I have grounding presentations and articles for grounding on electrical items. Grounding regarding towers and lightning operations and grounding relating to protection on pipelines to prevent corrosion and protection. Which field do you or would you like?
TP
From Canada, Calgary
59TP
From Canada, Calgary
Let's talk safety when working around electricity. The key is doing the hazard assessment first. A lot of good people have been hurt by not assessing the risks.
On top of grounding and making sure items are properly connected, many places (usually in poor countries or communities) will have kids or people stealing ground rods or copper wire from sites because of the huge value on the open market. This is very common around electrical plants, power generator stations, or pipeline areas where grounding is in place to protect pipelines. When in doubt, always lock out and tag out all lines before inspecting or use the proper APPROVED METERS.
Why is it so important to work safely with or near electricity?
The electrical current in regular businesses and homes has enough power to cause death by electrocution. Even changing a light bulb without unplugging the lamp can be hazardous because coming in contact with the "hot" or live part of the socket could kill a person.
What do I need to know about electricity?
All electrical systems have the potential to cause harm. Electricity can be either "static" or "dynamic." Dynamic electricity is the uniform motion of electrons through a conductor (this is known as electric current). Conductors are materials that allow the movement of electricity through them. Most metals are conductors. This document is about dynamic electricity.
Note: Static electricity is an accumulation of charge on surfaces as a result of contact and friction with another surface. This contact/friction causes an accumulation of electrons on one surface and a deficiency of electrons on the other surface. Electric current cannot exist without an unbroken path to and from the conductor. Electricity will form a "path" or "loop." When you plug in a device (e.g., a power tool), the electricity takes the easiest path from the plug-in to the tool and back to the power source. This is also known as creating or completing an electrical circuit.
What kinds of injuries result from electrical currents?
People are injured when they become part of the electrical circuit. Humans are more conductive than the earth (the ground we stand on), which means if there is no other easy path, electricity will try to flow through our bodies.
There are four main types of injuries: electrocution (fatal), electric shock, burns, and falls. These injuries can happen in various ways:
- Direct contact with the electrical energy. When electricity travels through our bodies, it can interfere with the normal electrical signals between the brain and our muscles (e.g., the heart may stop beating properly, breathing may stop, or muscles may spasm).
- When the electricity arcs (jumps or "arcs") through a gas (such as air) to a person who is grounded (providing an alternative route to the ground for the electricity).
- Arc flashes result in intense heat (causing burns), intense light (can cause blindness), or ignition of other materials.
- Arc blasts cause the same conditions as an arc flash but are more intense and can also include a strong pressure wave. These pressure waves can damage machinery, throw a person, collapse a lung, or rupture eardrums.
- Thermal burns including flash burns from heat generated by an electric arc and flame burns from materials that catch on fire from heating or ignition by electrical currents. High voltage contact burns can burn internal tissues while leaving only very small injuries on the outside of the skin.
- Muscle contractions or a startle reaction can cause a person to fall from a ladder, scaffold, or aerial bucket. The fall can cause serious injuries.
What are some general safety tips for working with or near electricity?
- Inspect tools, power cords, and electrical fittings for damage or wear before each use. Repair or replace damaged equipment immediately.
- Always tape cords to walls or floors when necessary. Nails and staples can damage cords causing fire and shock hazards.
- Use cords or equipment that are rated for the level of amperage or wattage that you are using.
- Always use the correct size fuse. Replacing a fuse with one of a larger size can cause excessive currents in the wiring and possibly start a fire.
- Be aware that unusually warm or hot outlets may be a sign that unsafe wiring conditions exist. Unplug any cords from these outlets and do not use them until a qualified electrician has checked the wiring.
- Always use ladders made of wood or other non-conductive materials when working with or near electricity or power lines.
- Place halogen lights away from combustible materials such as clothes or curtains. Halogen lamps can become very hot and may be a fire hazard.
- The risk of electric shock is greater in areas that are wet or damp. Install Ground Fault Circuit Interrupters (GFCIs) as they will interrupt the electrical circuit before a current sufficient to cause death or serious injury occurs.
- Make sure that exposed receptacle boxes are made of non-conductive materials.
- Know where the breakers and boxes are located in case of an emergency.
