Foundation earthing not installed

[Gilf]

We have a 14 floor building. Site has started pouring the concrete prior to electrical project being complete and they're up at 8th floor. We've been told that no foundation grounding was installed.
Q1: in this case, is foundation earthing required by the code? I know that this is still considered a new building as per 250.50. I do not feel safe about this anyway, where do I go in the code to prove my point?
Q2: how do we connect to the re-bar of a finished foundation? We had planned using exothermic welds previously.

thanks for helping this newbie!

 

[petersonra]

We have a 14 floor building. Site has started pouring the concrete prior to electrical project being complete and they're up at 8th floor. We've been told that no foundation grounding was installed.
Q1: in this case, is foundation earthing required by the code? I know that this is still considered a new building as per 250.50. I do not feel safe about this anyway, where do I go in the code to prove my point?
Q2: how do we connect to the re-bar of a finished foundation? We had planned using exothermic welds previously.

thanks for helping this newbie!

A!: Not required. If a qualifying grounding electrode is present you have to use it though. There could be various reasons the rebar in the foundation does not qualify as a GE. One could be the use of coated rebar. Another might be the use of plastic sheeting or other nonconductive material under the foundation. Both would disqualify it as a GE.
A2: Welding is one way. Some kind of listed grounding connector is another.

 

[mwm1752]

All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system.
(3) Concrete-Encased Electrode.

You'll get many different views on this one -- not all foundations have steel but if they do they are present IMO -- a GC that is building an 14 story building should know the rules -- there may be a chance the vertical steel is tied to the footer steel (get pics) with tie wires -- if so bond the "UFER" verts to building steel then building steel to MDP -- If not find footer steel tie with 4# cu & patch concrete. many ways to skin this cat -- but IMO UFER is required new install.

 

[petersonra]

[/B]You'll get many different views on this one -- not all foundations have steel but if they do they are present IMO -- a GC that is building an 14 story building should know the rules -- there may be a chance the vertical steel is tied to the footer steel (get pics) with tie wires -- if so bond the "UFER" verts to building steel then building steel to MDP -- If not find footer steel tie with 4# cu & patch concrete. many ways to skin this cat -- but IMO UFER is required new install.

what if it is epoxy coated rebar?

 

[mwm1752]

what if it is epoxy coated rebar?

I get your point -- it would not be considered an electrode ( as it is coated & cannot contact earth & not pertain to electrode codes.) We are going to see fiberglass type rebar being used if the future so that would not qualify also -- But how simple it is to get 20' of min 4# rebar or use CU for the most reliable electrode that exist especially in a large multi use building -- I'd bet there is some steel encasement somewhere with building steel. I would like to think the GC did his job properly & a fair explanation is out there

 

[petersonra]

I get your point -- it would not be considered an electrode ( as it is coated & cannot contact earth & not pertain to electrode codes.) We are going to see fiberglass type rebar being used if the future so that would not qualify also -- But how simple it is to get 20' of min 4# rebar or use CU for the most reliable electrode that exist especially in a large multi use building -- I'd bet there is some steel encasement somewhere with building steel. I would like to think the GC did his job properly & a fair explanation is out there

what difference does it make anyway? if there is no CEE or building structure that qualifies as a GE pound a couple of rods and be done with it.

 

[Gilf]

The site is in Middle East and they seem to have an odd way of doing things. So if I have a ground loop around the building, grounds rods on the loop, ground the water pipes and ground the service entrance I'm actually ok? Of course lps will also connect to the loop.

I also read the standard as ufer must be connected too, so I'm still a little uneasy about it. If I insist to ground the re-bar how would they do it physically? Break concrete, find re-bar and connect copper by weld? Also what would I do about tie wires?

 

[Fulthrotl]

The site is in Middle East and they seem to have an odd way of doing things. So if I have a ground loop around the building, grounds rods on the loop, ground the water pipes and ground the service entrance I'm actually ok? Of course lps will also connect to the loop.

