2 services 1 building GEC

[yired29]

Here is a debate I’ve had with a few people. Large building has one service owner decides to partition off a section and rent that part. Original service is 1200 amps with water main grounding electrode sized at 3/0, CEE #4 sole connection, building steel 3/0, 2 ground rods with # 6 sole connection all tied together at main service neutral bus. The new section of the building gets special approval for a second service 400 amps. Here is were the debate begins on the new service one argument is that service needs all electrodes described above and sized based on the new service conductor size and the other argument is it would only need to go to building steel based on the new service conductor size.

The two services are 400' apart and all the original electrodes are by the first service.

2005 NEC
I would like to hear your thoughts on this subject.
Code sections would be nice.
I know what side of the debate I’m on just would like some more opinions
Hope I've given enough info. Any question I'll try to answer

 

[mcclary's electrical]

Here is a debate I?ve had with a few people. Large building has one service owner decides to partition off a section and rent that part. Original service is 1200 amps with water main grounding electrode sized at 3/0, CEE #4 sole connection, building steel 3/0, 2 ground rods with # 6 sole connection all tied together at main service neutral bus. The new section of the building gets special approval for a second service 400 amps. Here is were the debate begins on the new service one argument is that service needs all electrodes described above and sized based on the new service conductor size and the other argument is it would only need to go to building steel based on the new service conductor size.

The two services are 400' apart and all the original electrodes are by the first service.

2005 NEC
I would like to hear your thoughts on this subject.
Code sections would be nice.
I know what side of the debate I?m on just would like some more opinions
Hope I've given enough info. Any question I'll try to answer

If you have a hand book, see exhibits 250.10, 250.11 250.12, 250.13, 250.14, 250.15

 

[augie47]

This may help:
250.24 Grounding Service-Supplied Alternating-Current Systems.
(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).

250.58 Common Grounding Electrode.
Where an ac system is connected to a grounding electrode in or at a building or structure, the same electrode shall be used to ground conductor enclosures and equipment in or on that building or structure. Where separate services, feeders, or branch circuits supply a building and are required to be connected to a grounding electrode(s), the same grounding electrode(s) shall be used.
Two or more grounding electrodes that are bonded together shall be considered as a single grounding electrode system in this sense.

 

[yired29]

If you have a hand book, see exhibits 250.10, 250.11 250.12, 250.13, 250.14, 250.15

I don't think those exibits apply.
250.10 is for a 4 wire service with only 3 wire loads no grounded conductor.
250.11 250.12 all service mains are located in the same assembly.
250.13-250.15 are for seperatly derived systems.

 

[yired29]

This may help:
250.24 Grounding Service-Supplied Alternating-Current Systems.
(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).

250.58 Common Grounding Electrode.
Where an ac system is connected to a grounding electrode in or at a building or structure, the same electrode shall be used to ground conductor enclosures and equipment in or on that building or structure. Where separate services, feeders, or branch circuits supply a building and are required to be connected to a grounding electrode(s), the same grounding electrode(s) shall be used.
Two or more grounding electrodes that are bonded together shall be considered as a single grounding electrode system in this sense.

This is where I'm looking but what is your stance.

Just go to building steel at second service

Or

Grounding electorde conductor needs to go to original service electrode location.

 

[augie47]

Since the original install has separate GEC back to the service, the new service can't depend on "hitting" just one electrode.
The premises is the GEC system must be intact for either service if the other one is removed.
The new service can go to each electrode present or it can go to one and then that one be directly connected to others.
The "route" can not depend on the common connection in the 1st service.

 

[yired29]

Since the original install has separate GEC back to the service, the new service can't depend on "hitting" just one electrode.
The premises is the GEC system must be intact for either service if the other one is removed.
The new service can go to each electrode present or it can go to one and then that one be directly connected to others.
The "route" can not depend on the common connection in the 1st service.

So if we just brought all electrode conductors to the water and only 1 to the first service then the second service would only need to go to building steel 400' away? Of course from water to steel at the first service would have to be sized for the largest service conductors.

 

[augie47]

Correct. If they had originally connected from one electrode to the other, then you could also just hit the one (assuming all interconnections are properly sized). Had thy gone from water to steel, to UFER, etc. you could use their loop.
Since they ran independent GEC, you will need to do also, or make your own loop.

