250.30(a)(4)

[Smart $]

This is the part you keep sighting that is not allowed (in red)

...

Ditto. . .

As I said, the metal building frame is a grounding electrode (provided it meets the requirements). Only under special circumstance is it permitted to run an EGC to an electrode, or a grounding electrode conductor, and the topic of discussion does not qualify as such.

We can, however, utilize the metal building frame [again, provided it meets the requirements of 250.52(A)(2)] as an electrode for SDS/MSDS's, and the GEC must meet the requirements of 250.30(A)(4).

 

[Smart $]

1910.5(c)
1910.5(c)(1)
If a particular standard is specifically applicable to a condition, practice, means, method, operation, or process, it shall prevail over any different general standard which might otherwise be applicable to the same condition, practice, means, method, operation, or process. For example, 1915.23(c)(3) of this title prescribes personal protective equipment for certain ship repairmen working in specified areas. Such a standard shall apply, and shall not be deemed modified nor superseded by any different general standard whose provisions might otherwise be applicable, to the ship repairmen working in the areas specified in 1915.23(c)(3).

OSHA should be a good reference.

Yes, it is...



...for OSHA standards.


Now show us something similar, AND authoritative, for NFPA Standards...

 

[Smart $]

NFPA70:2008:100 Premises Wiring (Systems).
...
Such wiring does not include wiring internal to ... similar equipment.

NPFA79:2007:100 3.3.56 Industrial Machinery (Machine).
...
The associated electrical equipment, including the logic controller(s) and associated software or logic together with the machine actualors and sensors, are consideredc as part of the industrial machine. See also NFPA70:2008:670.2

Yes I realize this requires some interpretation. However NEC 670.2 and NFPA79 say that the wiring is internal to the machine. NEC 100 says internal wiring is not premises wiring and SDS requires premises wiring. By this train IMO therefore there is no SDS.

Even though there is no SDS, again IMO, the NFPA79 requires an EGC but not 3/0.

Well, what you quoted from 79 does not say what you think it does. It says "associated electrical equipment". It does not say interconnecting wiring. For example, I have a furnace which the thermostat can be considered part of the "machine"; for without it, the furnace would not operate as intended. However, the wiring between the furnace and [remote-mounted] thermostat is not part of the "machine"; rather it is premises wiring and falls under the NEC, not NFPA79.

In an industrial environment, I would consider wiring confined to a "skid" machine as falling entirely under NFPA79. That is, the wiring both begins and ends on the skid. Any other wiring connected to that skid qualifies as premises wiring.

 

[don_resqcapt19]

The building steel is the "Grounding Electrode System". It replaces grounding electrodes since you can't punch through concrete and expect to find water within 50ft of depth. It follows NFPA70:2008:250.52(A)(2) requirements. The EGC is brought from the building steel.

It is never permitted to bring the EGC for a circuit from the building steel. The EGC must originate at the system or main bonding jumper for a grounded system.

 

[pfalcon]

Yes, it is...
...for OSHA standards.
Now show us something similar, AND authoritative, for NFPA Standards...

You are asking for snipes. NFPA has no legal authority of its own. It has authority because OSHA grants that authority. OSHA also takes the NEC authority away under conditions listed in 1910.5(c)(1)

The other source of authority is state law. I haven't bothered looking for that since OSHA applies across all the states.

 

[pfalcon]

It is never permitted to bring the EGC for a circuit from the building steel. The EGC must originate at the system or main bonding jumper for a grounded system.

There is no grounded system. The industrial power is 480VAC ungrounded Delta (Old Style)or 480VAC high-resistance Wye (Modern Style). Both are 3-wire through the buss. The buss raceway is exothermically welded to building steel.

 

[pfalcon]

Well, what you quoted from 79 does not say what you think it does. It says "associated electrical equipment". It does not say interconnecting wiring. For example, I have a furnace which the thermostat can be considered part of the "machine"; for without it, the furnace would not operate as intended. However, the wiring between the furnace and [remote-mounted] thermostat is not part of the "machine"; rather it is premises wiring and falls under the NEC, not NFPA79.