- Label all circuit breakers and fuse boxes clearly. Each switch should be positively identified as to which outlet or appliance it is for.
- Do not use outlets or cords that have exposed wiring.
- Do not use power tools with the guards removed.
- Do not block access to circuit breakers or fuse boxes.
- Do not touch a person or electrical apparatus in the event of an electrical accident. Always disconnect the current first.
What are some tips for working with power tools?
- Switch tools OFF before connecting them to a power supply.
- Disconnect power supply before making adjustments.
- Ensure tools are properly grounded or double-insulated. The grounded tool must have an approved 3-wire cord with a 3-prong plug. This plug should be plugged into a properly grounded 3-pole outlet.
- Test all tools for effective grounding with a continuity tester or a ground fault circuit interrupter (GFCI) before use.
- Do not bypass the switch and operate the tools by connecting and disconnecting the power cord.
- Do not use electrical tools in wet conditions or damp locations unless the tool is connected to a GFCI.
- Do not clean tools with flammable or toxic solvents.
- Do not operate tools in an area containing explosive vapors or gases unless they are intrinsically safe and only if you follow the manufacturer's guidelines.
What are some tips for working with power cords?
- Keep power cords clear of tools during use.
- Suspend power cords over aisles or work areas to eliminate stumbling or tripping hazards.
- Replace open front plugs with dead front plugs. Dead front plugs are sealed and present less danger of shock or short circuit.
- Do not use light-duty power cords.
- Do not carry electrical tools by the power cord.
- Do not tie power cords in tight knots. Knots can cause short circuits and shocks. Loop the cords or use a twist lock plug.
What is a Ground Fault Circuit Interrupter (GFCI)?
A Ground Fault Circuit Interrupter (GFCI) works by detecting any loss of electrical current in a circuit. When a loss is detected, the GFCI turns the electricity off before severe injuries or electrocution can occur. A painful shock may occur during the time that it takes for the GFCI to cut off the electricity, so it is important to use the GFCI as an extra protective measure rather than a replacement for safe work practices.
GFCI wall outlets can be installed in place of standard outlets to protect against electrocution for just that outlet or a series of outlets in the same branch. A GFCI Circuit Breaker can be installed on some circuit breaker electrical panels to protect an entire branch circuit. Plug-in GFCIs can be plugged into wall outlets where appliances will be used.
When and how do I test the Ground Fault Circuit Interrupter (GFCI)?
Test the GFCI monthly. First plug a "night light" or lamp into the GFCI-protected wall outlet (the light should be turned on), then press the "TEST" button on the GFCI. If the GFCI is working properly, the light should go out. If not, have the GFCI repaired or replaced. Reset the GFCI to restore power.
If the "RESET" button pops out but the light does not go out, the GFCI has been improperly wired and does not offer shock protection at that wall outlet. Contact a qualified electrician to correct any wiring errors.
What is a sample checklist for basic electrical safety?
Inspect Cords and Plugs
- Check power cords and plugs daily. Discard if worn or damaged. Have any cord that feels more than comfortably warm checked by an electrician.
Eliminate Octopus Connections
- Do not plug several power cords into one outlet.
- Pull the plug, not the cord.
- Do not disconnect the power supply by pulling or jerking the cord from the outlet. Pulling the cord causes wear and may cause a shock.
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 to temporarily supply power to an area that does not have a power outlet.
- Keep power cords away from heat, water, and oil. They can damage the insulation and cause a shock.
- Do not allow vehicles to pass over unprotected power cords. Cords should be put in conduit or protected by placing planks alongside them.
[Link updated to site home]
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From Canada, Calgary
On top of grounding and making sure items are properly connected, many places (usually in poor countries or communities) will have kids or people stealing ground rods or copper wire from sites because of the huge value on the open market. This is very common around electrical plants, power generator stations, or pipeline areas where grounding is in place to protect pipelines. When in doubt, always lock out and tag out all lines before inspecting or use the proper APPROVED METERS.
Why is it so important to work safely with or near electricity?
The electrical current in regular businesses and homes has enough power to cause death by electrocution. Even changing a light bulb without unplugging the lamp can be hazardous because coming in contact with the "hot" or live part of the socket could kill a person.
What do I need to know about electricity?
