Meralco:Consumer Tips

When planning and performing work on electrical systems and equipment, keep these principles in mind:

Plan every job.
Think about what could go wrong.
Use the right tools for the job.
Use procedures, drawings and other documents as tools to do the job.
Isolate the equipment from energy sources.
Identify the electrical shod and arc flash, as well as other hazards that may be present.
Minimize the hazard by guarding or establishing approach limitations.
Test every circuit and every conductor, every time before you touch.
Use personal protective equipment (PPE) as a last line of defense in case something goes wrong.
Be sure you are properly trained and qualified for the job.

Source:
The National Electrical Safety Foundation (NESF)-Workplace Safety Reminders

Do not guess about whether a circuit is live (energized) or not. Consider every equipment/line energized until proven otherwise.
Use proper instrument for testing circuits.
Never touch any wire of a circuit unless you are certain that it is de-energized.
Always use personal protective equipment (PPE) when dealing with electricity. These PPEs include rubber gloves, rubber mats, rubber blankets, fuse tongs, insulated tools and the like.
Lock open main switches and place tags before working on power circuits so that no one else may close them while you are working. Before closing a switch, make certain other workmen are clear of circuits.
Never work alone on any electrical equipment/circuits with more than 50 volts. The buddy system of working on electrical lines, installations is the best and safest way.
Use warning or safety signs and rope off or barricade dangerous areas.
In installing temporary electrical wiring or equipment, make every job safe for everyone.
Always observe strictly the applicable rules of the Philippine Electrical Code, National Electrical Safety Code and other applicable electrical standards.
Allow only qualified and properly trained men to work on electrical equipment.
Always arrange for proper maintenance of equipment, loads and wires with careful follow-up to see to it that insulation is in proper condition. Loose conductors can cause serious electrical accidents.
Never bridge a fuse with wire or other metal.
Don't test power lines with lamps to determine whether they are energized. A 110-volt test lamp place across a 220-volt line will blow-up. Use reliable circuit or voltage testers for testing or identifying circuits.
Always have periodic electrical inspections made by men qualified by experience and training to do such work.
The frames or cases of all electrical equipment or structures should be substantially grounded. The ground wire should be of low resistance and large enough to resist mechanical breakage and to carry off the heaviest current flow that might result from any insulation breakdown or other accidents.
Always protect electrical cords and cables from physical damage.