs), which need the drive's secure-erase or cryptographic-erase function, or physical destruction. Methods are covered in the Security topic.

Hazards and precautions at a glance