All electrical systems have the potential to cause harm. Electricity can be either "static" or "dynamic." Dynamic electricity is the uniform motion of electrons through a conductor (this is known as electric current). Conductors are materials that allow the movement of electricity through them. Most metals are conductors. This document is about dynamic electricity.
Note: Static electricity is an accumulation of charge on surfaces as a result of contact and friction with another surface. This contact/friction causes an accumulation of electrons on one surface and a deficiency of electrons on the other surface. Electric current cannot exist without an unbroken path to and from the conductor. Electricity will form a "path" or "loop." When you plug in a device (e.g., a power tool), the electricity takes the easiest path from the plug-in to the tool and back to the power source. This is also known as creating or completing an electrical circuit.
What kinds of injuries result from electrical currents?
People are injured when they become part of the electrical circuit. Humans are more conductive than the earth (the ground we stand on), which means if there is no other easy path, electricity will try to flow through our bodies.
There are four main types of injuries: electrocution (fatal), electric shock, burns, and falls. These injuries can happen in various ways:
- Direct contact with the electrical energy. When electricity travels through our bodies, it can interfere with the normal electrical signals between the brain and our muscles (e.g., the heart may stop beating properly, breathing may stop, or muscles may spasm).
- When the electricity arcs (jumps or "arcs") through a gas (such as air) to a person who is grounded (providing an alternative route to the ground for the electricity).
- Arc flashes result in intense heat (causing burns), intense light (can cause blindness), or ignition of other materials.
- Arc blasts cause the same conditions as an arc flash but are more intense and can also include a strong pressure wave. These pressure waves can damage machinery, throw a person, collapse a lung, or rupture eardrums.
- Thermal burns including flash burns from heat generated by an electric arc and flame burns from materials that catch on fire from heating or ignition by electrical currents. High voltage contact burns can burn internal tissues while leaving only very small injuries on the outside of the skin.
- Muscle contractions or a startle reaction can cause a person to fall from a ladder, scaffold, or aerial bucket. The fall can cause serious injuries.
What are some general safety tips for working with or near electricity?
- Inspect tools, power cords, and electrical fittings for damage or wear before each use. Repair or replace damaged equipment immediately.
- Always tape cords to walls or floors when necessary. Nails and staples can damage cords causing fire and shock hazards.
- Use cords or equipment that are rated for the level of amperage or wattage that you are using.
- Always use the correct size fuse. Replacing a fuse with one of a larger size can cause excessive currents in the wiring and possibly start a fire.
- Be aware that unusually warm or hot outlets may be a sign that unsafe wiring conditions exist. Unplug any cords from these outlets and do not use them until a qualified electrician has checked the wiring.
- Always use ladders made of wood or other non-conductive materials when working with or near electricity or power lines.
- Place halogen lights away from combustible materials such as clothes or curtains. Halogen lamps can become very hot and may be a fire hazard.
- The risk of electric shock is greater in areas that are wet or damp. Install Ground Fault Circuit Interrupters (GFCIs) as they will interrupt the electrical circuit before a current sufficient to cause death or serious injury occurs.
- Make sure that exposed receptacle boxes are made of non-conductive materials.
- Know where the breakers and boxes are located in case of an emergency.
- Label all circuit breakers and fuse boxes clearly. Each switch should be positively identified as to which outlet or appliance it is for.
- Do not use outlets or cords that have exposed wiring.
- Do not use power tools with the guards removed.
- Do not block access to circuit breakers or fuse boxes.
- Do not touch a person or electrical apparatus in the event of an electrical accident. Always disconnect the current first.
What are some tips for working with power tools?
- Switch tools OFF before connecting them to a power supply.
- Disconnect power supply before making adjustments.
- Ensure tools are properly grounded or double-insulated. The grounded tool must have an approved 3-wire cord with a 3-prong plug. This plug should be plugged into a properly grounded 3-pole outlet.
- Test all tools for effective grounding with a continuity tester or a ground fault circuit interrupter (GFCI) before use.
- Do not bypass the switch and operate the tools by connecting and disconnecting the power cord.
- Do not use electrical tools in wet conditions or damp locations unless the tool is connected to a GFCI.
- Do not clean tools with flammable or toxic solvents.
- Do not operate tools in an area containing explosive vapors or gases unless they are intrinsically safe and only if you follow the manufacturer's guidelines.
