Bonding line through main panel box

[Arthur F. Seifert]

Friends,
Does the ground wire need to pass through a bushing as it exits the panel box to the ground rod? I have one that passes through a small hole in the box (loose and open around wire where it passes through).
Thanks,
Art

[Jim Port]

Some areas do require a Kenny clamp on the conductor. Other areas approve the use of the 1/4" hole into the panel. Still others allow the use of an NM connector.

I have never heard an inspector say what the possible issue would be.

[Robert Meier]

Many panels have a small KO designed specifically for the GEC to enter the enclosure. GEC's do not require bushings even if larger than #6 and in a raceway.

[Arthur F. Seifert]

Thanks guys. I am new to this and didn't know if I should make an issue of it. Your help is greatly appreciated.
Art

[Joseph M. Whitt]

Any time any size Grounding Electrode Conductor passes through a metal raceway it is required to be bonded on each end.

It has been long debated about when it passes through an enclosure such as a panel or meter base. One thing is the ¼ inch holes in the bottom are not for the GEC to pass through. These are drain holes to allow moisture to drain.

Understanding that lightning is a high frequency event helps with the understanding of the bonding requirements. In a high frequency the current traveling through a conductor travels on the outer side of that conductor. Should this conductor pass through something metal the current will jump to that metal.

I have witnessed this event and once on my own meter base where a lightning event caused damage to the GEC as well as the meter base.
I am of the opinion that anytime the GEC passes through anything metal it needs to be bonded just for this reason.

[Robert Meier]

Originally Posted by jwhitt

I am of the opinion that anytime the GEC passes through anything metal it needs to be bonded just for this reason.

Just to clarify Mike's position it is his opinion because the NEC doesn't directly address the issue of when a GEC enters an enclosure when it's not in a ferrous raceway.

[Joseph M. Whitt]

Originally Posted by Robert Meier

Just to clarify Mike's position it is his opinion because the NEC doesn't directly address the issue of when a GEC enters an enclosure when it's not in a ferrous raceway.

Oh but yes it does.

250.64(E) Enclosures for Grounding Electrode Conductors. Ferrous metal enclosures for grounding electrode conductors shall be electrically continuous from the point of attachment to cabinets or equipment to the grounding electrode and shall be securely fastened to the ground clamp or fitting. Nonferrous metal enclosures shall not be required to be electrically continuous. Ferrous metal enclosures that are not physically continuous from cabinets or equipment to the grounding electrode shall be made electrically continuous by bonding each end of the raceway or enclosure to the grounding electrode conductor. Bonding methods in compliance with 250.92(B) for installations at service equipment locations and with 250.92(B)(2) through (B)(4) for other than service equipment locations shall apply at each end and to all intervening ferrous raceways, boxes, and enclosures between the cabinets or equipment and the grounding electrode. The bonding jumper for a grounding electrode conductor raceway or cable armor shall be the same size as, or larger than, the enclosed grounding electrode conductor. If a raceway is used as protection for a grounding electrode conductor, the installation shall comply with the requirements of the appropriate raceway article.

Don't like quoting code here but sometimes it can't be helped

[Chad Norlen, CPI]

Originally Posted by jwhitt

One thing is the ¼ inch holes in the bottom are not for the GEC to pass through. These are drain holes to allow moisture to drain.

http://www.schneider-electric.us/sit.../faq_main.page

Why is there moisture in the load center?

[Robert Meier]

Originally Posted by jwhitt

Oh but yes it does.

Don't like quoting code here but sometimes it can't be helped

Me too so I won't make this a code argument, but in defense of my earlier statement the GEC entering a panel doesn't need to be bonded at the entry point into the panel it just needs to be bonded at some point which it is by the neutral bar being bonded to the enclosure.

I know that Mike and I can argue this all day so I will just leave it there and we can agree to disagree.

[Vince Santos]

This little guy says it should have been bonded where it enters the panel but I tend to disagree.

[Jim Port]

I don't see the panel as a "Enclosures for Grounding Electrode Conductors". Now if the GEC were sleeved in a metallic conduit I would agree with the need for bonding.

[Joseph M. Whitt]

Originally Posted by cnorlen

http://www.schneider-electric.us/sit.../faq_main.page

Why is there moisture in the load center?

Condensation, in most cases the interior and exterior of a panel will see different temperatures and when this happens there will be condensation. Having holes for air to flow will help eliminate this effect.

Look at a metal box such as a device box or a 4 square box. Are these ¼ inch holes found in them there to install a grounding electrode conductor? I would bet they are there for the same reason the holes are found in panels.

[Joseph M. Whitt]

Originally Posted by Jim Port

I don't see the panel as a "Enclosures for Grounding Electrode Conductors". Now if the GEC were sleeved in a metallic conduit I would agree with the need for bonding.

I do not want to get into a debate here but if one was to stick to the letter of the code then a bonding bushing of some sort is required where the conductor passes through an enclosure

Enclosure. The case or housing of apparatus, or the fence or walls surrounding an installation to prevent personnel from accidentally contacting energized parts or to protect the equipment from physical damage.
Informational Note: See Table 110.28 for examples of enclosure types

When we go to this Table we can clearly see that it is addressing such things as junction boxes, motor control centers and panels.
As an electrical inspector I will turn down any installation be it meter base or panel where a grounding electrode conductor leaves the enclosure and is not bonded at that point and I will use 250.64(E) to substantiate my ruling.

Be clear that I am not saying that it should be pointed out while doing a Home Inspection but just arguing that the NEC “does” require it to be done although some will argue that the bonding takes place at the point where it is attached to the neutral or grounding terminal of the meter base or panel.

It is my contention that where the verbiage states “each end” means that the point of attachment at the neutral of a meter base or the terminal bar in a panel is one end and where it passes through the hole of the enclosure is another end of the enclosure and needs to be bonded again.
If the argument that it is bonded at the neutral in the meter base or the terminal bar in the panel could it not also be argued that if it is bonded at one end of the raceway it wouldn’t need to be bonded at the other end?

This bonding is needed due to the effects of eddy currents and how they respond in a high frequency event. If the race way is bonded only on one end then the current will leave the conductor and travel on the raceway and will arc back at the other end which will damage the conductor. I have witnessed this very effect where the #6 was damaged coming out of the ¼ inch drain hole in the meter base as well as a big burn spot on the meter base itself.

This is my last post on the matter. I will leave it to each person to decide how they feel about the issue.

[Arthur F. Seifert]

Thanks again to all of you for your input. Perhaps I will call it out as simply an "improvement" item rather than making an issue out of it.
I find it odd that such a major thing as this can be left to such varied interpretation.
Art