Electricity is in constant use so it is easy to forget that hazard or death often result from its misuse. The values for a "tingling" is felt and median "let-go" threshold (at which one cannot release the conductor) for men are listed below. Women are more sensitive than males; approximately 2/3 of the above currents is needed to produce the same effect ("Electrical Hazards 5.1," Technical Information, MIT Safety Office).

Direct Current:
1 mA & 76 mA

Alternating Current (60 Hz):
0.4 mA & 16 mA

Higher currents produce respiratory inhibition, then ventricular fibrillation, and ultimately cardiac arrest.

Although minute electrical shocks are generally considered annoying rather than harmful, such shocks constitute a warning of hazardous conditions. The device in question should be disconnected immediately and the cause ascertained by an electrician.

Remove power before working on electrical devices so that it cannot be turned on accidentally. Internal current-carrying devices such as capacitors must be discharged. Work on AC wiring should be isolated at the circuit breaker or fuse, not just at a switch.

All "home-made" electrical apparatus should be inspected and approved by an electrician prior to being placed in service.

Observe the following rules when working with electrical equipment:

Ungrounded wiring and two-wire extension cords are prohibited. Worn or frayed extension cords or those with broken connections or exposed wiring must not be used. All electrical devices must be grounded before they are turned on.

Extension cords are for temporary use, and are not to be used in place of permanent wiring.

Keep the use of extension cords to a minimum and cords as short as possible. Tie off excess cord out of pathways.

Volt Limit: Untrained persons may not work on live equipment carrying potentials greater than 50 V. Use only tools and equipment with non-conducting handles when working with electrical devices. If you feel an electrical "tingle" while working with a piece of equipment, disconnect it and consult with an electrician. In the U.S., three-terminal (115 V AC) electrical wiring should conform to the following color code:

White = neutral wire
Black = live/hot wire
Green = ground wire

(When working with existing wiring, do not trust that this color scheme has been used correctly.) Do not short circuit the leads to a battery. Without a fuse, the internal resistance of the battery will cause it to heat and possibly explode. Dangerous arcs or flashes may also be produced.

A ground-fault interrupter does not assure protection against electrocution.

All current transmitting parts of any electrical devices should be enclosed.

When checking an operating circuit, keep one hand either in a pocket or behind the back, to avoid grounding yourself.

Maintain a work space clear of extraneous material.

Never change wiring with the circuit plugged into a power source.

Never plug leads into a power source unless they are connected to an established circuit.

Remove rings, watches, or other such jewelry before working on electrical circuits.

Avoid contacting circuits with wet hands or wet materials.

Check circuits for proper grounding with respect to the power source.

Do not insert another fuse of larger capacity if an instrument keeps blowing fuses. This is a symptom requiring expert repairs.

Do not use or store highly flammable solvents near electrical equipment.

Multi-strip outlets should not be used in place of permanently installed receptacles.

Keep access to electrical panels and disconnect switches clear and unobstructed (three feet of floor space).

Make certain that all electrical equipment (lamps also) is properly grounded.

Be alert and aware of the dangers inherent in high voltage equipment.

In the event of a small electrical fire:
Turn off the power source and unplug the equipment.
Do not turn on the circuit until the fire is extiguished, the cause of the fire has been established and the fault corrected.
Report the fire.