What are some tips for working with power cords?
- Keep power cords clear of tools during use.
- Suspend power cords over aisles or work areas to eliminate stumbling or tripping hazards.
- Replace open front plugs with dead front plugs. Dead front plugs are sealed and present less danger of shock or short circuit.
- Do not use light-duty power cords.
- Do not carry electrical tools by the power cord.
- Do not tie power cords in tight knots. Knots can cause short circuits and shocks. Loop the cords or use a twist lock plug.
What is a Ground Fault Circuit Interrupter (GFCI)?
A Ground Fault Circuit Interrupter (GFCI) works by detecting any loss of electrical current in a circuit. When a loss is detected, the GFCI turns the electricity off before severe injuries or electrocution can occur. A painful shock may occur during the time that it takes for the GFCI to cut off the electricity, so it is important to use the GFCI as an extra protective measure rather than a replacement for safe work practices.
GFCI wall outlets can be installed in place of standard outlets to protect against electrocution for just that outlet or a series of outlets in the same branch. A GFCI Circuit Breaker can be installed on some circuit breaker electrical panels to protect an entire branch circuit. Plug-in GFCIs can be plugged into wall outlets where appliances will be used.
When and how do I test the Ground Fault Circuit Interrupter (GFCI)?
Test the GFCI monthly. First plug a "night light" or lamp into the GFCI-protected wall outlet (the light should be turned on), then press the "TEST" button on the GFCI. If the GFCI is working properly, the light should go out. If not, have the GFCI repaired or replaced. Reset the GFCI to restore power.
If the "RESET" button pops out but the light does not go out, the GFCI has been improperly wired and does not offer shock protection at that wall outlet. Contact a qualified electrician to correct any wiring errors.
What is a sample checklist for basic electrical safety?
Inspect Cords and Plugs
- Check power cords and plugs daily. Discard if worn or damaged. Have any cord that feels more than comfortably warm checked by an electrician.
Eliminate Octopus Connections
- Do not plug several power cords into one outlet.
- Pull the plug, not the cord.
- Do not disconnect the power supply by pulling or jerking the cord from the outlet. Pulling the cord causes wear and may cause a shock.
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 to temporarily supply power to an area that does not have a power outlet.
- Keep power cords away from heat, water, and oil. They can damage the insulation and cause a shock.
- Do not allow vehicles to pass over unprotected power cords. Cords should be put in conduit or protected by placing planks alongside them.
[Link updated to site home]
Correct Spelling and Grammar: Identified and fixed any spelling or grammatical mistakes in the text.
Handle Line Breaks:
Ensured there is a single line break between paragraphs.
Preserved the Meaning: Corrected the grammar and spelling while ensuring the original meaning and tone of the message remained unchanged.
From Canada, Calgary
Hi, Raghu,
Here is the last part of the training information you wanted for your company.
Sorry it took a while; I was out doing other stuff.
It only took me about 10 minutes to find the materials, but my library is so big, and links are in the thousands, so it takes a couple of minutes to search for the right materials.
I sure hope this helps. If not, type back again, and I will try to find better materials.
At its worst, a ground fault requires you to wait for the commercial to play before the training material.
But this is a worst-case situation when ground fault operations are destroyed or stolen.
Ground Fault Causes Electrical Fire - Video
http://wmmic.com <link updated to site home>
http://elcosh.org <link updated to site home>
http://miningquiz.com <link updated to site home>
Depending on where you live on the globe, here is a great article on grounding and wiring.
Groundloop information pages
Why is grounding used?
Terminology
In Britain, people have 'earth,' and in North America, they have 'ground.' They are exactly the same thing; only different terms are used in different countries.
Purposes of Grounding
The grounding system has three main purposes:
1. Overvoltage protection
Lightning, line surges, or unintentional contact with higher voltage lines can cause dangerously high voltages in the electrical distribution system wires. Grounding provides an alternative path around the electrical system of your home or workplace, minimizing damage from such occurrences.
2. Voltage stabilization
There are many sources of electricity. Every transformer can be considered a separate source. If there were not a common reference point for all these voltage sources, it would be extremely difficult to calculate their relationships to each other. The earth is the most omnipresent conductive surface, and so it was adopted in the very beginnings of electrical distribution systems as a nearly universal standard for all electric systems.
