Thursday, June 25, 2009

Low Voltage Electrical Safety Tips

Applications of low voltage electrical items are commonly used in homes and commercial buildings. The voltage needed to run this items is usually 600 Volts and below. Most people carry the perception that low-voltage contact is much less dangerous than high-voltage contact, but is the opposite.

There are more injuries from low-voltage contacts (especially 347 V systems) than there are from high-voltage. This is why Energized Low-voltage systems are very dangerous. Two factors of these are as follows : First, there is a small working clearance between low-voltage components which leaves a little room for error when using tools. Second, Low-voltage equipment in some industrial services may be supplied by an electrical system that can feed incredible amounts of energy into a fault (caused by a short-circuit, for example).

Let us first understand some low-voltage overhead conductors utility poles we usually ignore: [1]Utility poles generally carry both low-voltage conductors (power lines) as well as communications lines (such as cable television and telephone). [2] High-voltage conductors are always installed at or near the top of the utility pole. [3] Low-voltage conductors are usually installed as a single conductor mounted one above the other. When working close to Energized Equipment, conductors, and utility poles, be guided of the following precautions:

- Un-insulated, energized parts of low-voltage electrical equipment and conductors must be guarded by approved cabinets or enclosures unless the energized parts are in a suitable room or enclosed area that is accessible only to qualified and authorized.

- Each entrance to a room or other guarded location containing un-insulated and exposed energized parts must be marked with warning signs limiting entry.

- If un-insulated, energized parts are not guarded with approved cabinets or enclosures: Suitable barriers or covers must be provided if a worker unfamiliar with the hazards is working within 1 meter (3.3 ft) of those parts, or the worker must be informed of the potential hazards and must follow written safe work procedures.

- Think ahead: Assess all of the risks associated with the task. Plan the whole job in advance so that you can take every precau5ion, including arranging for help in case of paralyzing shock. Consider the use of a pre-job safety meeting to discuss the job with all workers before starting the work.

- Know the system: Accurate, up-to-date information should be available to those who work on the system.

- Limit the exposure: Have live parts exposed for as little time as necessary. Be organized so that the job can be done efficiently.

- Cover exposed live metal: Use insulating barriers or shields to cover live parts.

- Cover grounded metal work: Grounded metal parts should be covered with insulating material as much as possible.

- Limit the energy to reduce the risk: All practical steps should be taken to ensure that the fault current at the point of work is kept as low as possible while the work is in progress. For example, measuring voltage, do it on the load side of the circuit-protective devices with smallest current rating. Current-limiting devices can be used to reduce the risk of an arc flash.

- Remove metal rings, bracelets, and wristwatch bands: These could cause a short-circuit where small clearances are involved. (If it is necessary to wear medic-alert bracelets, secure them with transparent surgical or adhesive tape or rubber bands.)

- Use one hand with your face and body turned to the side when operating a safety switch: Limit possible injuries by not placing body parts directly in front of energized equipment when there is danger of an arc flash.

- Avoid electrical contact when working in awkward positions: If you must work in an awkward on unbalanced position and reach with your tools, use insulating cover-up material on the tools to avoid contact with live conductors.

- Use the correct equipment and clothing: Insulated tools to avoid shocks and to prevent accidental short-circuits. Rubber gloves (leather gloves can be used when testing equipment). Cover-up blankets to avoid accidental contact with the equipment. Shock-resistant safety boots or shoes. Flame-resistant clothing if there is a fire hazard. Safety glasses, goggles, or a face shield to protect the worker from molten metal or ultraviolet light. Flame-resistant clothing if there is a risk of an electric arc that could cause a fire.

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