Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 09-16-2007, 11:19 AM   #31
Electrician philosopher
 
Join Date: Aug 2007
Location: Lilburn, GA
Posts: 838
Share |
Default

adding a ground to an ungrounded recepticle


Or pick up a copy of Mike Holt's "Grounding and Bonding". Education is a beautiful thing.

Andy in ATL is offline   Reply With Quote
Old 09-16-2007, 11:47 AM   #32
Once fried, twice shy.
 
elkangorito's Avatar
 
Join Date: Sep 2007
Location: Thailand
Posts: 251
Default

adding a ground to an ungrounded recepticle


Quote:
Originally Posted by Stubbie View Post
Ok I read through it and find it very similar to the US. I have to admit I had to blow the dust of my metric conversion chart to get a grasp of the sizes of your earthing electrodes outside the simple stuff like 16mm. this is the standard size for our rod electrodes. I did notice for a horizontal installation they require the rod to be 3 meters in length, thats a bit over half meter longer than our code requires for the same. We can however install above code and bury or drive longer ones or more than required. It just isn't very practical. As you have to make your own if going longer than 10 feet. A 10 foot rod is available but uncommon in residential applications.

Anyway thanks for the stuff on the way you earth..

It may interest you that I see you have jumped to using the term earthing where it differentiates from grounding. The NEC is finally going to do the same in 2008 after confusing the heck out of us for years

Stubbie
Thanks for your time & patience Stubbie . I too am not here to proclaim the superiorities or inferiorities of either countrys' electrical codes. I am more concerned with the technical application of certain systems.

Ok...now that I think I have digested what is going on, am I correct in understanding that upon the installation of an earthing system, the installer (electrician) must designate what shall be used as a part of the earthing system? If so, do the designated systems have to be tested to ensure correct electrical operation, before being used? It is my understanding that water pipe cannot be used unless it is a proven part of the earthing system?

In any case, it would not be my choice to use anything other than an installed earthing system (earth cabling/wiring) to facilitate a good earth to any device/appliance.

Thanks again for your understanding.

EDIT: I did notice something in NEC about not using rebar as part of the earthing system if the connection to the system is not accessible (covered in concrete). Many Thai electricians currently use this method, which is outlawed in Thailand.

Also, Thailand has a shocking (literally) electrical system. It uses the TT distribution system (same as Australia) but most Thai electricians seem to continue to do things according to some old (or outdated) US method/code. I am in no way suggesting that the US method is faulty but I am suggesting that mixing 2 different codes/systems is dangerous. The current Thai system is in no way similar to the US system whereas it may have been similar many years ago.
__________________
Switchboard design engineer & Licensed Electrician (Australia).

Last edited by elkangorito; 09-16-2007 at 11:56 AM.
elkangorito is offline   Reply With Quote
Old 09-16-2007, 12:57 PM   #33
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 4,876
Default

adding a ground to an ungrounded recepticle


Quote:
Thanks for your time & patience Stubbie . I too am not here to proclaim the superiorities or inferiorities of either countrys' electrical codes. I am more concerned with the technical application of certain systems.
The same back at you. I think we are going to get along just fine.

Quote:
Ok...now that I think I have digested what is going on, am I correct in understanding that upon the installation of an earthing system, the installer (electrician) must designate what shall be used as a part of the earthing system? If so, do the designated systems have to be tested to ensure correct electrical operation, before being used? It is my understanding that water pipe cannot be used unless it is a proven part of the earthing system?
Our code requires any qualifying electrode that is present at the time of construction to be utilized and bonded to the grounded conductor of the service. In a single family dwelling if a cooper water pipe is present and meets the requirements for an electrode it must be used as an electrode and then must be supplemented with a ground rod (s). Yes we do test but we do not test the water pipe... it is considered a proven electrode and one that would be used regardless. We test the ground rods and other electrodes for 25 ohms or less if a rod does not test then you must drive two of them and bond back to the neutral bar of main service disconnect. Two supplemental rods are all that is required along with the metal water pipe for single family dwellings.



