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 08-15-2012, 08:53 AM   #106
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 4,871
Share |
Default

Need Help Understanding Neutal / Ground


Quote:
Originally Posted by gookinp07 View Post
I definitely will. I don't mind killing the disconnect to work in the main panel, but I didn't even want to open that disconnect up to look at it.
I understand that if you don't think it is not bonded to the service neutral. That not being the case the metal enclosure could be energized to as much as 240 volts. Does the disconnect ahead of your main panel have fuses in it or do you know ?

Stubbie is offline   Reply With Quote
Old 08-15-2012, 10:52 AM   #107
Member
 
Join Date: Sep 2011
Location: western Ny
Posts: 1,243
Default

Need Help Understanding Neutal / Ground


Quote:
Originally Posted by stubie View Post
What the graphic is showing is there is no equipment ground in the wiring it is just a hot wire and neutral. The metal pole is only grounded by a ground rod driven into the earth. The hot wire has touched the metal pole energizing it. Though there is a ground rod bonded to the metal light pole .. and brings both to earth potential (zero volts) there is not an equipment ground in the wiring bonded to the metal light pole an thus no effective ground fault path back to the transformer. Earth is the only path that is available for the fault current to return to the source transformer center tap. Earth resistance is so high it will not allow enough current to flow in the hot wire to trip the breaker. So lets say the earth resistance is only allowing 5 amps to flow into the earth. This will not trip even a 15 amp breaker. When you touch the energized pole (no breaker has tripped) you provide a parallel path for current to earth at some potential greater than zero. In this case 90 volts and you get electrocuted. Remember current will take all paths available to it to get back to its source. However if we give it a low impedance/resistance path back to the transfomer like copper wire nearly all the current take that path. In the graphic the only path is high resistance dirt.
Several yeares ago I had to teach this to my brother who also thought all ground faults cleared thru the ground rod. I still don't think he gets it but none the less I showed him this experiment. I drove a new ground rod outside my home as I wanted to add a second one to update. Anyway, before I connected it to the ground system I hooked a #12 wire to it and connected it to a 20 amp breaker in my panel. I then asked him what would happen when I turned it on. He said" it will trip the breaker". I turned it on and it held. I put my clamp-on amp meter on it and read around 12 amps.
danpik is offline   Reply With Quote
The Following 2 Users Say Thank You to danpik For This Useful Post:
mpoulton (08-15-2012), roofnron (08-16-2012)
Old 08-15-2012, 11:22 AM   #108
Member
 
Join Date: Feb 2012
Location: Kansas
Posts: 81
Default

Need Help Understanding Neutal / Ground


Quote:
Originally Posted by danpik View Post
Several yeares ago I had to teach this to my brother who also thought all ground faults cleared thru the ground rod. I still don't think he gets it but none the less I showed him this experiment. I drove a new ground rod outside my home as I wanted to add a second one to update. Anyway, before I connected it to the ground system I hooked a #12 wire to it and connected it to a 20 amp breaker in my panel. I then asked him what would happen when I turned it on. He said" it will trip the breaker". I turned it on and it held. I put my clamp-on amp meter on it and read around 12 amps.
I have had that same argument with the safety director here. I need to do this experiment for him.
M Engineer is offline   Reply With Quote
Old 08-16-2012, 09:55 PM   #109
Member
 
Join Date: Dec 2011
Location: Catawba, VA
Posts: 68
Default

Need Help Understanding Neutal / Ground


Quote:
Originally Posted by gookinp07 View Post
There are only 3 wires with no metal conduit going from the disconnect to the house panel. The ground is bonded to the neutral at the house panel AFTER the disconnect. Should they be bonded AT the disconnect? Does it matter?
Do you have a ground wire also running out of your meter base? Potentially you are bonded to the neutral there?
roofnron is offline   Reply With Quote
Old 08-16-2012, 10:10 PM   #110
Member
 
Join Date: Aug 2012
Posts: 49
Default

Need Help Understanding Neutal / Ground


Quote:
Originally Posted by roofnron View Post
Do you have a ground wire also running out of your meter base? Potentially you are bonded to the neutral there?
Just checked. The meter has no bonding to the ground. The wires come in from overhead, go into the meter, then come out overhead into the top of the basement.

On another note, my house has 2 ground rods. One is bound with the neutral inside the main panel. The other ground rod is attached to the copper plumbing system throughout the house. I also noticed that a ground wire from a junction box is bound to the copper plumbing system as well. Is this correct? Should the copper pipe system be bound with the neutral/ground?
gookinp07 is offline   Reply With Quote
Old 08-16-2012, 10:27 PM   #111
Member
 
Join Date: Aug 2012
Posts: 46
Default

Need Help Understanding Neutal / Ground


Danpik....I totally believe and agree.....(ignoring the same test performed during a heavy rain)

I would be tempted to try that with my house....I have an Ufer ground.....along with a ground rod at the front of the house bonded to the plumbing....#4 wire from there to another ground rod next to my slab (ufer)...along with the #4 wire running along the footing of my slab...bonded to the rebar...and then terminated in my load center.

