Ground Ring requirement for electrical room espansion

[Smart $]

Why would it ever be "illegal" to remove a GE as long as the resulting installation still met code? ...

Let's say the original installation was made under EE sealed and AHJ approved for construction plans. The GES was designed better than CODE minimum for undisclosed reasons.

You come in years later to make a semi-major building improvement. You were not part of the original construction and have no idea why the GES is as it is. You "break" an existing GES and do not repair because you know the GES that remains intact meets Code minimum. Did you break the law or not?

 

[topgone]

Let's say the original installation was made under EE sealed and AHJ approved for construction plans. The GES was designed better than CODE minimum for undisclosed reasons.

You come in years later to make a semi-major building improvement. You were not part of the original construction and have no idea why the GES is as it is. You "break" an existing GES and do not repair because you know the GES that remains intact meets Code minimum. Did you break the law or not?

If I may chime in, I don't think it would be correct to say that the new engineer "came in years later to make a semi-major building improvement" will not exert efforts to know where, why, how, etc the GES of the old building was. It may not be true with other building owners but it is customary to demand "As-built" plans from the original contractor. That said, information can be gleaned from the blue/white prints and there wil be less problems. Solved!

 

[petersonra]

Let's say the original installation was made under EE sealed and AHJ approved for construction plans. The GES was designed better than CODE minimum for undisclosed reasons.

You come in years later to make a semi-major building improvement. You were not part of the original construction and have no idea why the GES is as it is. You "break" an existing GES and do not repair because you know the GES that remains intact meets Code minimum. Did you break the law or not?

there is no requirement to be found in the code prohibiting such a thing. what would make such an action "illegal"? unless there is some special local requirements around such things (and if they exist they are pretty rare), there is nothing "illegal".

that would be akin to saying you could not repaint a room because the architects sealed plans said it should be a specific color and you wanted it to be a different color down the road.

 

[Smart $]

there is no requirement to be found in the code prohibiting such a thing. what would make such an action "illegal"? unless there is some special local requirements around such things (and if they exist they are pretty rare), there is nothing "illegal".

that would be akin to saying you could not repaint a room because the architects sealed plans said it should be a specific color and you wanted it to be a different color down the road.

Well it appears we will remain forever on different sides of this issue...

 

[kwired]

Let's say the original installation was made under EE sealed and AHJ approved for construction plans. The GES was designed better than CODE minimum for undisclosed reasons.

You come in years later to make a semi-major building improvement. You were not part of the original construction and have no idea why the GES is as it is. You "break" an existing GES and do not repair because you know the GES that remains intact meets Code minimum. Did you break the law or not?

As I see it you changed what was part of original design specs. But in the OP's case we are partially demolishing and redesigning something existing as well. NEC requirements are still met, maybe the "law" is more then NEC requirements in some places but not everyplace. I have never worked on a project where the inspector made certain my installation was to the plans, all they have ever looked for is NEC compliance, design beyond NEC has always been between installers and designers around here.

What if you came in later and replaced a designer specified specification grade device with a non specification grade device or replaced a stainless wall plate with a plastic wall plate?

 

[Smart $]

...

What if you came in later and replaced a designer specified specification grade device with a non specification grade device or replaced a stainless wall plate with a plastic wall plate?

Hinges on whether it is done with or without approval of appropriate parties.

 

[kwired]

Hinges on whether it is done with or without approval of appropriate parties.

I see it as no different then buying a new car, new appliance, or other similar equipment. Designer has made a design and the contractor builds it to that design spec. It is only "new" the day the owner take occupancy and starts deteriorating immediately (may not be at a very fast pace but is definitely not improving). What owner does with it afterwards is totally up to the owner. Now the designer/installer can provide a warranty, but can also decline to warranty something that has not been maintained to original specification or was authorized by designer to change the specification.

 

[kingpb]

Obviously there is a difference of opinion. I say opinion because those arguing about the nuances of this post don't have a horse in the race and thus are most likely not akin to all the details even present; design or political.

In all the back and forth I haven't seen where anyone has expressed what the intent/use of this ground ring is for. Also, a prophetic reminder, that the "CODE" (all caps because it is obviously on the same level as GOD) is minimum safety requirements, not a design guide.

So, what is the ring being used for? Would like to hear from the OP.

 

[philly]

I apologize for chiming back in late on this but the past few weeks have been hectic.

I was actually able to make it out to the site to inspect the existing building that is being expanded only to find that there does not appear to be an existing ground ring or really any grounding electrode for that matter. We were told there was an existing ground ring but when contractor started excavating around building there was no ground ring to be found, so I apologize for stating that assumption.

