I have grounding presentation and articles for grounding on electrical items
Grounding regarding towers and lighthning operations
And grounding relating to protection on pipelines to prevent corrrosion and protection
Which field do or would you like
TP
From Canada, Calgary
11Grounding regarding towers and lighthning operations
And grounding relating to protection on pipelines to prevent corrrosion and protection
Which field do or would you like
TP
From Canada, Calgary
Lets talk safety when working around electricity
the key is doing the hazard assessment first
A lot of good people have been hurt not assessing the risks
On top of grounding and making sure items are properly connected a lot of place ( usually 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 or power generator stations or on pipeline areas were grounding is in place to protect pipelines If in doubt always loto 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 it. Most metals are conductors. This document is about dynamic electricity.
Note: Static electricity is 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., 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 (that would provide 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 ear drums.
• 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 prior to 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 is 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 exists. Unplug any cords to these outlets and do not use 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 cloths or curtains. Halogen lamps can become very hot and may be a fire hazard.
• 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 in 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 tool is connected to a GFCI.
• Do not clean tools with flammable or toxic solvents.
• Do not operate tools in an area containing explosive vapours 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 Interupter (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 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.
http://electricalrevision.co.uk <link updated to site home>
From Canada, Calgary
the key is doing the hazard assessment first
A lot of good people have been hurt not assessing the risks
On top of grounding and making sure items are properly connected a lot of place ( usually 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 or power generator stations or on pipeline areas were grounding is in place to protect pipelines If in doubt always loto 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 it. Most metals are conductors. This document is about dynamic electricity.
Note: Static electricity is 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., 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 (that would provide 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 ear drums.
• 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 prior to 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 is 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 exists. Unplug any cords to these outlets and do not use 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 cloths or curtains. Halogen lamps can become very hot and may be a fire hazard.
• 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 in 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 tool is connected to a GFCI.
• Do not clean tools with flammable or toxic solvents.
• Do not operate tools in an area containing explosive vapours 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 Interupter (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 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.
http://electricalrevision.co.uk <link updated to site home>
From Canada, Calgary
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 mionutes to find the materials but my library is so big and link are in the thousands 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 and find better materials
Ground fault at its worst you have to wait for the commercial to play before the training material
But this is a worse case situation when ground fault operations are destroyed or stolen
Ground Fault Causes Electrical Fire - Video
http://wmmic.com <link updated to site home>
<link no longer exists - removed>
http://elcosh.org <link updated to site home>
http://miningquiz.com <link updated to site home>
Pending where you live on the globe here is a great article on grounding and wiring
Groundloop information pages
Why grounding is used ?
Terminology
In Britain, people have 'earth' and in Northern America they have 'ground'. They are exactly th esame thing, only different terms are used in different countries.
Purposes of Grounding
Grounding system has three main purposes:
Overvoltage protection
Lightning, line surges or unintentional contact with higher voltage lines can cause dangerously high voltages to the electrical distribution system wires. Grounding provides an alternative path around the electrical system of your home or workplace minimizes damage from such occurances.
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 deistirution systems as a nearly universal standard for all electric systems.
Current path in order to facilitate the operation of overcurrent devices
This purpose of grounding is the most important one to understand. Grounding system provides certain level of safety to humans and property in case of equipment damages.
Grounding operation in electrical distribution network
The main reason why grounding is used in electrical distribution network is the safety: when all metallic parts in electrical equipments are grounded then if the insulation inside the equipments fails there are no dangerous voltages present in the equipment case. Then the live wire touches the grounded case then the circuit is effectively shorted and fuse will immediatly blow. When the fuse is blown then the dangerous voltages are away.
The safety is the primary function of grounding. Grounding systems are designed so that they do provide the necessary safety functions. Grounding also have other functions in some applications but the safety should not be compromised in any case. Grounding is quite often used to provide common ground reference potential for all equipments but the existing building grounding systems might not provide good enough ground potential for all equipments which might lead to ground potential difference and ground loop problems which are 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 which 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 green wire with yellow stripe. Neutral wire is blue. Live wire in Brown (additional colors for the live wires used in 3 phase systems are black and black with 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 (bacause the current flowing in wire causes voltage drop because wire resistance). This is why a common wire which works as neutral and grounding wire is very bad thing.
When there is separate wiring for grounding you can't still completely avoid the current flowing in grounding wires ! There will always be some capacitive leakage current form 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 leakege current there is always some current flowing in the ground wire and the ground potentials of different electrical power outlets are never equal.
The leakege current can also cause other type of problems. In some situations there are ground fault detect interrupter (GFCI) circuits in use the leakage current caused by many equipments together can make the GFCI to cut the current. Typically GFCI circuits are designed to cut current when there is 30 mA or more difference in currents flowing in live and neutral wires (the difference of those current must flow to ground). Some GFCI circuit can cut the mains feed even at 15 mA leakage current which may mean that if you connect many computer equipments (each of them having 0.5 to 2 mA of leakage) to GFCI protected power outlet you can cause the GFCI to cut the power feed.
Ground wire resistance
In europe it is not important how much 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 then 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 thru 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 make sure that there is never dangrous voltage present in the case. For example in Finland the grounding resistance for medical room outles must be less than 0.2 ohms to be considered safe.