I also read the standard as ufer must be connected too, so I'm still a little uneasy about it. If I insist to ground the re-bar how would they do it physically? Break concrete, find re-bar and connect copper by weld? Also what would I do about tie wires?

a ground loop with rods, tied to cold water, etc. is pretty substantial.
if you bond it to building steel, all should be well..

 

[mwm1752]

what difference does it make anyway? if there is no CEE or building structure that qualifies as a GE pound a couple of rods and be done with it.

the difference to me is the electrode system is important part of the electrical system so using a couple of ground rods (worthless but compliant) compared to a UFER is a big difference.

"if there is no CEE or building structure that qualifies as a GE pound a couple of rods and be done with it." absolutely in fact most likely be required in those conditions though I never had seen a single (or double) ground rod meet the 25 ohm rule.

 

[mwm1752]

The site is in Middle East and they seem to have an odd way of doing things. So if I have a ground loop around the building, grounds rods on the loop, ground the water pipes and ground the service entrance I'm actually ok? Of course lps will also connect to the loop.

I also read the standard as ufer must be connected too, so I'm still a little uneasy about it. If I insist to ground the re-bar how would they do it physically? Break concrete, find re-bar and connect copper by weld? Also what would I do about tie wires?

you do not have to weld the connection just use a proper compression fitting & seal the opening with concrete -- the UFER is a stand alone type electrode does not require any other & is usually connected before the footer pour not really a choice item-- the ground loop, ground rods & copper water piping would not have to be installed would not be required for a electrode system they can be optional -- though any of those that are installed by choice would have to be part of the electrode system.

 

[kwired]

The site is in Middle East and they seem to have an odd way of doing things. So if I have a ground loop around the building, grounds rods on the loop, ground the water pipes and ground the service entrance I'm actually ok? Of course lps will also connect to the loop.

I also read the standard as ufer must be connected too, so I'm still a little uneasy about it. If I insist to ground the re-bar how would they do it physically? Break concrete, find re-bar and connect copper by weld? Also what would I do about tie wires?

Does NEC apply? The answers you have gotton so far are based on NEC.

You might want to have a talk with the concrete contractor and/or the structural engineer before just breaking out concrete. I would hate to be responsible for weakening the foundation of a 14 floor building. If they were at fault for not allowing you to make a connection to the CEE, then make them make it accessible to you instead of making it accessible yourself.

 

[petersonra]

the difference to me is the electrode system is important part of the electrical system so using a couple of ground rods (worthless but compliant) compared to a UFER is a big difference.

"if there is no CEE or building structure that qualifies as a GE pound a couple of rods and be done with it." absolutely in fact most likely be required in those conditions though I never had seen a single (or double) ground rod meet the 25 ohm rule.

The 25 Ohm rule only applies to a single rod. It is irrelevant to any other type of GE.

In any case, what makes you think a Ufer will do anything for you that a pair of rods won't? It is not like it changes anything substantially. A Ufer might be lower impedance but does that really matter? The answer is to be found in the code.

(1) Electrical System Grounding. Electrical systems that
are grounded shall be connected to earth in a manner that
will limit the voltage imposed by lightning, line surges, or
unintentional contact with higher-voltage lines and that will
stabilize the voltage to earth during normal operation.

Suppose we have 2 rods that provide 100 Ohms impedance to earth versus a Ufer that provides 1 Ohm to earth. How will the lower impedance matter any to what we are trying to accomplish by earthing it in the first place?

 

[mwm1752]

The 25 Ohm rule only applies to a single rod. It is irrelevant to any other type of GE.

In any case, what makes you think a Ufer will do anything for you that a pair of rods won't? It is not like it changes anything substantially. A Ufer might be lower impedance but does that really matter? The answer is to be found in the code.



Suppose we have 2 rods that provide 100 Ohms impedance to earth versus a Ufer that provides 1 Ohm to earth. How will the lower impedance matter any to what we are trying to accomplish by earthing it in the first place?

a better path to earth should be the goal -- believe what you want -- or argue what ever lol

 

[kwired]

The 25 Ohm rule only applies to a single rod. It is irrelevant to any other type of GE.