In an industrial environment, I would consider wiring confined to a "skid" machine as falling entirely under NFPA79. That is, the wiring both begins and ends on the skid. Any other wiring connected to that skid qualifies as premises wiring.

Your example is poor for a specific set of reasons. The furnace you describe is a facility furnace not an industrial furnace. The facility furnace does have remote-mounted thermostats. The industrial furnaces do not. The facility furnace does fall under the NEC but we were not discussing that type. The industrial furnace falls under the NFPA79. And yes, the industrial furnace can be "skid" mounted. Our skid is typically a specially poured floor of concrete rather than metal. But we could cut the service to the machine, unanchor the concrete, and tote the thing away without disturbing the surrounding equipment.

 

[Smart $]

You are asking for snipes. NFPA has no legal authority of its own. It has authority because OSHA grants that authority. OSHA also takes the NEC authority away under conditions listed in 1910.5(c)(1)

I am not disputing authority granted through OSHA. I am contesting your assertion that the NEC is the general standard and NFPA79 is the specific standard.

Read on...

Your example is poor for a specific set of reasons. The furnace you describe is a facility furnace not an industrial furnace. The facility furnace does have remote-mounted thermostats. The industrial furnaces do not. The facility furnace does fall under the NEC but we were not discussing that type. The industrial furnace falls under the NFPA79. And yes, the industrial furnace can be "skid" mounted. Our skid is typically a specially poured floor of concrete rather than metal. But we could cut the service to the machine, unanchor the concrete, and tote the thing away without disturbing the surrounding equipment.

You assume too much

Debate this...

NFPA 79, 2007 Edition

1.4 Specific Provisions Other Than NFPA 79. The size and overcurrent protection of the supply conductors to a machine shall be covered by NFPA 70, National Electrical Code? (NEC? ), Article 670. The wiring between component machines of an industrial manufacturing system shall be covered by NFPA 70, National Electrical Code.

Exception: Wiring of component machines of an industrial manufacturing system that is supplied by the manufacturer and an integral part of the system, is adequately protected and supported, and meets the requirement of this standard.

1.5* Specific Provisions Not Made in Relation to NFPA 70. On any point for which specific provisions are not made in this standard, the provisions of NFPA 70, National Electrical Code, shall be observed.

With all that said, there is not enough information provided by the OP'er to conclude which standard should be used in this situtation. However, the fact he said "they" require installation of the 3/0 leads me to believe someone knows for certain the NEC is the appropriate standard.

 

[don_resqcapt19]

There is no grounded system. The industrial power is 480VAC ungrounded Delta (Old Style)or 480VAC high-resistance Wye (Modern Style). Both are 3-wire through the buss. The buss raceway is exothermically welded to building steel.

The equipment grounding conductor still has to originate at the source of supply for the circuit and be run with the circuit conductors even for an ungrounded system. There is no code compliant way to run it to the building steel or used the building steel as the EGC.
PS: maybe your industrial power is ungrounded or resistance grounded, but a lot of it around here is 480Y/277.

 

[pfalcon]

I am not disputing authority granted through OSHA. I am contesting your assertion that the NEC is the general standard and NFPA79 is the specific standard.

Read on...
... <cut furnace issue. I think it's distracting from the main issue> ...
Debate this...

Quote:
NFPA 79, 2007 Edition

1.4 Specific Provisions Other Than NFPA 79. The size and overcurrent protection of the supply conductors to a machine shall be covered by NFPA 70, National Electrical Code? (NEC? ), Article 670. The wiring between component machines of an industrial manufacturing system shall be covered by NFPA 70, National Electrical Code.

Exception: Wiring of component machines of an industrial manufacturing system that is supplied by the manufacturer and an integral part of the system, is adequately protected and supported, and meets the requirement of this standard.

1.5* Specific Provisions Not Made in Relation to NFPA 70. On any point for which specific provisions are not made in this standard, the provisions of NFPA 70, National Electrical Code, shall be observed.

