RetroTechCollection:Safety requirements

RTC:SAFETYRTC:SAFETY

This page is a RetroTechCollection policy.

All editors should follow it. Propose changes on the Village Pump before making them.

This policy sets out the safety information that RetroTechCollection pages must carry. Much of the equipment covered here runs from mains electricity, and CRT displays hold a high-voltage charge after they are switched off. Both can kill.

The requirement

A page whose procedure involves mains voltage or a CRT must carry a plain hazard statement before the first step that exposes the reader to it. The statement:

names the hazard: mains voltage on the primary side of the power supply, the charge held on the mains filter capacitors after unplugging, or the charge on the CRT anode
says what to do about it: unplug the machine, discharge the CRT, treat the primary-side capacitors as charged
links the page that covers it, usually CRT Discharge Procedure

One or two sentences are enough. Use a bold sentence or the {{Warning}} box:

'''Warning: the analogue board carries mains voltage, and the CRT holds a charge of up to 12,000 V
after the machine is unplugged. Unplug the machine and discharge the tube before touching the
board: see [[CRT Discharge Procedure]].'''

{{Warning
| header = Mains voltage
| text = The power supply's primary side runs at mains voltage, and its filter capacitors hold
a charge after unplugging. Unplug the supply and check the capacitors are discharged before
working on it.
}}

Where a procedure meets another hazard, such as a leaking battery, a solvent or hot solder, mention it at that step and link the page that covers it, for example Battery Explosion, Capacitor or Corrosion Damage. The General disclaimer applies to every page and does not need repeating.

State the real hazard and let the reader decide. Recapping a power supply or a monitor is ordinary restoration work, and the wiki documents it.

Common hazards

CRT displays

A CRT holds a charge on its anode after the set is unplugged: up to 12,000 V in a compact Macintosh, and 25,000 V or more in a large colour set. The charge can last for days. Discharge the tube before any internal work, following CRT Discharge Procedure. Handle the tube by its body, never by the neck, because a cracked tube can implode. CRT glass contains lead; dispose of tubes through an electrical waste recycling scheme.

Power supplies

The primary side of a mains power supply runs at the line voltage (230 V in the UK and Europe, 120 V in North America), and its reservoir capacitors hold roughly 325 V DC from a 230 V supply after unplugging. Replace a fuse only with the type and rating marked on the board. See Capacitor Failure Symptoms.

Batteries

Old backup batteries leak, and some vent or burst. Identify the chemistry (NiCd, NiMH, lithium, lead-acid) before handling or charging a battery, clean up electrolyte as described in Battery Explosion, Capacitor or Corrosion Damage, and recycle spent cells.

Chemicals

Isopropyl alcohol is flammable; use it with ventilation and away from ignition sources. Hydrogen peroxide used for Retrobrite irritates skin and eyes. Solder fumes and flux need ventilation or extraction, and lead solder calls for washing hands afterwards. Check the safety data sheet (SDS) for any chemical you have not used before.

Protective equipment

insulated tools rated for the voltage present
safety glasses, for work on CRTs, springs and anything that can shatter or spit
gloves suited to the chemical being used
fume extraction or good ventilation when soldering or using solvents

Emergency procedures

Electric shock

Disconnect the power source immediately, if it is safe to do so.
Check whether the casualty is conscious and breathing, without touching them directly.
Call the emergency services (999 or 112 in the UK, 911 in the US and Canada).
CPR should be given only by trained people, and only if the casualty is unconscious.
Everyone who has had an electric shock needs a medical assessment.

Electrical fire

Shut off the power, if the switch can be reached safely.
Use an extinguisher rated for electrical fires: CO2 or dry powder. (In the US these are marked Class C. In the UK and Europe, Class C means flammable gases.)
Clear the area and call the fire service.
Ventilate the area, because burning electronics give off toxic fumes.

Chemical on skin

Remove contaminated clothing and jewellery.
Flush the affected area with plenty of water for at least 15 minutes.
Get medical help immediately for serious exposure.
Give the safety data sheet to the medical staff.

Fumes inhaled

Move the casualty to fresh air immediately.
Get medical help immediately if they have difficulty breathing.
Contact a poison information service for advice (NHS 111 in the UK, Poison Control in the US).
Ventilate the affected area.