In any case, what makes you think a Ufer will do anything for you that a pair of rods won't? It is not like it changes anything substantially. A Ufer might be lower impedance but does that really matter? The answer is to be found in the code.



Suppose we have 2 rods that provide 100 Ohms impedance to earth versus a Ufer that provides 1 Ohm to earth. How will the lower impedance matter any to what we are trying to accomplish by earthing it in the first place?

If you can only get 100 ohms with two rods chances are you aren't getting down to only one ohm with the CEE, unless it is a really large CEE. But I also agree that it really doesn't matter. Inspectors get fixed on the importance of a GES, when in reality unless you are not connected to a utility system with many grounding electrodes connected to it, one missing electrode at one service isn't as big of a deal as they want it to be.

Areas with a high level of lightning incidents maybe it becomes somewhat higher importance though.

 

[petersonra]

a better path to earth should be the goal -- believe what you want -- or argue what ever lol

Why? How does a better path to Earth serve any useful purpose?

 

[Ponchik]

I get your point -- it would not be considered an electrode ( as it is coated & cannot contact earth & not pertain to electrode codes.) We are going to see fiberglass type rebar being used if the future so that would not qualify also -- But how simple it is to get 20' of min 4# rebar or use CU for the most reliable electrode that exist especially in a large multi use building -- I'd bet there is some steel encasement somewhere with building steel. I would like to think the GC did his job properly & a fair explanation is out there

To me a CEE is much better than two ground rods and it is very simple to install two 10' rebars and make that your CEE. However, the code says "If available....." but at the time of the installation the rebar is not available, or they used coated rebar, or the rebar is fiberglass... (or whatever the case may be) you get my point.

At the time the rebar (CEE is not available) again, the installer could have gone to store and buy two 10' electrodes, but....

 

[kwired]

To me a CEE is much better than two ground rods and it is very simple to install two 10' rebars and make that your CEE. However, the code says "If available....." but at the time of the installation the rebar is not available, or they used coated rebar, or the rebar is fiberglass... (or whatever the case may be) you get my point.

At the time the rebar (CEE is not available) again, the installer could have gone to store and buy two 10' electrodes, but....

Been about 10 years now (pretty sure the change was 2008, maybe even 2005) but code used to say "if available" or something close to that. It now says "that are present" which means if it is there you must use it.

 

[Gilf]

Been about 10 years now (pretty sure the change was 2008, maybe even 2005) but code used to say "if available" or something close to that. It now says "that are present" which means if it is there you must use it.

I agree. Also the site has very high ground water level, so I think that without CEE the grounding would not be adequate. Does it count connected if I ground the building steel at the columns of 9th floor and take it down so I don't have to break the concrete of the foundation since the columns are connected to the foundation?

 

[dkidd]

I agree. Also the site has very high ground water level, so I think that without CEE the grounding would not be adequate. Does it count connected if I ground the building steel at the columns of 9th floor and take it down so I don't have to break the concrete of the foundation since the columns are connected to the foundation?

No.

"Metallic components shall be encased by at least 50 mm
(2 in.) of concrete and shall be located horizontally within that
portion of a concrete foundation or footing that is in direct
contact with the earth or within vertical foundations or structural
components or members that are in direct contact with
the earth. If multiple concrete-encased electrodes are present
at a building or structure, it shall be permissible to bond only
one into the grounding electrode system."

I have known of AHJs that make the contractor dig down and cut into the foundation to make the connection. Saying "I forgot" doesn't cut it.

 

[kwired]

No.

"Metallic components shall be encased by at least 50 mm
(2 in.) of concrete and shall be located horizontally within that
portion of a concrete foundation or footing that is in direct
contact with the earth or within vertical foundations or structural
components or members that are in direct contact with
the earth. If multiple concrete-encased electrodes are present
at a building or structure, it shall be permissible to bond only
one into the grounding electrode system."

I have known of AHJs that make the contractor dig down and cut into the foundation to make the connection. Saying "I forgot" doesn't cut it.

The CEE and the building steel could certainly be bonded together. One problem though is the EI did not see it before it was encased so he still doesn't know if they are bonded or not.