Even with that Ufer ground....I bet I could shove a hot into the ground a foot from my slab and I would not be surprised if it did not trip the breaker......
jeepdawg is offline   Reply With Quote
Old 08-16-2012, 11:26 PM   #112
UAW SKILLED TRADES
 
Stubbie's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 4,871
Default

Need Help Understanding Neutal / Ground


Quote:
Originally Posted by gookinp07 View Post
Just checked. The meter has no bonding to the ground. The wires come in from overhead, go into the meter, then come out overhead into the top of the basement.

On another note, my house has 2 ground rods. One is bound with the neutral inside the main panel. The other ground rod is attached to the copper plumbing system throughout the house. I also noticed that a ground wire from a junction box is bound to the copper plumbing system as well. Is this correct? Should the copper pipe system be bound with the neutral/ground?
If your copper water pipe is in in contact with the earth (dirt) for 10 feet after it leaves the house then it is required to be bonded to the service neutral at the service equipment. Remember these are grounding electrodes not current paths for fault current or neutral current. This earth grounding is for lightning strikes, stabilizing voltage and power surges from the utiltity.

The ground wire coming from a junction box is questionable ...
Stubbie is offline   Reply With Quote
Old 08-16-2012, 11:41 PM   #113
Member
 
Join Date: Aug 2012
Posts: 49
Default

Need Help Understanding Neutal / Ground


Quote:
Originally Posted by stubie View Post
If your copper water pipe is in in contact with the earth (dirt) for 10 feet after it leaves the house then it is required to be bonded to the service neutral at the service equipment. Remember these are grounding electrodes not current paths for fault current or neutral current. This earth grounding is for lightning strikes, stabilizing voltage and power surges from the utiltity.

The ground wire coming from a junction box is questionable ...
The copper pipes never go underground or even leave the interior of the house. Is the copper pipe system being needlessly electrified? Should the ground wire coming out of the junction box be removed? I just traced as much of the pipe system as I could and I didn't see any more wires attached to it.

This house was built in the 40s or 50s and was rewired in the 80s I believe. There seems to have been some questionable choices made when rewiring.
gookinp07 is offline   Reply With Quote
Old 08-17-2012, 05:27 AM   #114
Member
 
Join Date: Nov 2011
Location: Md/Pa
Posts: 942
Default

Need Help Understanding Neutal / Ground


Quote:
Originally Posted by gookinp07 View Post
Just checked. The meter has no bonding to the ground. The wires come in from overhead, go into the meter, then come out overhead into the top of the basement.

On another note, my house has 2 ground rods. One is bound with the neutral inside the main panel. The other ground rod is attached to the copper plumbing system throughout the house. I also noticed that a ground wire from a junction box is bound to the copper plumbing system as well. Is this correct? Should the copper pipe system be bound with the neutral/ground?
Yes, the pipes should be bonded with the neutral for your safety. Could there be a buried wire outside between the 2 ground electrodes? Other than the junction box, which is questionable like Stubbie said, I'm not seeing a bond from the pipes to your neutral.
zappa is offline   Reply With Quote
Old 08-17-2012, 06:05 AM   #115
Member
 
Join Date: Sep 2011
Location: western Ny
Posts: 1,243
Default

Need Help Understanding Neutal / Ground


Quote:
Originally Posted by zappa View Post
Yes, the pipes should be bonded with the neutral for your safety. Could there be a buried wire outside between the 2 ground electrodes? Other than the junction box, which is questionable like Stubbie said, I'm not seeing a bond from the pipes to your neutral.
There should also be a bonding jumper at the water meter if you have one. A couple years ago my local water authority was doing a city wide water meter upgrade and one of the installers is lucky to be alive. He pulled a meter that did not have one and as soon as he broke the connection he got knocked on his butt with some pretty good burns on his hands. Wound up in the hospital to get his heart checked out as he took a pretty good shot thru it (one hand to the other). The city and the company doing the work instituted a new policy that required a jumper cable be temporarily clamped on by the installer to bond the connection when changing these out. They were also required to leave a document explaining to the homeowner of the situation and the method to have it corrected.
danpik is offline   Reply With Quote
The Following User Says Thank You to danpik For This Useful Post:
zappa (08-17-2012)
Old 08-17-2012, 11:23 AM   #116
Member
 
Join Date: Aug 2012
Posts: 49
Default

Need Help Understanding Neutal / Ground


I actually have well water. There is a plastic water pipe running from the well to the basement. I'm pretty confident that the copper pipe system never leaves the house or even goes underground. It definitely doesn't do so in the basement. The only thing of note connected to the copper pipes is an oil-powered water heater that we don't run until it's winter time. We have a hot water baseboard heating solution. For the summer we have an electric hot water heater that's connected to the copper pipes via pvc pipe. As for the ground rods being connected, I seriously doubt that. The ground rods are pretty far apart and around the corner of the house.

gookinp07 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
Attic wiring - ceiling lighting uses 14/2 cable without ground darlingm Electrical 3 11-29-2011 09:01 AM
Ground rod and ground wire question mulltron Electrical 17 07-29-2011 05:10 PM
To ground or not to ground Red Squirrel Electrical 2 10-14-2010 08:42 PM
Wiring an outlet using both ground screws instead of pig-tailing together. cabber24 Electrical 5 08-26-2010 08:40 AM
Electrical Ground Problem cabinetman Electrical 15 01-28-2010 04:55 PM




Top of Page | View New Posts

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