3. Current path to facilitate the operation of overcurrent devices
This purpose of grounding is the most important one to understand. The grounding system provides a certain level of safety to humans and property in case of equipment damages.
Grounding operation in the electrical distribution network
The primary reason why grounding is used in the electrical distribution network is safety: when all metallic parts in electrical equipment are grounded, then if the insulation inside the equipment fails, there are no dangerous voltages present in the equipment case. If the live wire touches the grounded case, then the circuit is effectively shorted, and the fuse will immediately blow. When the fuse blows, the dangerous voltages are eliminated.
The safety is the primary function of grounding. Grounding systems are designed to provide the necessary safety functions. Grounding also has other functions in some applications, but safety should not be compromised in any case. Grounding is often used to provide a common ground reference potential for all equipment, but the existing building grounding systems might not provide good enough ground potential for all equipment, which might lead to ground potential difference and ground loop problems, common problems in computer networks and audio/video systems.
How electric shock happens
The "hot" wire is at 120 volts or 230 volts (depends on the mains voltage used in your country), and the other wire is neutral or ground. If a person were to touch the neutral wire only, no shock would result simply because there is no voltage on it. If he were to touch the hot wire only, again nothing would happen to him unless some other part of his body were to become grounded. A person is considered to be grounded if he comes in contact with a water pipe, metal conduit, the neutral or ground wire, or stands barefoot on a concrete floor.
In other words, neither wire is a shock hazard unless a person is grounded, and then only the hot is a potential shock hazard. Of course, if a person were to touch both wires at the same time, he would be shocked simply because his body is completing connection between "hot" and "ground" wires.
Grounding and interference susceptibility
Whenever audio equipment is operated without a ground (floating chassis), strange things can happen. Under certain conditions, the amplifier will be more susceptible to radio frequency interference (picking up radio stations or CB radio). Also, without a suitable ground, amplifiers sometimes "hum" more when the musician picks up his instrument and provides a "pseudo" ground through himself.
The only solution is to find a ground point to connect to the chassis. Sometimes this may just cause more problems than it helps.
Grounding in wiring
Today's modern (US) mains cable consists of three separate wires: black, white, and green. The green wire is always connected to the large ground pin on the plug, and the other (green) end connected to the chassis of the equipment. The black wire is always considered to be the "hot wire," and as such, is always the leg that is connected to the switch and fuse. The white wire is always the neutral or common wire.
European coloring is a little bit different. The ground wire is here a green wire with a yellow stripe. The neutral wire is blue. The live wire is brown (additional colors for the live wires used in 3-phase systems are black and black with a white stripe).
Any modification of the above 3-wire mains system completely eliminates the protection given by the three-wire configuration. The integrity of the separate ground path is also directly related to the quality of the receptacle and the wiring system in the building itself.
The neutral (grounded conductor) must be solidly connected (bonded) to the home's ground system at the first disconnect (main panel). This keeps large voltage differences from developing between the neutral and ground.
Currents in grounding wire
Ground wires should not carry current except during faults. If the ground wire carries any current, there will be a potential difference between different grounding points (because the current flowing in the wire causes a voltage drop due to wire resistance). This is why a common wire that works as neutral and grounding wire is a very bad thing.
When there is separate wiring for grounding, you can't completely avoid the current flowing in grounding wires! There will always be some capacitive leakage current from the live wire to the ground wire. This capacitive leakage current is caused by the fact that the wiring, transformers, and interference filters all have some capacitance between the ground and live wire. The amount of current is limited to be quite low (limited to be between 0.6 mA to 10 mA, depending on equipment type) so it does not cause dangers and big problems. Because of this leakage current, there is always some current flowing in the ground wire, and the ground potentials of different electrical power outlets are never equal.
The leakage current can also cause other types of problems. In some situations, there are ground fault detect interrupter (GFCI) circuits in use; the leakage current caused by many equipment together can make the GFCI cut the current. Typically, GFCI circuits are designed to cut current when there is a 30 mA or more difference in currents flowing in live and neutral wires (the difference of those currents must flow to the ground). Some GFCI circuits can cut the mains feed even at 15 mA leakage current, which may mean that if you connect many computer equipment (each of them having 0.5 to 2 mA of leakage) to a GFCI-protected power outlet, you can cause the GFCI to cut the power feed.