 

[yired29]

Correct. If they had originally connected from one electrode to the other, then you could also just hit the one (assuming all interconnections are properly sized). Had thy gone from water to steel, to UFER, etc. you could use their loop.
Since they ran independent GEC, you will need to do also, or make your own loop.

The argument to this is you are using building steel as a conductor to connect to the other electrodes. As it has been presented to me.

 

[RooKie12]

I take it since your saying it's a new service it has it's own service lateral and meter supplying it? Or it is a 400A panel feed off the 1200A service

 

[yired29]

The argument to this is you are using building steel as a conductor to connect to the other electrodes. As it has been presented to me.

It has been my position that if a properly sized GEC went from the water electrode or concrete encased electrode to building steel 250.52 (A) 2 (2) that would create a common grounding electrode system (250.58).

With that said we would be able to use building steel at any point in the building as the grounding electrode for any number of services any distance from the other electrodes and comply with (250.50).

I understand the AHJ has the final word and would need his approval but I feel this is a code compliant install.

 

[yired29]

I take it since your saying it's a new service it has it's own service lateral and meter supplying it? Or it is a 400A panel feed off the 1200A service

Yes it is a new service with its own meter and another service lateral to the same serving utlity transformer.

 

[augie47]

The argument to this is you are using building steel as a conductor to connect to the other electrodes. As it has been presented to me.

I think at one time that was the view. In recent Codes, if the steel is effectively grounded per 250.52(A)(2) or bonded to one of the electrodes in250.52(A)(5 )or (A)(7) or (A)(3) apparently makes the steel an electode and you can connect to it

It has been my position that if a properly sized GEC went from the water electrode or concrete encased electrode to building steel 250.52 (A) 2 (2) that would create a common grounding electrode system (250.58).

With that said we would be able to use building steel at any point in the building as the grounding electrode for any number of services any distance from the other electrodes and comply with (250.50).

I understand the AHJ has the final word and would need his approval but I feel this is a code compliant install.

I agree

 

[yired29]

I think at one time that was the view. In recent Codes, if the steel is effectively grounded per 250.52(A)(2) or bonded to one of the electrodes in250.52(A)(5 )or (A)(7) or (A)(3) apparently makes the steel an electode and you can connect to it

I agree

Where does everybody else stand on this situation?

 

[Jim W in Tampa]

Cant say i like it but assuming we are talking major steel as a metal building and roof i think we are safe. Is there any chance first part of building might get demo ? Rare but does happen. If being called seperate building then i think it should meet ALL requirements alone. Don't know if if we can use another building as part of service. I say leave it up to ahj as only he can see total picture. Is there any reason not to make it stand as a seperate building ?

 

[yired29]

Cant say i like it but assuming we are talking major steel as a metal building and roof i think we are safe. Is there any chance first part of building might get demo ? Rare but does happen. If being called seperate building then i think it should meet ALL requirements alone. Don't know if if we can use another building as part of service. I say leave it up to ahj as only he can see total picture. Is there any reason not to make it stand as a seperate building ?

To make it stand as seperate building it would need a fire wall.

NEC 2005 Article 100

(Building) A structure that stands alone or is cut off from adjoining structures by fire walls with all openings therin protected by approved fire doors.

2006 IBC Chapter 7 Section 702 Definitions.

(Fire Wall) A fire-resistance-rated wall having protected openings, which restricts the spread of fire and extends continuously from the foundation to or through the roof, with sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall.

This would be very costly.

 

[Jim W in Tampa]

To make it stand as seperate building it would need a fire wall.

NEC 2005 Article 100

(Building) A structure that stands alone or is cut off from adjoining structures by fire walls with all openings therin protected by approved fire doors.

2006 IBC Chapter 7 Section 702 Definitions.

(Fire Wall) A fire-resistance-rated wall having protected openings, which restricts the spread of fire and extends continuously from the foundation to or through the roof, with sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall.

This would be very costly.

True but to get 2 services takes someting too and its more than just 2 tenants

 

[yired29]

True but to get 2 services takes someting too and its more than just 2 tenants

In the OP I believe i stated there is special permission. 230.2 (B)

 

[Jim W in Tampa]

In the OP I believe i stated there is special permission. 230.2 (B)

Then special rules apply too.

 

[yired29]

Then special rules apply too.

care to elaborate