Here is what I did find:

As I mentioned earlier this building houses two 480V MCC's which are fed from as double ended substation in a building about 100ft or so away. I found that the ductbanks that feed these MCC's have a 4/0 ground wire run in the ductbank that come up through the concrete slab and attached to the ground bus in the MCC. The 4/0 ground wire in ductbank runs back to the substation building where I know for a fact there is an extensive grounding system with multiple ground rods, rings, etc... The only issue however is that this ductbank goes through manholes so I'm not sure that that this ground wire is continuous all the way back through the manholes (under investigation). So it appears that the only grounding this room has is the ground wire coming through the existing ductbanks that connect to the MCC ground buses. These ductbanks are being replaced, but the ground wire will also be replaced and re-run as well.

Inside the room there are 3 panels and a dry type that are all connected to a ground bar mounted on the wall. the ground bar from what I could tell was not connected to the physical ground at any point but rather had a ground wire run in a conduit that went back and connected to the ground bus in one of the MCC's.

So I guess in seeing this my other question becomes weather or not the existing grounding electrodes at the adjacent substation building (100ft) away can be utilized as the grounding electrodes for the building where the MCC's are via the grounds in the ductbanks? Is there a limit on how far away the grounding electrodes can be.

With all that said we are still going to expand the existing buildings that the MCC's are in and need to specify grounding for the expansion. Obviously as others have mentioned, the easiest thing to do is to utilize a CEE in the new foundation. However given this new information on the existing buildings grounding is there a need or requirement to tie the expansion buildings ground into the exiting buildings ground via the MCC ground bus?

This thread has been helpful and the one thing I did learn was the requirement in 250.50 to use all available grounding electrodes weather they be CEE's, building steel, water pipes, etc... To what distance does this requirement apply? For instance if there are water pipes running in the vicinity of the building are they required to be utilized. Say the pipe are 50ft or even 75ft away, are they required to be used? Is there a distance/depth requirement for having to use a water pipe if it is present?

Lastly assuming that I only need to use a CEE to meet the minimum requirement, is it a good idea to install additional grounding electrodes or rings around the expansion? I know the NEC dictates the minimum and is not a design guide, but most industrial designs I see seem to utilize a ground ring which is tied into the rebar in the foundation. Do you think it would be wise to try to somehow tie into the exiting buildings foundation rebar once the wall is removed an there is possible rebar that is exposed or can be made exposed for connection?

 

[kingpb]

My 2 cents says you should make the "new" building or expansion, ground stand on its own, and tie into the existing in two places.

 

[philly]

My 2 cents says you should make the "new" building or expansion, ground stand on its own, and tie into the existing in two places.

That was the original plan however based on what I found above I am wondering if the grounding in the existing building is adequate and weather or not it should be enhanced as part of the building expansion.

 

[Smart $]

That was the original plan however based on what I found above I am wondering if the grounding in the existing building is adequate and weather or not it should be enhanced as part of the building expansion.

If there is no grounding electrode system (GES) in the building being expanded, then it is definitely not adequate under the NEC. I recommend that at the very least you create a CEE with the expansion. If demo gets into the existing foundation, by all means tie new into existing rebar if available, or run a separate GEC if need be.

You cannot use distant electrodes or grounding systems. Code requires the GES at each building or structure. Many of the electrodes required/permitted are external to a building or structure footprint. There is no specified distance, but I'll say over 10' beyond the footprint would be stretching it.

Also a grounding bar around the room is somewhat commonplace for industrial installations. I don't know where it stems from, but under the NEC, it can be used for bonding (required or redundant), but it cannot be used as a substitute for running an EGC.

 

[philly]

If there is no grounding electrode system (GES) in the building being expanded, then it is definitely not adequate under the NEC. I recommend that at the very least you create a CEE with the expansion. If demo gets into the existing foundation, by all means tie new into existing rebar if available, or run a separate GEC if need be.

I guess this leads to another question of mine which is weather or not this room containing MCC's required as GES? Do all buildings require GES's or only where there is service equipment or separately derived sysems? So for instance if it was just MCC's in this buildings would it require a GES? No If I have the panelbaords and transformer in this room along with the MCC's does it now require a GES? Any specific code references that dictate this?

So it sounds like you are saying the remote GES the building 100ft away cannot be used as the GES for the building in question via the ground in the ductbank. I guess then this ground in the ductbank connected back to the other buildings GES is above and beyond the requirement of the NEC and is just a standard practice?

