Code in your area? "grounds"

[brightidea]

Is it now a requirement in your area to pull separate grounding conductors through all conduits, including rigid metal pipe, IMC, EMT, and ofcourse PVC.

How about metalic sheathed cables, do they require bonding bushings with attached lugs to conect and bond the sheath of the cable with the rest of an installation? If so at both ends?

Most installations that use metalic conduits have no ground wire pulled through, since metal is a good conductor and could be used as the grounding conductor. Today, practices are changing and much work is being done with a seperate grounding conductor pulled in addition to the conductive properties of the conduits being used as mechanical protection.

What is the practice that are being used in your area, and what is required by code?

Grounding theory often confuses me, in regards to safety purposes, for it is supposed to provide protection from personal injury and damage to property.
But when you get into fault currents, which can be a much higher magnitude of the regular circuit conductors capacity, it is almost impracticable to size grounds to safely handle such currents.

It is undertstood that overcurrent protection, such as fuses and breakers help with this issue, but when is it determined safe enough?

Under a specific ammount of time.
Ive been shocked before multible times but never carried a full fault current through my body that I know of.

What is would be the effect of a person being in contact of a grounding wire during a fault?

 

[don_resqcapt19]

What is would be the effect of a person being in contact of a grounding wire during a fault?

If the grounding wire that the person is touching is the one that is carrying the fault current, he will be subjected to a voltage to earth that is equal to the voltage drop on the EGC. Under fault conditions, this voltage may often be greater than 40 volts. If he is touching a grounding conductor that is not the one clearing the fault, he will be subjected to a voltage that is equal to the votlage drop on the grounded conductor between the main bonding jumper and XO of the utility transformer. This votlage drop should be much less than that on the EGC itself. Note that this second voltage will be on all conductive objects that are connected to the electrical grounding system. These voltages will be there until the OCPD acts to open the circuit.
Don

 

[don_resqcapt19]

But when you get into fault currents, which can be a much higher magnitude of the regular circuit conductors capacity, it is almost impracticable to size grounds to safely handle such currents.

Not really. They only have to handle the current for a very short time if the OCPD is doing its job. An insulated copper conductor can handle 1 amp for each 42.25 circular mils of area for 5 seconds. For example #14 has an area of 4110 circular mils and can carry 97.31 amps for 5 seconds. Now 5 seconds is much longer than the trip time of a properly selected OCPD, so we need to convert this to "amperes squared seconds". 97.31 x 97.31 x 5 =47,346 amperes squared seconds. You divide this number by the expected clearing time of the OCPD to find out how much current the conductor can withstand. If the OCPD has a clearing time of 3 cycles (0.05 seconds) than the #14 can withstand 973 amps without damge for 3 cycles. (take the square root of 47346/0.05 to get this number).
This Bussmann document does a much better job of showing this than I did.
Don

 

[George Stolz]

Brightidea, welcome to the forum.

I don't suppose you could fill us in on some of your background? "Electrician" is a broad term. I am a residential electrician who recently broke into commercial. Most of my practical experience is with romex, and for the past two months I've been learning to bend pipe.

Is it now a requirement in your area to pull separate grounding conductors through all conduits, including rigid metal pipe, IMC, EMT...

No, according to 250.118 (2), (3) and (4), IMC, RMC, and EMT are still valid types of equipment grounding conductors. However, a conductor is generally pulled inside these conduits in practice in my area.

How about metalic sheathed cables, do they require bonding bushings with attached lugs to conect and bond the sheath of the cable with the rest of an installation? If so at both ends?

No, according to the UL White Book, page 177 (pdf 215):

Grounding ? Metal-clad cable connectors for use with metal-clad interlocking armor ground cable, corrugated aluminum or copper tube, or smooth aluminum tube, are considered suitable for grounding for use in circuits over and under 250 V and where installed in accordance with ANSI/NFPA 70, ??National Electrical Code.

Also, I don't believe bonding bushings are available for MC connectors, but I could be mistaken. I don't see how you could install one on a regular snap-in 3/8" connector.

 

[charlie b]

Is it now a requirement in your area to pull separate grounding conductors through all conduits, including rigid metal pipe, IMC, EMT, and ofcourse PVC.

I can't answer this question, but I can, I hope, help to explain it. From my years living in Chicago, I recall (and I might be completely wrong about this) that the Chicago Electrical Code includes the requirement that an EGC be pulled, even if the conduit is metallic. I hope someone from that area will affirm or refute that old memory of mine.

Is that what your are asking, about whether other local areas have similar requirements?

 

[brightidea]

A Bright Idea to get advice!

A Bright Idea to get advice!

Hi, I'm BrightIdea,

I thought it would be a bright idea to ask for help and seek advice from more knowledgeable people than myself, and there will be a great many of them out there, this I have no doubt about. Also, if I can offer any in return I wish to contribute too.

If not bright I believe wise. Bright that in doing so we can put some light on the subject.

It has been said before. It is better to be corrected by a wise person than to be praised by a fool. I try to remember this as I live my life and try my best to apply myself in the Electrical trade.