The above is the objective, and all the crap around it is just to make it difficult. Ground means something connected to the surrounding and it must be less then 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.google.ca/url?sa=t&source...zTDLP6QEJoC4yg
http://www.google.ca/url?sa=t&source...iLXp4np-5eI8vQ
http://www.google.ca/url?sa=t&source...l4NMSqsGUJe-eA
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 mionutes to find the materials but my library is so big and link are in the thousands 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 and find better materials
Ground fault at its worst you have to wait for the commercial to play before the training material
But this is a worse case situation when ground fault operations are destroyed or stolen
Ground Fault Causes Electrical Fire - Video
http://wmmic.com <link updated to site home>
<link no longer exists - removed>
http://elcosh.org <link updated to site home>
http://miningquiz.com <link updated to site home>
Pending where you live on the globe here is a great article on grounding and wiring
Groundloop information pages
Why grounding is used ?
Terminology
In Britain, people have 'earth' and in Northern America they have 'ground'. They are exactly th esame thing, only different terms are used in different countries.
Purposes of Grounding
Grounding system has three main purposes:
Overvoltage protection
Lightning, line surges or unintentional contact with higher voltage lines can cause dangerously high voltages to the electrical distribution system wires. Grounding provides an alternative path around the electrical system of your home or workplace minimizes damage from such occurances.
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 deistirution systems as a nearly universal standard for all electric systems.
Current path in order to facilitate the operation of overcurrent devices
This purpose of grounding is the most important one to understand. Grounding system provides certain level of safety to humans and property in case of equipment damages.
Grounding operation in electrical distribution network
The main reason why grounding is used in electrical distribution network is the safety: when all metallic parts in electrical equipments are grounded then if the insulation inside the equipments fails there are no dangerous voltages present in the equipment case. Then the live wire touches the grounded case then the circuit is effectively shorted and fuse will immediatly blow. When the fuse is blown then the dangerous voltages are away.
The safety is the primary function of grounding. Grounding systems are designed so that they do provide the necessary safety functions. Grounding also have other functions in some applications but the safety should not be compromised in any case. Grounding is quite often used to provide common ground reference potential for all equipments but the existing building grounding systems might not provide good enough ground potential for all equipments which might lead to ground potential difference and ground loop problems which are 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 which 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 green wire with yellow stripe. Neutral wire is blue. Live wire in Brown (additional colors for the live wires used in 3 phase systems are black and black with 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 (bacause the current flowing in wire causes voltage drop because wire resistance). This is why a common wire which works as neutral and grounding wire is very bad thing.
When there is separate wiring for grounding you can't still completely avoid the current flowing in grounding wires ! There will always be some capacitive leakage current form 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 leakege current there is always some current flowing in the ground wire and the ground potentials of different electrical power outlets are never equal.
The leakege current can also cause other type of problems. In some situations there are ground fault detect interrupter (GFCI) circuits in use the leakage current caused by many equipments together can make the GFCI to cut the current. Typically GFCI circuits are designed to cut current when there is 30 mA or more difference in currents flowing in live and neutral wires (the difference of those current must flow to ground). Some GFCI circuit can cut the mains feed even at 15 mA leakage current which may mean that if you connect many computer equipments (each of them having 0.5 to 2 mA of leakage) to GFCI protected power outlet you can cause the GFCI to cut the power feed.
Ground wire resistance
In europe it is not important how much 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 then 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 thru 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 make sure that there is never dangrous voltage present in the case. For example in Finland the grounding resistance for medical room outles must be less than 0.2 ohms to be considered safe.
The above is the objective, and all the crap around it is just to make it difficult. Ground means something connected to the surrounding and it must be less then 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.google.ca/url?sa=t&source...zTDLP6QEJoC4yg
http://www.google.ca/url?sa=t&source...iLXp4np-5eI8vQ
http://www.google.ca/url?sa=t&source...l4NMSqsGUJe-eA
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 welocome 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
Second count in management operations and yes it takes time to train but some how 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
Second count in management operations and yes it takes time to train but some how 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 its hard sometimes to sit in a 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 on doing the risk assessment on the safety risks to workers and injuries
Construction Solutions
I know us long winded Canadian boys always want people to live long lives and stay safe and injury free
Silly Canokes
From Canada, Calgary
Well here is a site that does it for you
Do the risk assessment
These guys and gals are great on doing the risk assessment on the safety risks to workers and injuries
Construction Solutions
I know us long winded Canadian boys always want people to live long lives and stay safe and injury free
Silly Canokes
From Canada, Calgary
Dear Penney,
I must apperciate your sharing mentality. Just now i was reading/seen your PPT"s its all really horrible to us/me i am sure if i prepare by own surely atleast its take 20 days but i got this all in a hour.
Even lot of our guys specially EHS proffosionals not ready to share his expertise with by words (even my close friends/seniors also) but u are............... "no words to say'.
But your really great we need your contribution forever. . .Please keep on guide/advise us/me. . .
Always share your expertise with us. . .
From United States, Fpo
I must apperciate your sharing mentality. Just now i was reading/seen your PPT"s its all really horrible to us/me i am sure if i prepare by own surely atleast its take 20 days but i got this all in a hour.
Even lot of our guys specially EHS proffosionals not ready to share his expertise with by words (even my close friends/seniors also) but u are............... "no words to say'.
But your really great we need your contribution forever. . .Please keep on guide/advise us/me. . .
Always share your expertise with us. . .
From United States, Fpo
It no surprise to any of you that I am a former Police Officer turned safety professional. Ive 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 death
Are you the last words in a death sentence?
YouTube - AT&T Don't Text While Driving Documentary
From Canada, Calgary
Think really hard about the attached video and message
Are you the cause of someone death
Are you the last words in a death sentence?
YouTube - AT&T Don't Text While Driving Documentary
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
Find answers from people who have previously dealt with business and work issues similar to yours - Please Register and Log In to CiteHR and post your query.
10 Steps to Safety Excellence Part 1.pptx
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