 

[GoldDigger]

I guess this leads to another question of mine which is weather or not this room containing MCC's required as GES? Do all buildings require GES's or only where there is service equipment or separately derived sysems? So for instance if it was just MCC's in this buildings would it require a GES? No If I have the panelbaords and transformer in this room along with the MCC's does it now require a GES? Any specific code references that dictate this?

So it sounds like you are saying the remote GES the building 100ft away cannot be used as the GES for the building in question via the ground in the ductbank. I guess then this ground in the ductbank connected back to the other buildings GES is above and beyond the requirement of the NEC and is just a standard practice?

It depends on what the "ground" conductor in the freeder actually is.
You need to have an EGC, which is not part of either building's GES and is sized by the rules for EGCs and thosevfor GECs or bonding jumpers.
The NEC only requires that all electrodes for one building be bonded together to make a GES for that building.

 

[Smart $]

I guess this leads to another question of mine which is weather or not this room containing MCC's required as GES? Do all buildings require GES's or only where there is service equipment or separately derived sysems? So for instance if it was just MCC's in this buildings would it require a GES? No If I have the panelbaords and transformer in this room along with the MCC's does it now require a GES? Any specific code references that dictate this?

So it sounds like you are saying the remote GES the building 100ft away cannot be used as the GES for the building in question via the ground in the ductbank. I guess then this ground in the ductbank connected back to the other buildings GES is above and beyond the requirement of the NEC and is just a standard practice?

Every building requires its own GES if it has any electrical equipment. The only exception is a residential outbuilding served by a single branch circuit. The NEC does not prohibit tying multiple building GES's together, but this in no way alleviates the GES required for any single building or structure. The GES at the building 100ft away cannot be used for the building being discussed.

However, the ground wire run with the duct bank may actually qualify as a CEE, subject to AHJ interpretation. In most cases the ground conductor(s) are encased in the concrete, not run in the duct... and in no way do these alleviate the requirement for an EGC run with circuit conductors.

 

[kwired]

I guess this leads to another question of mine which is weather or not this room containing MCC's required as GES? Do all buildings require GES's or only where there is service equipment or separately derived sysems? So for instance if it was just MCC's in this buildings would it require a GES? No If I have the panelbaords and transformer in this room along with the MCC's does it now require a GES? Any specific code references that dictate this?

So it sounds like you are saying the remote GES the building 100ft away cannot be used as the GES for the building in question via the ground in the ductbank. I guess then this ground in the ductbank connected back to the other buildings GES is above and beyond the requirement of the NEC and is just a standard practice?

250.32 Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s).


(A) Grounding Electrode.
Building(s) or structure(s) supplied by feeder(s) or branch circuit(s) shall have a grounding electrode or grounding electrode system installed in accordance with Part III of Article 250.....

As mentioned there is an exception for a building or structure supplied by only a single branch circuit.

 

[philly]

Every building requires its own GES if it has any electrical equipment.

Ok so even if the building only has one panel it still is required to have a GES. I assume this would apply any sort of structure as well such as a metal structure you may find on an industrial site?

The NEC does not prohibit tying multiple building GES's together, but this in no way alleviates the GES required for any single building or structure. The GES at the building 100ft away cannot be used for the building being discussed.

So every building or structure must have its own GES located at that building or structure within reasonable distance (say 10ft or so) and connect back to a remote GES located elsewhere to meet the requirements of a local GES?

You need to have an EGC, which is not part of either building's GES and is sized by the rules for EGCs and thosevfor GECs or bonding jumpers.

Yes there will be EGC's run with the MCC feeder and size accordingly per 250.122. It looks like from reading 250.32 these EGC's will tie into the MCC ground bus and the ground bus must in turn connect to the GES in the building. Is this correct?

 

[philly]

So based on the NEC and others responses it would appear that this building does not have a GES. It appears that the MCC feeders have an EGC and there is a ground wire run in the MCC feeder ductbank connecting the MCC ground bus to a GES system at another building, however none of this constitutes as a GEC per 250.32 and 250.50. (Except possibly the ground wire in the duct bank being interpreted as a CEE as was mentioned above.)

So it sounds like there are a couple of options here to make this building have a GES which meets NEC requirements.

1) Simply drive a ground rod per 250.52(A)(5) outside of the existing building and connect the ground rod to the ground bus in both the MCC's with a GEC. Can you connect a GEC to one MCC and then connect over to the other MCC or does the GEC need to be run to a common point before the MCC's?

2) Somehow tap into the existing slab and use the existing rebar as a CEE. After connecting to the rebar we would run a GEC that would need to connect to the MCC ground bus. Again does this need to go to a common point first? Is there any easy way to connect to existing rebar by simply chipping away at the slab?

