Is this legal?

[benaround]

Please cite reference for 1) a conductor sized per 250.66 cannot serve as both a GEC and an EGC, and 2) where a busbar or other forms of GEC connections must be separate from energized equipment.

1) 250.119

2)it is my understanding that we are trying to keep lightning out of such equipment. All of

the engineered busbar type connecting points I have installed were 'not' inside equipment.

3) I don't see where this is helping joey understand the basics, so I'll leave this in your hands.

 

[Smart $]

Smart,

That same lightning event may jump to a metal drain pipe while its at it, but, I would not

call the metal drain pipe a grounding electrode.

True... but it is more true of a local lightning event. Lightning surges can travel on electrical lines (distribution included of course) for miles, and it's generally all solidly connected on the grounding conductors.

I do agree with your lightning path, but, I

do not think that it was designed for that purpose, any more than the drain pipe. JMO.

The problem isn't in the purpose for which it is designed. The problem stems from the code trying to separate the issues of fault grounding and earth grounding. The fact that a conductor is a conductor is a conductor cannot be refuted by any amount of text.

For the record, it was one of the respected members of this Forum that posted the

comment about EGC and GEC are seperate items...

They are separate issues, i.e. fault grounding and earth grounding. The NEC attempts and does a fairly good job at making them separate items. However, current don't really care what the NEC calls a particular conductor. It just uses whatever is available.

There are many other instances besides the example provided earlier. For example, an enclosure securely fastened to structural steel with conductive means. The enclosure is grounded by way of a [fault grounding] EGC and the structural steel is grounded by way of an [earth grounding] GEC. When an local lightning causes an electrical surge on the enclosure, does the current travel on the GEC, EGC, or both? If a fault occurs in and to the enclosure, does the current travel on the EGC, GEC, or both?

 

[Smart $]

1) 250.119

Hmmm... identification of EGC's doesn't get it, IMO.

2)it is my understanding that we are trying to keep lightning out of such equipment. All of

the engineered busbar type connecting points I have installed were 'not' inside equipment.

I do not disagree with the concept, but I do believe that is a design decision, not one required by the NEC.

3) I don't see where this is helping joey understand the basics, so I'll leave this in your hands.

The easiest (or least costly) solution to the situation he presented opens the floor for going beyond basics.

One basic which I do not believe he is fully understanding is that each electrode is not required to have an individual GEC run to the bonding jumper point. Only one GEC is required, and can be splice/tapped/bonded to for individual electrodes.

 

[joeyww12000]

I do understand you can run one grounding electrode conductor to a grounding electrode and then bond the other electrodes together...from the first electrode back to the first means of disconnect where I make the neutral/grounded conductor bond.....that conductor is my GEC.....from the first grounding electrode to other grounding electrodes is bonding jumpers........the situation at the job im at is the installation has been done already... its not existing....the wire just got pulled last week and they do not want to pull out all the wire from the disconnect going into the MDP.....2 sets of 4-350cu.......Im not sure what size the wire used as a EGC is going into the MDP Ill have to look monday....Right now there are parallel paths for objectionable current in all panels fed from the MDP and from the 208/120 transformers......The foreman plans on fixing these things Monday from my knowledge of bonding and grounding......its taken me a week to convince him........the question remains about where to take the waterpipe and building steel grounding electrode conductor......they are bonded together as of now and are terminated at the neutral/grounded conductor lug in the MDP......the grounded conductor is bonded at the disco already....so this is the wrong place for the GEC to be connected......I told him if he cant get the GEC to the disco at least get it of the neutral bar and to the MDP can where the EGC's come in from the Disco....dont you agree this is safer than bonding the neutral/grounded conductor again in the mdp?

 

[Smart $]

...I told him if he cant get the GEC to the disco at least get it of the neutral bar and to the MDP can where the EGC's come in from the Disco....dont you agree this is safer than bonding the neutral/grounded conductor again in the mdp?

Does the MDP have a grounding bus? That's where I'd terminate 'em.

Is it safer? Yes, but by how much depends on the distance between disconnect and MDP, and the amount of neutral current. They all get bonded together anyway, so the only difference is which path(s) the current will take.

 

[joeyww12000]

No theres not a grounding bus, just a ground lug kit......I wouldnt call it a bus, what is you def of a bus?

 

[Smart $]

No theres not a grounding bus, just a ground lug kit......I wouldnt call it a bus, what is you def of a bus?

Any low-resistance (Cu, Al) bar, of any cross-sectional shape, which permits and is designed for termination of multiple conductors, in this case.

The "can" is not a bus.

Just what size MDP are we talking about? You may have stated it earlier or in one of your other posts, but I'm too busy (and lazy) to go in search of...

 

[joeyww12000]

In that case yes there is a bus, it is a 600a MDP

 

[Smart $]

In that case yes there is a bus, it is a 600a MDP

In using the grounding bus as a GEC splicing medium, its cross-sectional area must be equivalent or greater in ampacity compared to the minimum required GEC size. Generally speaking, if its design easily accommodates a GEC(s) sized to Table 250.66, it meets the ampacity requirement.

As for size, I was looking more for the physical size, trying to determine how much gutter space is in the enclosure... whether to combine GEC/EGC issues or remove the GEC issue entirely from the enclosure and make it external. What size grounding conductors were pulled is also a major factor in making that determination. If smaller than req'd GEC size, will it be easier to replace, or run separately external to feeder conduits?