I would like to thank you folks for helping me out to help improve my knowledge and aid in my growth as a practitioner of the best trade there is. Also, thank you for your warm welcome, and please allow me to say how happy I am to join in this wonderful forum. I hope that this place can offer as much interest and pleasure for all that participate.

For your interest, if you are, I would like to introduce myself, even though I?m a bit shy, but I see others here using their real names, so I will as well.

My name is Karel de Koning; I am 28 years old and practicing as an Electrician in Ontario, Canada. Since I was 16 years old I have been involved in studying and applying the electrical trade. At age 21, and after 9000 hours and 5 years of hard work I received my Journeyman Construction Maintenance Electricians license with an Inter-provincial Red seal endorsed standard; allowing me to travel across Canada as an Journeyman. Even though I haven?t worked in the other provinces I do work across my province Ontario, hundreds of kilometers to where the work is. Recently I have returned from a long term trip to China, where I have used some of my Electrician skills too.

Three years ago I obtained my Master Electrician License, which allows me a higher level of responsibility in our field. Even though I am confident in my ability to do excellent work, I still feel inadequate in some ways as a Master Electrician, such as theory, science and even my mathematics. For I only have a high school education, and have focused my energies in the practice of skilled trades rather than in academics. Traditional apprenticeship was my choice as an alternative to college and university.
I
In some ways I feel I should return to school and do more formal training, perhaps an engineering degree program through University, I am interested in many things even beyond Electricity. So I still might consider further studies, even possibly in the arts.

One area that I wish to continue study in is furthering my ability with instrumentation.
I lost out on a job to a college grad once, because he was an instrument tech and I was a trained electrician. The employer hired the school trained techie rather than I. My time in the field then was 10 years. Perhaps, it wasn?t my time; they already had more electricians than they did have techies. I wish him well anyway; he might as well need the work more than I. Since then I always felt I need more to offer my employer.
For myself I continue in trying to learn as much as I can, keep an open mind, and be hard working. Reading is very helpful, and I spend much time doing that as I can, but I must remember that getting clarification and interpreting is so important too.

As an electrician now with 12 official years under my belt, I have worked in a wide variety of settings, from ancient and old work to ultra modern. Done jobbing, service work, from time in split seconds to long term construction and maintenance projects that will continue past my walking years. I?ve worked in residential, shanty town to low cost housing to mansions for society?s elite. I have worked on things that have been built up, fallen down, burnt up and that have been watered down.

I?ve helped build multi story buildings, towers and even subterranean facilities, commercial, retail, office-space, institutions such as churches hospitals and even jails, (sorry no electric chairs) industries small, medium, large and heavy, manufacturing to processing, packaging, shipping and distribution. I have worked in rural applications from wiring a chicken coup to poop, scoop and pump A Military installation earth-quake proof, but really doubt damage due to nuke (sorry against bombs and false flag operations). I?ve hooked up communications, such as radio, computers, telephony, satellites, fiber-optics, light and sound, fire alarms, security to pest control. Power generation, wind, solar, water, fossil and nuclear, power distribution, overhead pole to pole, on the ground, underground, and even under water. Whether on land in land, under land over land, in whatever weather, rain shine sleet or snow, morning noon or night, hot humid dry or cold, I?ve worked in -40 to +40 degrees C,

I have even done work for film and television, but still have not made the big time, or been on the big screen, although I have wired two, I believe I have applied my electrical knowledge for almost any kind of situation on this earth, but not in the outer space, although on an airplane. If I haven?t been involved in such work physically, I have been in my imagination and even in my dreams.

My entire life revolves around electricity; I eat sleep breath and talk electricity.

Please don?t take me the wrong way when I mention such things, I am happy to have such chance. I only mention because someone asked. .

Today, I?m especially pleased to join this forum, and hope that we all can share more.

Thanks once again

What a great opportunity this is we all have here, may you all get the satisfaction you seek here and out there.

God bless,
bright idea

 

[George Stolz]

My entire life revolves around electricity; I eat sleep breath and talk electricity.

Well then, you've come to the right place.

 

[redtail_MH]

Welcome aboard. I joined this forum a couple of months ago, and it has been great.

 

[brightidea]

Again thank you for your replies and most importanlty your help.

bright idea

 

[JohnJ0906]

This is a fantastic tool for all of us to improve our knowledge of our chosen feild. I just joined myself, and have certainly learned a few things! I am always aware that I still have a lot to learn. I hope to improve myself professionally, which would certainly translate to improving myself as a person. I'm certainly going to keep coming back!

 

[tom baker]

BightIdea, you stated that:
Is it now a requirement in your area to pull separate grounding conductors through all conduits, including rigid metal pipe, IMC, EMT, and ofcourse PVC.

You are aware that a EGC is not required for IMC and RMC in the NEC. The IMC and RMC is itself allowed as an EGC. If an EGC is required, then its a workmanship issue on the IMC and RMC installation, per the CMP. I personally want to see an EGC in all raceways.