With all that said, there is not enough information provided by the OP'er to conclude which standard should be used in this situtation. However, the fact he said "they" require installation of the 3/0 leads me to believe someone knows for certain the NEC is the appropriate standard.

Aw, the debate part is easy. The wiring between my grinder and hob is NFPA70. The wiring in my grinder or hob is NFPA79. The wiring for my "flexible machine system (FMS)" of ten machines qualifies for the exception and stays NFPA79 except where NFPA79 is silent then it reverts back to NFPA70.

With all that said, the lack of information is why I asked for confirmation of additional information in post #16. Without that additional information the OP cannot be answered. As to someone using 3/0 confirming that someone knows something for certain, I suggest you spend more time looking at the daily picture submission. :grin: Do those DIY jobs demonstrate that someone knows for certain that something is acceptable?

 

[pfalcon]

The equipment grounding conductor still has to originate at the source of supply for the circuit and be run with the circuit conductors even for an ungrounded system. There is no code compliant way to run it to the building steel or used the building steel as the EGC.
PS: maybe your industrial power is ungrounded or resistance grounded, but a lot of it around here is 480Y/277.

Maybe you can give me a reference to running the EGC from the facility source considering the numerous industrial sites I've been to where the wire you request simply doesn't exist in any shape or form. The EGC originates at the installed buss head that clamps to each of three buss bars and once to the building steel grounding grid in place of a local grounding electrode.

Three buss bars and a buss frame are all there is to attach. It took a lot of research but to my best estimates the plant grounding system is an IT system while the machine tools are a TN-S system.

The progression at my site was
1) Ungrounded Delta (IT) 3-bar
2) Solidly Grounded Wye (TT) 4-bar
3) High-Resistance Wye (IT) 3-bar

Machine tools are all TN-S with the 2nd generation areas using the 4th bar EGC. 1st and 3rd generation use the buss frame exothermically welded to the building steel.

 

[pfalcon]

And I'm still having a struggle with your interpretation of:

250.52(A)(2) defines my building steel as a "Grounding Electrode".

Article 100 defines the EGC, the GEC, and the Grounding Conductor as the connections from my machine to the "Grounding Electrode" which 250.52(A)(2) says is my building steel.

And yet you say I can't get my EGC from the building steel. Which is to say I can't run my EGC to the Grounding Electrode. Exactly what am I missing?

 

[Smart $]

Aw, the debate part is easy. The wiring between my grinder and hob is NFPA70. The wiring in my grinder or hob is NFPA79. The wiring for my "flexible machine system (FMS)" of ten machines qualifies for the exception and stays NFPA79 except where NFPA79 is silent then it reverts back to NFPA70.

Your FMS under the 79's exception is perfectly fine... provided "The wiring between component machines" is "supplied by the manufacturer" at a minimum. In most the industrial environments I have been associated with in one way or another, this would be a rare case

... As to someone using 3/0 confirming that someone knows something for certain, I suggest you spend more time looking at the daily picture submission. :grin: Do those DIY jobs demonstrate that someone knows for certain that something is acceptable?

I didn't say anything was confirmed for certain... so don't be making it sound as though I did.

I'm also of the impression this is not a DIY job, too

If you want to dabate issues based on extreme speculation, it won't be with me

 

[Smart $]

... Exactly what am I missing?

The other parts of the NEC that say you can't bypass the point of the MBJ/SBJ to make a grounding connection at the load end of equipment supply conductors.

Sure, when it is all said and done, you technically have a grounding network. But if the prescribed connection of the network is A-B-C-D, it doesn't mean you get to make it A-D simply because it is electrically equivalent from one perspective.

 

[pfalcon]

Your FMS under the 79's exception is perfectly fine... provided "The wiring between component machines" is "supplied by the manufacturer" at a minimum. In most the industrial environments I have been associated with in one way or another, this would be a rare case


I didn't say anything was confirmed for certain... so don't be making it sound as though I did.

I'm also of the impression this is not a DIY job, too

If you want to dabate issues based on extreme speculation, it won't be with me

Yes, rare. The old FMS and a furnace area are the only systems I know of at our site. They were supplied by the manufacturer with transfer cars et al.