Ground wire resistance
In Europe, it is not important how many ohms the grounding is, but the maximum current before the unit switches off is important. So a grounding of 230 volts and a safety of 24 volts. We say it must be less than 30 mA in our body. So for 16 amps and 24 volts, it is 1.5 ohms. This means that the maximum voltage on the case is 24 volts even when all current is flowing through the grounding wire. In places where even this 24V is considered very dangerous (for example, in hospitals), the ground resistance must be made lower to ensure that there is never dangerous voltage present in the case. For example, in Finland, the grounding resistance for medical room outlets must be less than 0.2 ohms to be considered safe.
The above is the objective, and all the fluff around it is just to make it difficult. Ground means something connected to the surrounding, and it must be less than x ohms measured with AC, and the wire must handle the short-circuit current present in the circuit without overheating.
A great site about electricity and grounding needs
Electrical Safety
and a great paper on electrical grounding outside
http://www.usbr.gov/ssle/safety/RSHS/appC.pdf
and more training for construction sites and safety
http://www.freeoshainfo.com/pubpages/Files/Electrical/ElectricaPPTConstruction.ppt
http://www.isrisafety.org/assets/files/presentations/70E%20ELECTRICAL%20SAFETY.ppt
http://www.miningelectrical.org/Files/GOOD%20GROUNDING%20PRACTICES.ppt
I hope this helps with the training materials you were looking for. Let me know if you need any more information.
From Canada, Calgary
Here is the last part of the training information you wanted for your company.
Sorry it took a while; I was out doing other stuff.
It only took me about 10 minutes to find the materials, but my library is so big, and links are in the thousands, so it takes a couple of minutes to search for the right materials.
I sure hope this helps. If not, type back again, and I will try to find better materials.
At its worst, a ground fault requires you to wait for the commercial to play before the training material.
But this is a worst-case situation when ground fault operations are destroyed or stolen.
Ground Fault Causes Electrical Fire - Video
http://wmmic.com <link updated to site home>
http://elcosh.org <link updated to site home>
http://miningquiz.com <link updated to site home>
Depending on where you live on the globe, here is a great article on grounding and wiring.
Groundloop information pages
Why is grounding used?
Terminology
In Britain, people have 'earth,' and in North America, they have 'ground.' They are exactly the same thing; only different terms are used in different countries.
Purposes of Grounding
The grounding system has three main purposes:
1. Overvoltage protection
Lightning, line surges, or unintentional contact with higher voltage lines can cause dangerously high voltages in the electrical distribution system wires. Grounding provides an alternative path around the electrical system of your home or workplace, minimizing damage from such occurrences.
2. Voltage stabilization
There are many sources of electricity. Every transformer can be considered a separate source. If there were not a common reference point for all these voltage sources, it would be extremely difficult to calculate their relationships to each other. The earth is the most omnipresent conductive surface, and so it was adopted in the very beginnings of electrical distribution systems as a nearly universal standard for all electric systems.
3. Current path to facilitate the operation of overcurrent devices
This purpose of grounding is the most important one to understand. The grounding system provides a certain level of safety to humans and property in case of equipment damages.
Grounding operation in the electrical distribution network
The primary reason why grounding is used in the electrical distribution network is safety: when all metallic parts in electrical equipment are grounded, then if the insulation inside the equipment fails, there are no dangerous voltages present in the equipment case. If the live wire touches the grounded case, then the circuit is effectively shorted, and the fuse will immediately blow. When the fuse blows, the dangerous voltages are eliminated.
The safety is the primary function of grounding. Grounding systems are designed to provide the necessary safety functions. Grounding also has other functions in some applications, but safety should not be compromised in any case. Grounding is often used to provide a common ground reference potential for all equipment, but the existing building grounding systems might not provide good enough ground potential for all equipment, which might lead to ground potential difference and ground loop problems, common problems in computer networks and audio/video systems.
How electric shock happens
The "hot" wire is at 120 volts or 230 volts (depends on the mains voltage used in your country), and the other wire is neutral or ground. If a person were to touch the neutral wire only, no shock would result simply because there is no voltage on it. If he were to touch the hot wire only, again nothing would happen to him unless some other part of his body were to become grounded. A person is considered to be grounded if he comes in contact with a water pipe, metal conduit, the neutral or ground wire, or stands barefoot on a concrete floor.