Quote:
In any case, it would not be my choice to use anything other than an installed earthing system (earth cabling/wiring) to facilitate a good earth to any device/appliance.
I absolutely agree with this logic. And would do so myself. Sometimes because of the difficulty of installation in a finished home or cost considerations of homeowners we use 250.130(c) and the 5 options presented there. It doesn't work out very often though as running a new circuit most of the time is easier.

Quote:
I did notice something in NEC about not using rebar as part of the earthing system if the connection to the system is not accessible (covered in concrete). Many Thai electricians currently use this method, which is outlawed in Thailand.
Yes you cannot just hook to rebar if it is exposed or unexposed it must be considered a ufer installed by the builder as a required electrode. Many areas are now requiring ufers to be present at new construction sites. My understanding is that research is showing this to be a most effective earthing means. Google ufer and you will get tons of information if you don't already know this stuff.

Quote:
Also, Thailand has a shocking (literally) electrical system. It uses the TT distribution system (same as Australia) but most Thai electricians seem to continue to do things according to some old (or outdated) US method/code. I am in no way suggesting that the US method is faulty but I am suggesting that mixing 2 different codes/systems is dangerous. The current Thai system is in no way similar to the US system whereas it may have been similar many years ago.
You know I've read about that and maybe have it in my file documents or bookmarks. I'll see if I can find it, my memory aint too good anymore. Hey let me tell you we are not perfect in the USA we tend to think we have the best electrical system. Matter of pride I guess. Nothing wrong with that other than it makes you a little closed minded. I opened mine years ago and realized that there are other people on the planet that are just as competent and you better pay attention to them....they just might teach you something new.

Stubbie

Last edited by Stubbie; 09-16-2007 at 01:14 PM.
Stubbie is offline   Reply With Quote
Old 09-16-2007, 01:04 PM   #34
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 4,876
Default

adding a ground to an ungrounded recepticle


Quote:
buffalo stated....The NEC requires that any equipment used in an electrical circuit be listed for the purpose it is used. water pipes are not listed to carry fault currents, nor any other currents.
It does not... please refer to your code book a little closer.

If they cant carry fault current then why the heck are they required to be bonded?

Stubbie
Stubbie is offline   Reply With Quote
Old 09-16-2007, 01:24 PM   #35
Once fried, twice shy.
 
elkangorito's Avatar
 
Join Date: Sep 2007
Location: Thailand
Posts: 251
Default

adding a ground to an ungrounded recepticle


Thanks Stubbie...I concur completely , although I'm a little dubious about having a minimum 25 Ohm impedance to earth. Australian regs require that the 'earthing circuit' to the electrode must be less than 0.5 Ohms as measured from the furthest point in the earthing circuit. Also, it appears that the US system overcomes the issue of equipotential bonding because the regs require that all 'required' metallic parts be earthed (ie part of the earthing system). This is where the US & Australian regs vary.

Nonetheless, great discussion...I'm learning something new .

Now perhaps we can back to solving the OPs' originally problem using definitive answers as opposed to 'code quoting' & other speculative views.
__________________
Switchboard design engineer & Licensed Electrician (Australia).

Last edited by elkangorito; 09-16-2007 at 01:26 PM.
elkangorito is offline   Reply With Quote
Old 09-16-2007, 01:53 PM   #36
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 4,876
Default