3) Possibly utilize the ground wire run in the ductbank as a CEE (open to interpretation) The issue I see however is that the ground wire run in the ductbank has insulation and 250.52(A)(3)(2) requires a bare conductor to be used as part of the CEE. So from what I can tell this insulated ground in the ductbank would not count as a CEE. Another option we would have is so make a new CEE by running 4AWG bare copper outside of the building and making a new CEE. Is making a new CEE a better option than simply installing a ground rod in option #1?

These appear to be the options to satisfy the GES requirements for the existing building. No matter what option is chosen the GES will have to connect to the equipment grounds in the MCC's correct? Is one option better than another?

Now in terms of the building expansion we will have the luxary of installing a new GES. With this new GES we can then try to tie it back into the existing building. I suppose we could tie the new expansion GEC to a common ground bus on the wall and then connect this ground bus to the MCC grounds in the MCC's? Or does the GEC need to go right from the GES to the MCC (I'm a bit confused on the order of things)

Can a GEC be run inside of RMC conduit? For instance lets say we install a ground rod outside the exiting building. When the GEC enters to room can it be run in RMC to the MCC's to connect to the ground bus?

 

[philly]

On other thought that comes to mind with the expansion of the building. It has been mentioned to tie the new expansion GEC into the existing buildings slab if possible. I'm not sure how easy it is to simply tie into an existing slab? Do you think it is worth the trouble to try to tie into the existing slab, or simply just connect to a ground bus or other common location in the room?

Even if we tied into the existing slab we would still need to connect the MCC ground bus over to the GES of the new expansion correct (since the MCC ground bus does not have a GEC to the existing slab)

 

[kwired]

So based on the NEC and others responses it would appear that this building does not have a GES. It appears that the MCC feeders have an EGC and there is a ground wire run in the MCC feeder ductbank connecting the MCC ground bus to a GES system at another building, however none of this constitutes as a GEC per 250.32 and 250.50. (Except possibly the ground wire in the duct bank being interpreted as a CEE as was mentioned above.)

So it sounds like there are a couple of options here to make this building have a GES which meets NEC requirements.

1) Simply drive a ground rod per 250.52(A)(5) outside of the existing building and connect the ground rod to the ground bus in both the MCC's with a GEC. Can you connect a GEC to one MCC and then connect over to the other MCC or does the GEC need to be run to a common point before the MCC's?

2) Somehow tap into the existing slab and use the existing rebar as a CEE. After connecting to the rebar we would run a GEC that would need to connect to the MCC ground bus. Again does this need to go to a common point first? Is there any easy way to connect to existing rebar by simply chipping away at the slab?

3) Possibly utilize the ground wire run in the ductbank as a CEE (open to interpretation) The issue I see however is that the ground wire run in the ductbank has insulation and 250.52(A)(3)(2) requires a bare conductor to be used as part of the CEE. So from what I can tell this insulated ground in the ductbank would not count as a CEE. Another option we would have is so make a new CEE by running 4AWG bare copper outside of the building and making a new CEE. Is making a new CEE a better option than simply installing a ground rod in option #1?

These appear to be the options to satisfy the GES requirements for the existing building. No matter what option is chosen the GES will have to connect to the equipment grounds in the MCC's correct? Is one option better than another?

Now in terms of the building expansion we will have the luxary of installing a new GES. With this new GES we can then try to tie it back into the existing building. I suppose we could tie the new expansion GEC to a common ground bus on the wall and then connect this ground bus to the MCC grounds in the MCC's? Or does the GEC need to go right from the GES to the MCC (I'm a bit confused on the order of things)

Can a GEC be run inside of RMC conduit? For instance lets say we install a ground rod outside the exiting building. When the GEC enters to room can it be run in RMC to the MCC's to connect to the ground bus?

Maybe I am reading it wrong but you can not supply a building with two feeders per 225.30 other then special conditions mentioned in 225.30(A) which mentions:Fire pumps
Emergency systems
Legally required standby systems
Optional standby systems
Parallel power production systems
Systems designed for connection to multiple sources of supply for the purpose of enhanced reliability

You can supply a building with up to six service disconnecting means and they can be supplied by conductors connected together at the source end but land in six different disconnecting means at the building served, but you can only run a single feeder when supplying a building with a feeder so if you are in compliance with that - there is no second place to have to worry about where to tie a GEC to. You could have one feeder to the building though with up to six disconnecting means at the building, in that case the GEC would need to connect to some "common" point in the supply, like wherever the feeder branches into the multiple disconnecting means.