Need secondary ground w/ UFER ???
- Thread starter eagle
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- Bremerton, Washington
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- Master Electrician
Re: Need secondary ground w/ UFER ???
I didn't understand it either when I first instruced a grounding class. What, no ground rods with a Ufer (or concrete encased electrode)?
Ground rods are only required to supplement a metal underground water line (metal today-plastic tommorrow).
In new construction,most water lines are plastic, so the water line does not qualify as a grounding electrode.
But you are correct you still need to bond to the metal water lines in the building, per 250.104. This connection can be made anywhere in the building as long as its accessible.
I didn't understand it either when I first instruced a grounding class. What, no ground rods with a Ufer (or concrete encased electrode)?
Ground rods are only required to supplement a metal underground water line (metal today-plastic tommorrow).
In new construction,most water lines are plastic, so the water line does not qualify as a grounding electrode.
But you are correct you still need to bond to the metal water lines in the building, per 250.104. This connection can be made anywhere in the building as long as its accessible.
A
a.wayne3@verizon.net
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Re: Need secondary ground w/ UFER ???
Ever se a ufer fail ????I have
Ever se a ufer fail ????I have
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Need secondary ground w/ UFER ???
This does seem strange as any grounding electrode can fail. There is many reasons for failure too but As Tom has said the NEC does not require a Supplemental Electrode unless there is a water pipe that qualifiy's for a electrode "available on the premises at each building or structure served" It also requires that we use it if available. so we have no choice not to. this is also a requirement for UFER's too, as well as any item in 250.52(A)(1) through (A)(6) Which covers every possible electrode. so if they exist then they have to be used. But how many don't use the re-bar in the footings or are not at the site in-time when they are poured? so how are we supposed to connect to something buried in concrete? If we have more than one which one is the primary electrode and which one will be the Supplemental Electrode? or are they all just bonded together to form one electrode and would follow under the main electrode requirements?
I noticed that they didn't include 250.52(A) (7) in this which would have us using tanks or old wells and other types of metal under ground. which to me could be very good electrodes.
Of course they could be concerned that these could be removed at a later time so they would not be dependable
[ December 27, 2003, 03:24 AM: Message edited by: hurk27 ]
This does seem strange as any grounding electrode can fail. There is many reasons for failure too but As Tom has said the NEC does not require a Supplemental Electrode unless there is a water pipe that qualifiy's for a electrode "available on the premises at each building or structure served" It also requires that we use it if available. so we have no choice not to. this is also a requirement for UFER's too, as well as any item in 250.52(A)(1) through (A)(6) Which covers every possible electrode. so if they exist then they have to be used. But how many don't use the re-bar in the footings or are not at the site in-time when they are poured? so how are we supposed to connect to something buried in concrete? If we have more than one which one is the primary electrode and which one will be the Supplemental Electrode? or are they all just bonded together to form one electrode and would follow under the main electrode requirements?
I noticed that they didn't include 250.52(A) (7) in this which would have us using tanks or old wells and other types of metal under ground. which to me could be very good electrodes.
Of course they could be concerned that these could be removed at a later time so they would not be dependable
[ December 27, 2003, 03:24 AM: Message edited by: hurk27 ]
A
a.wayne3@verizon.net
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Re: Need secondary ground w/ UFER ???
Just had to add that question,why??/ because i hot checked a home the other day.Off the 50 amp breaker I used the 2 hot phases and the ground.What happened was as i hot checked the system went a little crazy.....Turn on a light at the entry and the dining light came on,As It turned out the t pole didn`t have a bond screw installed so there was no neutral.the ufer was tight and had been inspected so why ???? Where was the neutral ???? any ideas....
Just had to add that question,why??/ because i hot checked a home the other day.Off the 50 amp breaker I used the 2 hot phases and the ground.What happened was as i hot checked the system went a little crazy.....Turn on a light at the entry and the dining light came on,As It turned out the t pole didn`t have a bond screw installed so there was no neutral.the ufer was tight and had been inspected so why ???? Where was the neutral ???? any ideas....
- Location
- Illinois
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- retired electrician
Re: Need secondary ground w/ UFER ???
a.wayne,
I don't understand your last post. The grounding electrode system and the bonding screw have nothing to do with an open neutral. The grounding and bonding will not make up for an open neutral.
Don
a.wayne,
I don't understand your last post. The grounding electrode system and the bonding screw have nothing to do with an open neutral. The grounding and bonding will not make up for an open neutral.
Don
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Need secondary ground w/ UFER ???
Allen
What I'm getting is at the temp pole there was no bond between the neutral and grounding (no bond screw) and when you did a temp supply to the house panel you pulled power off the temp pole grounding instead of the neutral? If this was the case the only connection for the return path to the transformer would be through the electrods. this would account for the circuits acting like you had a loss neutral. Even a ufer would not be enough to allow for a lost neutral as the resistance on the ufer can be too high also.
Is this what your saying or I'm I spitting into the wind.
Allen
What I'm getting is at the temp pole there was no bond between the neutral and grounding (no bond screw) and when you did a temp supply to the house panel you pulled power off the temp pole grounding instead of the neutral? If this was the case the only connection for the return path to the transformer would be through the electrods. this would account for the circuits acting like you had a loss neutral. Even a ufer would not be enough to allow for a lost neutral as the resistance on the ufer can be too high also.
