panel penatration

Would anyone call this out?:smiley:


If you are speaking of the ground wire, it is legal here.

Where does that bare EGC go? What is it being used for?BenLegal here … what is legal there?

Look…I am not going to get complicated here…If that is the GEC going to the GE then it is fine…that small hole is designed to have the GEC run out of it.

Since you did not ask anythig other than that and did not reflect on the entire GES…I will only comment on the GE I see leaving the panel…and it is not a problem…does not have to be secured through a connector as it leaves the panel and so on.

From the 2005 NEC

"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.
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."

What this is saying is the GEC is required to be bonded and secured to the enclosure. I am not sure how the practic of using those small holes in the panel enclosure started, but it is not permitted.
There is a good reason for this, that is if lightning or some other high frequency event occurs, the current tends to flow on the “skin” of the conductor and will flash over to the enclosure from the conductor, causing a large arc and most likely cutting right through the conductor which would obviously be a big problem.

There would have to be differential present for it to flash over, the GEC and the panel are assumed to be bonded together as your code states. No problem with that at all unless some other problem exisited too.


I would be VERY interested in elaborating on these " SMALL HOLES" as they were designed into the system from the manufacturer to allow the GEC to enter into the enclosure…has nothing to do with termination in the enclosure.

Your statement regarding the NEC for the continuous GEC is correct…However I would like the article on the ruling in regards to the non-use of the holes…the conductor enters throught them but terminated onto the enclosure buss bar…

Rather than me HUNT this down…I would like to article number that does not allow the enterance of the GEC through these holes provided by the manufacturer.

Thank You in advance

You can only do it if the GEC is #4 or larger since any smaller size requires physical protection (conduit). That requires a connector. If it is metal it needs to be bonded to the cabinet … and the electrode.
I do see the theoretical issue Pierre brings up but I doubt it is really a problem since the wave would hit the busbar and shunt out the fire before the arc really got going. (about a nanosecond later if there was a foot of GEC in the can).

There is a very good explanation of this theory in the Soarse’s Book on Grounding.

An example. Take a GEC and protect it with a metallic raceway, using a suitable clamp around the conductor and the raceway as per 250.64(E). Studies have shown that 93 % of the current will leave the conductor and flow on the raceway surrounding the conductor. That is why the enclosure/raceway needs to be bonded/secured to the conductor where the conductor enters and exits the enclosure/raceway, as it will “flashover” at either of these points. So entering a panel and then traveling to the bus to make the termination is not suitable, the flash will already have occurred.

What the purpose of those small holes is I cannot say. I know that if you were to email one of the manufacturers, they may tell you.

Another note. The study on the characteristics of the current flow explained above was performed not too long ago. Maybe years ago the holes were there for the purpose you explained, as we see in the photo… It is now not permitted. Thats what progress brings us :wink:

In substantiation with 250.64(E)

250.92 Services
(A)(3) Any metallic raceway or armor enclosing a grounding electrode conductor as specified in 250.64(B). Bonding shall apply at each end and to all intervening raceways, boxes, and enclosures between the service equipment and the grounding electrode.


Does the NEC not state the following :

250.64(B) Securing and Protection from Physical Damage.
**Where exposed, a grounding electrode conductor or its enclosure
shall be securely fastened to the surface on which it is
carried. A 4 AWG or larger copper or aluminum grounding
electrode conductor shall be protected where exposed to
physical damage. A 6 AWG grounding electrode conductor
that is free from exposure to physical damage shall be permitted
to be run along the surface of the building construction
without metal covering or protection where it is securely fastened
to the construction; otherwise, it shall be in rigid metal
conduit, intermediate metal conduit, rigid nonmetallic conduit,
electrical metallic tubing, or cable armor. Grounding electrode
conductors smaller than 6 AWG shall be in rigid metal conduit,
intermediate metal conduit, rigid nonmetallic conduit,

Very hard to assume in that picture…if it is like ours…the # 6 AWG ( if that is what it is ) runs from the enclosure into the wall and down to the GE…being SUBJECT to physical damage is BEING defined even more as we speak in each NEC update.

Interesting enough…We are in 2002 NEC…dont see the article your are refering to…:wink:

Also interesting enough…250.64(E) does not refer to apply if no raceway is being used to protect the GEC.

Can we assume as well as not assume the GEC shown here may go into the wall…and not subject to any physical damage…?

My question is…where in the NEC does it state the holes for the GEC are not allowed to be used…I just spoke with Jim Heading at Cutler Hammer and he said the holes were to be used for the GEC and they had not problem with them…so I am confused now…and have used it 1,000’s of times to run the GEC out of…where am I in violation of the CODE other than stating as such?

Anyway…since I am USING the 2002 NEC in VA…and no such definition of “Physical Damage” is defined in the text…is it not subject to the local AHJ’s review and interpritation?

Hmm…I think I spelled that last word wrong…:wink:

Pierre I agree 100% “where a metal raceway is used” but this is unprotected GEC so that wave that would be coming down the unterminated raceway is not present. All the current is flowing on the GEC. The bonding of the GEC will make that arc path fairly unattracive a nanosecond or so after it arrives. I suppose it really depends on the rise time of the transient but a NS is pretty fast.

lightning and transients have very, very fast rise times, that is part if this problem, when it occurs. The type of installation as shown in the picture would cause a flashover, which could generate a lot of energy mostly in the form of heat. The NEC mentions raceways and enclosures in both 250.64(E) and 250.92(A)(3).

Look…we have to be VERY careful here…if we as Electricians expect the HI ( which is what this board is for ) to call out the GEC running through an approved opening listed by the manufacturer ( to whom I spoke with on the phone ) where the NEC says # 6 AWG is allowed…we could cause ALOT of issues for the Home Inspector in their market.

I can bet you EVERY house in VIRGINIA and MARYLAND and NORTH CAROLINA ( well not everyone…thehehe ) has the GEC leaving the panel through the small opening to the side of the SEC knockout…

Since we know EVERY installation is different…we have to stay away from blanket statements…every AHJ is different and I still do not see a “DEFINED” ability to make this statement based on this picture…

Also I am not sure I want the " Home Inspectors" I teach to start quoting Nano-seconds and the potential for Flashover when they are doing a home inspection…lol…What are your thoughts…:wink:

Dang we need to start our OWN electrical board…I am enjoying this :slight_smile:

As Paul pointed out, this is a very common installation here in the lightning capitol of the world and I haven’t heard the reports of problems one would expect if this was a real problem. I see the point you make but lightning must have a slow enough rise time to avoid it.
If you don’t have some kind of air terminal in your home to bring the lightning in on the load side this will be a line side hit anyway. There are lots of parallel paths to that strike so a small fraction will make it back to a house, unless you are the only guy on a very long, single drop from the transformer.
That is one reason why we like to make up the GEC in the meter base. It tends to keep the real nasty stuff outside.


Just to show you how funny some counties can be on this…in one county we bring the GEC to the Meter Cab…in the next county it MUST be bought into the panel itself and NOT the meter cab…

While the NEC states it can be either the Meter Cab or the Panel…and even to the Messenger itself technically…just funny how it changes from area to area…