Electrician Power Tool Safety

Electrician Power Tool Safety

Follow these details about power tool safety. SOURCE:



Tool Power Sources: Hazards and Precautions

Section Overview
Tools are powered by a variety of sources. Unique hazards exist depending on a tool's power source. This section describes these hazards and safety precautions for electric, fuel, and air (pneumatic) powered tools.

Electric shock is the primary hazard from electric powered tools. Most electric shocks from tools have been caused by the failure of insulation between the current- carrying parts and the metal frames of tools.

Double Insulation
Double insulated tools provide reliable shock protection without third- wire grounding. Conventional electric tools have a single layer of functional insulation and are metal encased. Double insulation can be provided by encasing the entire tool, or at least the part of the tool which is handled, in a nonconductive material, such as plastic, which is also shatterproof. The National Electric Code permits double insulation on portable tools and appliances. Double-insulated tools that have been tested by Underwriter's Laboratories carry the square- in-square UL mark.

Grounding and Ground Fault Circuit Interrupters (GFCIs)
Grounding of portable electric tools and the use of ground- fault circuit interrupters (GFCIs) provide the most convenient way of safeguarding the operator. A ground is a connection in an electrical circuit that leads to the earth, or to a large conducting object that is at zero volts with respect to the rest of the circuit. In every type of electrical system or device, accessible metal parts, such as frames, cases, and switches, are usually maintained at ground potential. If there is any defect or short circuit inside the tool, the current is drained from the metal frame through a ground wire and does not pass through the operator's body. If a ground is not used, the current "seeks" a ground. The operator's body can serve as a grounding wire and the current will flow through the operator, causing injury.

The Ground Fault Circuit Interrupter (GFCI) is a fast- acting device which monitors the flow of current. It monitors for any leakage of current and shuts the power down quickly. When a GFCI is used the current is shut off before a serious shock can occur. Remember, a GFCI shall always be used with electric tools. The third- wire ground of the tool will not totally protect the worker from shock.

To ensure that grounding and GFCI protection is working properly, practice these safety procedures:

Check all grounding connections regularly for tightness.

For a good connection, make sure that grounding connections are free of dirt and oil.

Most GFCIs have a TEST feature. Test the GFCI regularly.

If you have any doubts about the electrical safety of a tool, contact your supervisor and request an electrician to evaluate the equipment.

If you ever get shocked by a tool DO NOT continue to use it! Repair or replace the tool.

Extension Cords
Faulty or misused extension cords can present serious hazards. Here are some extension cord safety practices:

  1. Inspect cords regularly. Look for signs of stretching, insulation damage, and kinking.

  2. Keep cords and cables clean and free from kinks. Kinking can damage both the cord's insulation and internal wire.

  3. Never carry a tool by its cord!

  4. When using tools which require a third wire ground use only three wire extension cords with three- pronged, grounding plugs and three hole electric outlets. Never cut off the grounding plug from a cord! If you see a cord with the grounding plug missing, remove the cord from service.

  5. Pulling on electric cords can damage the cord insulation and cause electric sparks. Always remove the cord at the plug.

  6. Extension cords may present a tripping hazard. Make sure that cords are not located in walking paths or a non- trip cover is placed over cords.

  7. Always use the correct extension cord for the job. An undersized cord can cause a drop in tool power and overheating. Consult the cord manufacturer's recommendations for cord length and gauge.

Pneumatic Powered Tools: Hazards and Precautions
Pneumatic tools are tools powered by compressed air at pressures of up to 90 psi. Pneumatic impact tools include riveting guns, nail guns, chipping hammers, and jackhammers. Here are some important safety rules to remember when using pneumatic- powered tools:

The air hose presents hazards similar to electrical cords. The hose can be a tripping hazard so it must be kept out of the way or protected. The hose must be kept clear from the work to prevent damage from the tool. If a hose gets cut and is pressurized, it can whip around and cause injury. A short length of chain attached to the tool and hose can prevent this if the hose coupling breaks.

Care must be taken to always use hose built for the pressure involved. There have been instances where workmen have put a hand over a pinhole leak and had air forced into a finger by the high pressure.

Before disconnecting the air hose from the air line, make sure that the air pressure is off and any air pressure inside the line has been released. A safety check valve shall be installed in the air line at the manifold to shut- off the air pressure if a fracture occurs in the hose.