In other words, neither wire is a shock hazard unless a person is grounded, and then only the hot is a potential shock hazard. Of course, if a person were to touch both wires at the same time, he would be shocked simply because his body is completing connection between "hot" and "ground" wires.
Grounding and interference susceptibility
Whenever audio equipment is operated without a ground (floating chassis), strange things can happen. Under certain conditions, the amplifier will be more susceptible to radio frequency interference (picking up radio stations or CB radio). Also, without a suitable ground, amplifiers sometimes "hum" more when the musician picks up his instrument and provides a "pseudo" ground through himself.
The only solution is to find a ground point to connect to the chassis. Sometimes this may just cause more problems than it helps.
Grounding in wiring
Today's modern (US) mains cable consists of three separate wires: black, white, and green. The green wire is always connected to the large ground pin on the plug, and the other (green) end connected to the chassis of the equipment. The black wire is always considered to be the "hot wire," and as such, is always the leg that is connected to the switch and fuse. The white wire is always the neutral or common wire.
European coloring is a little bit different. The ground wire is here a green wire with a yellow stripe. The neutral wire is blue. The live wire is brown (additional colors for the live wires used in 3-phase systems are black and black with a white stripe).
Any modification of the above 3-wire mains system completely eliminates the protection given by the three-wire configuration. The integrity of the separate ground path is also directly related to the quality of the receptacle and the wiring system in the building itself.
The neutral (grounded conductor) must be solidly connected (bonded) to the home's ground system at the first disconnect (main panel). This keeps large voltage differences from developing between the neutral and ground.
Currents in grounding wire
Ground wires should not carry current except during faults. If the ground wire carries any current, there will be a potential difference between different grounding points (because the current flowing in the wire causes a voltage drop due to wire resistance). This is why a common wire that works as neutral and grounding wire is a very bad thing.
When there is separate wiring for grounding, you can't completely avoid the current flowing in grounding wires! There will always be some capacitive leakage current from the live wire to the ground wire. This capacitive leakage current is caused by the fact that the wiring, transformers, and interference filters all have some capacitance between the ground and live wire. The amount of current is limited to be quite low (limited to be between 0.6 mA to 10 mA, depending on equipment type) so it does not cause dangers and big problems. Because of this leakage current, there is always some current flowing in the ground wire, and the ground potentials of different electrical power outlets are never equal.
The leakage current can also cause other types of problems. In some situations, there are ground fault detect interrupter (GFCI) circuits in use; the leakage current caused by many equipment together can make the GFCI cut the current. Typically, GFCI circuits are designed to cut current when there is a 30 mA or more difference in currents flowing in live and neutral wires (the difference of those currents must flow to the ground). Some GFCI circuits can cut the mains feed even at 15 mA leakage current, which may mean that if you connect many computer equipment (each of them having 0.5 to 2 mA of leakage) to a GFCI-protected power outlet, you can cause the GFCI to cut the power feed.
Ground wire resistance
In Europe, it is not important how many ohms the grounding is, but the maximum current before the unit switches off is important. So a grounding of 230 volts and a safety of 24 volts. We say it must be less than 30 mA in our body. So for 16 amps and 24 volts, it is 1.5 ohms. This means that the maximum voltage on the case is 24 volts even when all current is flowing through the grounding wire. In places where even this 24V is considered very dangerous (for example, in hospitals), the ground resistance must be made lower to ensure that there is never dangerous voltage present in the case. For example, in Finland, the grounding resistance for medical room outlets must be less than 0.2 ohms to be considered safe.
The above is the objective, and all the fluff around it is just to make it difficult. Ground means something connected to the surrounding, and it must be less than x ohms measured with AC, and the wire must handle the short-circuit current present in the circuit without overheating.
A great site about electricity and grounding needs
Electrical Safety
and a great paper on electrical grounding outside
http://www.usbr.gov/ssle/safety/RSHS/appC.pdf
and more training for construction sites and safety
http://www.freeoshainfo.com/pubpages/Files/Electrical/ElectricaPPTConstruction.ppt
http://www.isrisafety.org/assets/files/presentations/70E%20ELECTRICAL%20SAFETY.ppt
http://www.miningelectrical.org/Files/GOOD%20GROUNDING%20PRACTICES.ppt
I hope this helps with the training materials you were looking for. Let me know if you need any more information.