The other parts of the NEC that say you can't bypass the point of the MBJ/SBJ to make a grounding connection at the load end of equipment supply conductors.

Sure, when it is all said and done, you technically have a grounding network. But if the prescribed connection of the network is A-B-C-D, it doesn't mean you get to make it A-D simply because it is electrically equivalent from one perspective.

Eureka. Gotta love grounding/bonding terminology. Lots of confusion.

250.52(A)(2): The building steel conforms and is therefore the Grounding Electrode for the site.

The "Grounding Electrode Conductor" is the line from the building steel that accompanies the service conductors. The line is not the EGC.

The "Bonding Jumper" is located in the control panel. Facility side it is connected to the GEC; Machine side it is connected to the EGC and grounded conductor.

The mistake here is presuming that the service drop is to the facility. The actual service drop is to the machine tool. The machine tool is like a freaky house. The buss system is the POLCO.

 

[Smart $]

Eureka. Gotta love grounding/bonding terminology. Lots of confusion.

Confusion abounds, and will continue...

250.52(A)(2): The building steel conforms and is therefore the Grounding Electrode for the site.

It is but ONE grounding electrode for the site. To be compliant with current code, there has to be at least one other.

The "Grounding Electrode Conductor" is the line from the building steel that accompanies the service conductors. The line is not the EGC.

This is seldom true. Typically, if there is a grounding conductor which accompanies the service conductors, it is an Equipment Bonding Jumper (EBJ).

The "Bonding Jumper" is located in the control panel. Facility side it is connected to the GEC; Machine side it is connected to the EGC and grounded conductor.

You are mixing terminologies. The NEC does not recognize facility-side and machine-side terminology. Bonding Jumper is a vague terminology at best without a modifier. There are at least four types of bonding jumpers used in NEC grounding that I'm aware of:

1. Main Bonding Jumper (MBJ)—the interconnection of earth grounding conductors (GEC's and eBJ's*) to fault grounding conductors (EBJ's and EGC's) and the service grounded conductor if present,
2. System Bonding Jumper (SBJ)—quite similar to MBJ except for alternate energy sources not directly connected to a service,
3. Equipment Bonding Jumper (EBJ)—grounding conductors run with supply conductors on the line side of MBJ/SBJ, and
4. Electrode Bonding Jumpers (eBJ)—conductors connecting one electrode to another or the GEC, or bonding of GEC enclosures, protective raceways, etc.

The mistake here is presuming that the service drop is to the facility. The actual service drop is to the machine tool. The machine tool is like a freaky house. The buss system is the POLCO.

POLCO??? ...as in the providing electric utility, aka Power Company (POCO or PoCo)?

If your facility's service drops are to each machine or machine system, your facility's service is atypical if not quite rare, IMO. How is this so? I can definitely see where this kind of service could lead to some confusion

 

[hurk27]

This is a little write up I give the guys at work to help them understand the terminology of grounding and how to apply the NEC to each purpose

Basically there is 4 grounding terms we have to deal with in the NEC that confuse many electricians,

Grounded Circuit Conductor NEC Article 200 (sometimes can be called a neutral)
Grounding Electrode Conductor (GEC) 250.62-250.86
Equipment Grounding Conductor (EGC) 250.110-250.126
Bonding Conductor 250.90-250.106 and other articles through out the NEC

Knowing the purpose of each is the secret to understanding the how and why of the NEC requirements.

So let’s look at each one, and find the purpose of each.

Some can serve more then one purpose if allowed by the NEC as you will see:
--------------------------------------------------------------------------
Let’s start with the grounded circuit conductor:
The grounded conductor serves as the return path to the source to complete a circuit, also as a neutral it provides a 0 volt reference point when it is connected as the center point of a center tapped transformer, this is when it is a true neutral.
The NEC requires it to be run with the ungrounded supply conductors of a circuit.

But there are times when it can also serve as an EGC, and/or as a GEC, but this is only allowed ahead of the main service disconnect with the exception of existing ranges and dryers where it can serve as the EGC.