Pneumatic percussion tools such as air hammers, riveting guns and jackhammers operate by producing heavy impacts or by rapid pulsating motion. This causes a great deal of vibration. Rubber hand grips, air cushion devices, and vibration dampers shall be used where possible.

Air operated staplers and nailers can cause injury by the accidental firing of the fastener. The fastener can travel at very high velocity and can easily puncture tissue from a good distance. Never point a nailer or stapler at another person. Always be aware of where the fastener is going when you activate the tool.

In the use of pneumatic chipping tools there is a hazard from flying chips. Operators should wear safety goggles, and, if other emp shall loyees must be in the vicinity, they be similarly protected. If two employees are chipping in the same area, they shall work back to back so they are chipping away from each other.

Noise levels from pneumatic tools are usually elevated and should be evaluated to determine if hearing protection is required. OSHA says; at 85 decibels, hearing protection should be offered to the employees, and at 90 decibels, hearing protection is required.

Fuel Powered Tools: Hazards and Precautions
These types of tools can be powered by fuels such as propane or gasoline. The main hazards associated with fuel are flammability and combustion. Certain tools like a propane torch produce a flame, which can burn and serve as an ignition source. The following safety guidelines should be remembered when using fuel powered tools:

Never work near a source of ignition such as a heating element, fire, or sparks.

The Safety Committee will determine if fuel powered machinery can be allowed to be used at NHMFL and a Hot Work Permit may have to be issued. Contact the Safety Office in advance if planning to use any type of fuel powered equipment.

Avoid working near flammable materials and fuel storage areas like paper boxes, gas and propane tanks, and flammable chemical storage areas.

Always store fuels in a cool, protected location.

Fuels like gasoline contain harmful chemicals like benzene. Avoid breathing gasoline vapors. Userespiratory protection if needed.

Here are useful tips about power tool safety. SOURCE:

When and how should you inspect powered hand tools?


Inspect tools for any damage prior to each use.

Check the handle and body casing of the tool for cracks or other damage.

If the tool has auxiliary or double handles, check to see that they installed securely.

Inspect cords for defects: check the power cord for cracking, fraying, and other signs of wear or faults in the cord insulation.

Check for damaged switches and ones with faulty trigger locks.

Inspect the plug for cracks and for missing, loose or faulty prongs.

What should you do if you find a tool defective?


If a tool is defective, remove it from service, and tag it clearly "Out of service for repair".

Replace damaged equipment immediately - do not use defective tools "temporarily".

Have tools repaired by a qualified person - do not attempt field repairs.

What should you do before using powered hand tools?


Ensure that you have been properly trained to use the tool safely. Read the operator's manual before using the tool and operate the tool according to the manufacturer's instructions.

Ensure that the power tool has the correct guard, shield or other attachment that the manufacturer recommends.

Prevent shocks. Ensure that the tools are properly grounded using a three-prong plug, are double-insulated (and are labelled as such), or are powered by a low-voltage isolation transformer: this will protect users from an electrical shock.

Check electric tools to ensure that a tool with a 3-prong plug has an approved 3-wire cord and is grounded. The three-prong plug should be plugged in a properly grounded 3-pole outlet. If an adapter must be used to accommodate a two-hole receptacle, the adapter wire must be attached to a known, functioning ground. Never remove the third, grounding prong from a plug.

Replace open front plugs with dead front plugs. Dead front plugs are sealed and present less danger of shock or short circuit.

Open Front Plug

Dead Front Plug

Have a qualified electrician install a polarized outlet if the polarized, two-prong plug of a double-insulated tool does not fit in a two-hole receptacle. Double insulated tools use plugs having one prong that is visibly wider than the other. If the plug does not fit in a receptacle after reversing the plug, the wall receptacle may be an older, non-polarized type. These can only accommodate plugs with two prongs that are the same width.

Test all tools for effective grounding with a continuity tester or a ground fault circuit interrupter (GFCI) before use.

Use only the kind of battery that the tool manufacturer specifies for the battery-powered tool that you are using.

Recharge a battery-powered tool only with a charger that is specifically intended for the battery in that tool.

Remove the battery from the tool or ensure that the tool is switched off or locked off before changing accessories, making adjustments, or storing the tool.