adding a ground to an ungrounded recepticle


Quote:
I concur completely , although I'm a little dubious about having a minimum 25 Ohm impedance to earth. Australian regs require that the 'earthing circuit' to the electrode must be less than 0.5 Ohms as measured from the furthest point in the earthing circuit. Also, it appears that the US system overcomes the issue of equipotential bonding because the regs require that all 'required' metallic parts be earthed (ie part of the earthing system). This is where the US & Australian regs vary.
Yes I noticed that .5 ohm requirement and meant to mention it earlier. I'm guessing (WAG)---wild ass guess.... that soil conditions may differ considerably here compared to the land down under. Also we do not consider earthing as with grounding electrodes as a fault path for opening our overcurent devices (OCPD).... only the return path to the source is considered a low enough impedance to facilitate current flow large enough to trip a protective device. Lightning and utility power surges are the primary reasons we install the earthing electrodes. the thinking behind this is that anything under 600 volts will not move current to earth in sufficient amps for human safety purposes. But lightning will certainly do so and my guess is because of this earthing electrodes for dwellings are for property protection more so than human safety and 25 ohms or less is considered good enough for these high voltage events to move the massive currents involved into the dirt.

I think we have frightened the op to a way off place.......

Stubbie

Last edited by Stubbie; 09-16-2007 at 02:01 PM.
Stubbie is offline   Reply With Quote
Old 09-16-2007, 03:43 PM   #37
Electrician philosopher
 
Join Date: Aug 2007
Location: Lilburn, GA
Posts: 838
Default

adding a ground to an ungrounded recepticle


Actually, you don't even have to get tothe 25 ohms mark. You simply have to add the additional ground rod an call it good.
Andy in ATL is offline   Reply With Quote
Old 09-16-2007, 04:11 PM   #38
Member
 
Join Date: Sep 2007
Posts: 50
Default

adding a ground to an ungrounded recepticle


andy writes..."Because i'm pretty sure that all that rebar ain't listed."

A real electrician knows that when grounding rebar one is providing a listed ground path in case the rebar becomes ACCIDENTLY energized.
buffalonymann is offline   Reply With Quote
Old 09-16-2007, 04:15 PM   #39
Member
 
Join Date: Sep 2007
Posts: 50
Default

adding a ground to an ungrounded recepticle


stubbie writes....If they cant carry fault current then why the heck are they required to be bonded?

Same reason all conductive materials are required to be bonded to the grounding conductor, in case of accidentally becoming energized
buffalonymann is offline   Reply With Quote
Old 09-16-2007, 04:24 PM   #40
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 4,876
Default

adding a ground to an ungrounded recepticle


I give up you are now on my ignore list.

BTW your not grounding rebar it is the electrode.


Stubbie

Last edited by Stubbie; 09-16-2007 at 04:27 PM.
Stubbie is offline   Reply With Quote
Old 09-16-2007, 04:40 PM   #41
Licensed Electrical Cont.
 
Speedy Petey's Avatar
 
Join Date: Feb 2004
Location: NY State
Posts: 6,784
Default

adding a ground to an ungrounded recepticle


Quote:
Originally Posted by buffalonymann View Post
A real electrician knows that when grounding rebar one is providing a listed ground path in case the rebar becomes ACCIDENTLY energized.
All I can say about this is:HAHAHAHAHAHAHAHAHAHA

Thank you sir troll. THAT right there was FUNNY!
__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC.
Speedy Petey is online now   Reply With Quote
Old 09-16-2007, 04:56 PM   #42
Electrician philosopher
 
Join Date: Aug 2007
Location: Lilburn, GA
Posts: 838
Default

adding a ground to an ungrounded recepticle


The rebar is the electrode!!! But then again YOU are the master electrician from NY state. Do you even own a code book? Please refer to 250.52(3). I'm guessin you are wanting the steel wire that ties the rebar together to be listed also?

Andy in ATL is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
This doesnt seem right. JoulesWinfield Electrical 27 07-26-2009 07:40 PM
Hot Tub Install--Grounding Rod Question statgeek_rob Electrical 16 09-15-2007 02:59 AM
Replacing wiring in middle of run, ungrounded lighting circuit alexz Electrical 3 07-05-2007 08:53 PM
Subpanel feeder questions Silhanek Electrical 4 03-22-2007 06:30 PM
Adding a ground bar Chemgeek Electrical 1 02-18-2007 12:28 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.