It is intended to have normal mode current on it, that is to say it should have current on it if there is a load on that circuit.
--------------------------------------------------------------------------

Grounding Electrode Conductor:
is a connection thru one or more electrodes to earth to stabilize the voltage of a system to earth, to protect against voltages of a higher source, and to provide a low impedance path in the event of a lightning strike on the system, is not intended to carry current in a normal mode as it is for a grounded circuit conductor, or is it intended to carry fault current.

Now let me expand on this, there is nothing that says it wont carry normal mode current, or fault current, but that is the effect of a conductor serving a dual role such as ahead of the service disconnect. Or as a bond connection to a water pipe that is also the GEC connection, and a fault happens to the water pipe. As we can see there will be many times a conductor will be installed for a given purpose but will criss cross with serving the purpose of other conductors, but for each purpose it must meet or exceed the NEC requirements for each purpose it will serve.
--------------------------------------------------------------------------

Equipment Grounding Conductor:
The purpose is to simply carry a return fault current back to the source to facilitate the opening of the short circuit protection device or circuit.
Again it is not intended to have normal mode current on it. Like the grounded circuit conductor it too is also required by the NEC to be run with the circuit conductors it protects, from the MBJ to the load it serves.
--------------------------------------------------------------------------

Bonding conductor:

Is a conductor that does nothing more then bring two or more conductive surfaces to the same potential, so a difference of potential can not exist between them, it could be a bond between two electrodes as an extension of the GEC, or a bond between two sections of equipments as an extension of the EGC, or it could be neither just an equal potential bond, as used in article 680.
This does not mean it will not carry fault current, nor does it mean it won’t be part of a GEC path way, as in some cases it will serve both.
--------------------------------------------------------------------------

Once we understand each purpose we can apply the NEC for that purpose, and in the case of a conductor serving more then one purpose, make sure it meets the minimum of each requirement.


If I missed anything let me know

 

[don_resqcapt19]

The mistake here is presuming that the service drop is to the facility. The actual service drop is to the machine tool. The machine tool is like a freaky house. The buss system is the POLCO.

There are very very few cases where the NEC would permit the actual service drop to terminate at the machine tool. Where is the meter? Where is the service disconnect? How do the supply conductors get to the machine tool?

 

[don_resqcapt19]

Maybe you can give me a reference to running the EGC from the facility source considering the numerous industrial sites I've been to where the wire you request simply doesn't exist in any shape or form. The EGC originates at the installed buss head that clamps to each of three buss bars and once to the building steel grounding grid in place of a local grounding electrode.

Three buss bars and a buss frame are all there is to attach. It took a lot of research but to my best estimates the plant grounding system is an IT system while the machine tools are a TN-S system.

The progression at my site was
1) Ungrounded Delta (IT) 3-bar
2) Solidly Grounded Wye (TT) 4-bar
3) High-Resistance Wye (IT) 3-bar

Machine tools are all TN-S with the 2nd generation areas using the 4th bar EGC. 1st and 3rd generation use the buss frame exothermically welded to the building steel.

The only difference in the code rules for the use of EGCs in grounded systems and ungrounded systems is the fact that there is not a system or main bonding jumper in an ungrounded system. 250.4(B)(2) requires the EGC to originate at the service equipment and be connected to the GEC at that point.

 

[pfalcon]

(Modified slightly)
Three buss bars and a buss frame are all there is to attach. It took a lot of research but to my best estimates the plant grounding system is an IT system while the machine tools are a TN-S system.

The progression at my site was
1) Ungrounded Delta (IT) 3-bar
2) Solidly Grounded Wye (TT) 4-bar
3) High-Resistance Wye (IT) 3-bar

Machine tools are all TN-S with the 2nd generation areas using the 4th bar. 1st and 3rd generation use the buss frame exothermically welded to the building steel.

Please work from this description. It is true of my site and many others around the city. I want to get all the terminology right.

Sorry about the delay in answering, things got busy here. Sorry about saying POLCO, I mixed IPALCO and PoCo together - Indianapolis Power and Light Company.