Store a battery pack safely so that no metal parts, nails, screws, wrenches and so on can come in contact with the battery terminals; this could result in shorting the battery and possibly cause sparks, fires or burns.

What should you do while using powered hand tools?


Wear or use personal protective equipment (PPE) or clothing that is appropriate for the work you are doing; this may include items such as safety glasses or goggles, hearing protection, dust mask, gloves, safety boots or shoes, or rubber boots.

Switch off the tools before connecting them to a power supply.

If a power cord feels more than comfortably warm or if a tool is sparking excessively, have it checked by an electrician or other qualified person.

Disconnect the power supply before making adjustments or changing accessories.

Remove any wrenches and adjusting tools before turning on a tool.

Inspect the cord for fraying or damage before each use. Tag defective tools clearly with an "Out of service" tag and replace immediately with a tool in good running order.

During use, keep power cords clear of tools and the path that the tool will take.

Use clamps, a vice or other devices to hold and support the piece being worked on, when practical to do so. This will allow you to use both hands for better control of the tool and will help prevent injuries if a tool jams or binds in a work piece.

Use only approved extension cords that have the proper wire size for the length of cord and power requirements of the electric tool that you are using. This will prevent the cord from overheating.

For outdoor work, use outdoor extension cords marked "W-A" or "W".

Suspend power cords over aisles or work areas to eliminate stumbling or tripping hazards.

Eliminate octopus connections: if more than one receptacle plug is needed, use a power bar or power distribution strip that has an integral power cord and a built-in overcurrent protection.

Pull the plug, not the cord when unplugging a tool. Pulling the cord causes wear and may adversely affect the wiring to the plug - an electrical shock to the operator may result.

Follow good housekeeping procedures - keep the work area free of clutter and debris that could be tripping or slipping hazards.

Keep power cords away from heat, water, oil, sharp edges and moving parts. They can damage the insulation and cause a shock.

Ensure that cutting tools, drill bits, etc. are kept sharp, clean and well maintained.

Store tools in a dry, secure location when they are not being used.

What should you avoid when using powered tools?


Do not wear gloves, loose clothing or jewelry while using revolving power tools. Tie back long hair or wear appropriate hair protection to prevent hair from getting caught in moving parts of equipment.

Do not use a tool unless you have been trained to use it safely and know its limitations and hazards.

Avoid accidental starting by ensuring the tool is turned off before you plug it in. Also do not walk around with a plugged-in tool with your finger touching the switch.

Do not bypass the ON/OFF switch and operate the tools by connecting and disconnecting the power cord.

Do not disconnect the power supply of the tool by pulling or jerking the cord from the outlet.

Do not leave a running tool unattended. Do not leave it until it has been turned off, has stopped running completely, and has been unplugged.

Do not use electric tools in wet conditions or damp locations unless tool is connected to a ground fault circuit interrupter (GFCI).

Do not expose electric power tools to rain or wet conditions; wet tools increase the likelihood for getting an electric shock.

Avoid body contact with grounded surfaces like refrigerators, pipes and radiators when using electric powered tools; this will reduce the likelihood of shock if the operator's body is grounded.

Do not plug several power cords into one outlet by using single-to-multiple outlet adapters or converters ("cube taps").

Do not use light duty power cords.

Do not connect or splice extension cords together to make a longer connection: the resulting extension cord may not be able to provide sufficient current or power safely.

Do not carry electrical tools by the power cord.

Do not tie power cords in knots. Knots can cause short circuits and shocks. Loop the cords or use a twist lock plug.

Do Not Tie Power Cords

Never break off the third prong on a plug: replace broken 3-prong plugs and make sure the third prong is properly grounded.

Never use extension cords as permanent wiring: use extension cords only as a temporary power supply to an area that does not have a power outlet.

Do not walk on or allow vehicles or other moving equipment to pass over unprotected power cords. Cords should be put in conduits or protected by placing planks on each side of them.

Do not bush away sawdust, shavings or turnings while the tool is running. Never use compressed air for cleaning surfaces or removing sawdust, metal turnings, etc.

Do not operate tools in an area containing explosive vapours or gases.

Do not clean tools with flammable or toxic solvents.

Do not surprise or touch anyone who is operating a tool. Startling a tool operator could end up causing an accident or injury.




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