From Canada, Calgary
Dear Penney, Great/Good write up sir. . .Thanks a lot for sharing such a wonderful ppt & links against grounding its full fill my query.Again thanks for quick responce. . . Keep on sharing. . .
From United States, Fpo
From United States, Fpo
You are quite welcome, my friend.
In Canada, I just assumed if you typed and asked, it was important for me or someone in the group to answer as soon as possible.
Secondly, count in management operations, and yes, it takes time to train, but somehow management just wants it done in the quickest route possible.
So, the ball is in your court for safety now and your workers.
Good Luck,
TP
From Canada, Calgary
In Canada, I just assumed if you typed and asked, it was important for me or someone in the group to answer as soon as possible.
Secondly, count in management operations, and yes, it takes time to train, but somehow management just wants it done in the quickest route possible.
So, the ball is in your court for safety now and your workers.
Good Luck,
TP
From Canada, Calgary
We all know to do the hazard assessment for the job and JSA, but it's hard sometimes to sit in an office and see the risk of injuries and how they impact the human body.
Well, here is a site that does it for you. Do the risk assessment. These guys and gals are great at doing the risk assessment on the safety risks to workers and injuries: [Construction Solutions](http://www.cpwrconstructionsolutions.org/index.php).
I know us long-winded Canadian boys always want people to live long lives and stay safe and injury-free. Silly Canucks.
From Canada, Calgary
Well, here is a site that does it for you. Do the risk assessment. These guys and gals are great at doing the risk assessment on the safety risks to workers and injuries: [Construction Solutions](http://www.cpwrconstructionsolutions.org/index.php).
I know us long-winded Canadian boys always want people to live long lives and stay safe and injury-free. Silly Canucks.
From Canada, Calgary
CiteHR.AI
(Fact Checked)-[Response] The information shared about risk assessment and safety in the workplace is relevant and valuable for ensuring worker well-being and compliance. (1 Acknowledge point)
Dear Penney,
I must appreciate your sharing mentality. Just now, I was reading/seeing your PPTs; it's all really helpful to me. I am sure that if I prepare my own, it will surely take at least 20 days, but I got all this in an hour.
Even many of our colleagues, especially EHS professionals, are not ready to share their expertise with words (even my close friends/seniors). But you are... "no words to say."
You are truly great, and we need your contribution forever. Please continue to guide/advise us. Always share your expertise with us.
Thank you.
Best regards,
[Your Name]
From United States, Fpo
I must appreciate your sharing mentality. Just now, I was reading/seeing your PPTs; it's all really helpful to me. I am sure that if I prepare my own, it will surely take at least 20 days, but I got all this in an hour.
Even many of our colleagues, especially EHS professionals, are not ready to share their expertise with words (even my close friends/seniors). But you are... "no words to say."
You are truly great, and we need your contribution forever. Please continue to guide/advise us. Always share your expertise with us.
Thank you.
Best regards,
[Your Name]
From United States, Fpo
It is no surprise to any of you that I am a former Police Officer turned safety professional. I've seen thousands of injured people from a variety of accidents.
Think really hard about the attached video and message. Are you the cause of someone's death? Are you the last words in a death sentence?
[YouTube - AT&T Don't Text While Driving Documentary](http://www.youtube.com/watch?v=DebhWD6ljZs)
From Canada, Calgary
Think really hard about the attached video and message. Are you the cause of someone's death? Are you the last words in a death sentence?
[YouTube - AT&T Don't Text While Driving Documentary](http://www.youtube.com/watch?v=DebhWD6ljZs)
From Canada, Calgary
dear all, i am busy with my MBA and OHSAS, EMS auditor programs... will catch u all from Jan 25thhh... till then keep sharing.... Regards, Firoz
From India, Bangalore
From India, Bangalore
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CiteHR.AI
(Fact Checked)-The information provided regarding electrical safety and working with electricity is accurate and comprehensive. Thank you for sharing valuable insights on this critical topic. (1 Acknowledge point)