Is this what your saying or I'm I spitting into the wind.
jimwalker
Senior Member
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- TAMPA FLORIDA
Re: Need secondary ground w/ UFER ???
Allen how did this pole slip past TECO.They usually do a good inspection.Yes if the screw was missing i see the problem.Any time i jump from a T to the house i turn all breakers off first ,then check with digital to see that it is balanced , but this might not be good enough as the ground might just give me a false reading with no load.
Allen how did this pole slip past TECO.They usually do a good inspection.Yes if the screw was missing i see the problem.Any time i jump from a T to the house i turn all breakers off first ,then check with digital to see that it is balanced , but this might not be good enough as the ground might just give me a false reading with no load.
jxofaltrds
Inspector Mike®
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- Mike P. Columbus Ohio
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Re: Need secondary ground w/ UFER ???
Roger
GE makes lightbulbs don't they?
Mike P.
Roger
GE makes lightbulbs don't they?
Mike P.
jimwalker
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- TAMPA FLORIDA
Re: Need secondary ground w/ UFER ???
I'm not suggesting the ground take the place of the neutral.But usually at the T the grd and neutral are bonded together. GREEN SCREW
I'm not suggesting the ground take the place of the neutral.But usually at the T the grd and neutral are bonded together. GREEN SCREW
A
a.wayne3@verizon.net
Guest
Re: Need secondary ground w/ UFER ???
Hurk exactly what i was saying.The t poles with 50 amp gfci breaker.20 amp gfi breaker.not to mention that with these load centers the neutral bar can be accessed by dimantling entire front assembly.The only accesible contact is a little ground bar I didn`t see the green ground screw missing ok my bad but the ufer should have been sufficient for lighting circuits.remember the key to a proper hot check is to turn all switches on and off and leave them off so at no time was there more than a couple of recessed cans on at one time,shouldn`t the grounding system supported this ???
Hurk exactly what i was saying.The t poles with 50 amp gfci breaker.20 amp gfi breaker.not to mention that with these load centers the neutral bar can be accessed by dimantling entire front assembly.The only accesible contact is a little ground bar I didn`t see the green ground screw missing ok my bad but the ufer should have been sufficient for lighting circuits.remember the key to a proper hot check is to turn all switches on and off and leave them off so at no time was there more than a couple of recessed cans on at one time,shouldn`t the grounding system supported this ???
- Location
- Massachusetts
Re: Need secondary ground w/ UFER ???
No the grounding electrodes should not "support that"
What is the resistance of the the earth between the rod at the house and the rod at the pole added to the resistance of the rods?
The grounding electrodes are worthless for this type of use.
No the grounding electrodes should not "support that"
What is the resistance of the the earth between the rod at the house and the rod at the pole added to the resistance of the rods?
The grounding electrodes are worthless for this type of use.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Need secondary ground w/ UFER ???
Not if the earth resistance is to high. remember you are still working against Ohm's law and the resistance of Earth. Just because you have a UFER will not mean the the?true resistance will be low. If this UFER is in a very dry soil the resistance can be very high but the impedance can be low if the frequency of a lightning strike is high. but in no terms should a electrode be used for return current as this will place as high as 120 volts on it and can get someone hurt as all the grounding in a building will be connected to it also and it to will have this voltage on it. so if someone grabs a water pipe they would be in for a shock. I'm sure you know this already. but I'm bringing it up just incase someone else is in here reading this that wouldn't know. Keep in mind what the purpose of the electrode is for and why the NEC does not allow it for fault current path.
I know there are many that belive a UFER is the best electrode but many studys of lightning strikes show that the ring electrodes (Without getting into grid grounds) is better for lightning protection.
Not if the earth resistance is to high. remember you are still working against Ohm's law and the resistance of Earth. Just because you have a UFER will not mean the the?true resistance will be low. If this UFER is in a very dry soil the resistance can be very high but the impedance can be low if the frequency of a lightning strike is high. but in no terms should a electrode be used for return current as this will place as high as 120 volts on it and can get someone hurt as all the grounding in a building will be connected to it also and it to will have this voltage on it. so if someone grabs a water pipe they would be in for a shock. I'm sure you know this already. but I'm bringing it up just incase someone else is in here reading this that wouldn't know. Keep in mind what the purpose of the electrode is for and why the NEC does not allow it for fault current path.
I know there are many that belive a UFER is the best electrode but many studys of lightning strikes show that the ring electrodes (Without getting into grid grounds) is better for lightning protection.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Need secondary ground w/ UFER ???
Dereck I remember digging those rings with the 80' radials with 20' rods every 20' around Tel-co site buildings back a few years ago and we didn't have a trencher ether. At least the grid's wern't as bad as the excavator would use a bulldozer to clear off the area we would layout the grid cad weld the crosses and the rods then they would plow the soil back over the site. Once in a while they would catch the grid but we were right there to fix it. I haven't done that kind of work in years. I heard that we cant use "T" or "X" cad's anymore just parallel cad connectors?
Dereck I remember digging those rings with the 80' radials with 20' rods every 20' around Tel-co site buildings back a few years ago and we didn't have a trencher ether.
At least the grid's wern't as bad as the excavator would use a bulldozer to clear off the area we would layout the grid cad weld the crosses and the rods then they would plow the soil back over the site. Once in a while they would catch the grid but we were right there to fix it. I haven't done that kind of work in years. I heard that we cant use "T" or "X" cad's anymore just parallel cad connectors?- Status