does it matter which GE you go to first?

[sheldon_ace]

hey guys, i am a newbie here.

I recently had an inspector gig me on going to building steel first,(a pier column that was effectively grounded)which was bolted and welded together to the rest of the steel, with my full size GEC (1/0 for 500mcm service). About a 150 ft away was my incoming water main. I came off of the closest steel pier column to the water main with a full size GEC to the building side of the water, then bypassed the meter to the street side. From that same pier column I ran a #6 to two ground rods outside. The inspector said that the steel could not be used as a grounding conductor, and the GEC had to run unspliced to the water main first, which he called my "main grounding electrode". He couldn't give me an exact location in the code that could support his idea. Any input from professionals would be greatly appreciated. I have run into too many inspectors who really aren't qualified to do their jobs....

 

[hey_poolboy]

Re: does it matter which GE you go to first?

Welcome aboard!
I don't know of any reference as to an order in which they must be landed upon, just that they all must be used if available. 250.50.

250.53 C speaks of the bonding jumper(s) used to connect to the electrodes, but says nothing of the order.

Since you are actually maiking a system as described in 250.53 C it should not matter where in that system you make your connection.

Mike

[ July 18, 2005, 08:58 PM: Message edited by: hey_poolboy ]

 

[physis]

Re: does it matter which GE you go to first?

250.64(F)

Edit: There's no such thing as a "main grounding electrode".

Edit: He couldn't give "any" location in code because it's not a code.

[ July 18, 2005, 09:20 PM: Message edited by: physis ]

 

[mc5w]

Re: does it matter which GE you go to first?

250.104(D)(3) permits using the building steel as ground bus for separately derived systems. I cannot find anything that permits use of building steel as a ground bus for the service grounding electrode system or which prohibits such use.

One part of Article 250 allows the frame of a machine or lighting tower to be used as an equipment grounding conductor but another part prohibits the use of building steel as the sole equipment grounding path.

At 150 feet away from the service the building steel is probably a better grounding electrode conductor than say 500 KCM copper. However, if the water service is pretty substantial and is required to be in metal pipe because it runs fire sprinklers, I would run copper wire to it.

Incidentally, you are still allowed to use sprinkler piping that is more than 5 feet from the water service for a service ground provided that the piping is exposed ( no insulation, drywall ) and the building is commercial or industrial.

 

[mc5w]

Re: does it matter which GE you go to first?

From a lightning protection standpoint you do need a grounding electrode as close as practicable to a service switch and with the conductor in as straight a line as practicable.

Also, some utilites required a dedicated ground rod for meter sockets so that the lightning arrestors in electronic meters will work right.

Other than that, I would go to the closest or either the building steel or the water service first.

Also, water services that are done in water main grade pipe make for a bad grounding electode because the outside of the pipe has insulating paint to protect it from corrosion both in transit and when buried. Also, water main pipe joints that use an O-ring and an O-ring retaining clamp are not necessarily electrically continuous.

 

[hurk27]

Re: does it matter which GE you go to first?

If this was a Separately Derived System then one could say the closest electrode is the main one. (250.30(A)(4) but other than that.
There is no such wording in the NEC,

I was going to use the handbook illustration but it shows the GEC hitting the waterline first

 

[physis]

Re: does it matter which GE you go to first?

By mc5w:

I cannot find anything that permits use of building steel as a ground bus for the service grounding electrode system or which prohibits such use.

250.50 Grounding Electrode System. .....................Each item in 250.51(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. ...................

100 Bondidng (Bonded). The permanent joining of metalic parts to form an electrically conductive path that ensures electrical continuity and the capability to conduct safely any current likely to be imposed.

Edit; I thought I'd add the Name of section 250.50

[ July 19, 2005, 02:13 AM: Message edited by: physis ]

 

[sheldon_ace]

Re: does it matter which GE you go to first?

I failed to mention how the said "inspector" wanted me to fix my "error".....

From the first point of bonding to steel, he wanted me to run a 1/0 to the second point of bonding to steel. When I asked him which connection he would prefer (high pressed connectors or exothermic welds)
he said, "Just use split bolts and cover them with green tape."

I almost lost it. He tells me my installation is unsafe because, "if they ever remove a piece of steel, your gounding system is compromised". If they remove a piece of steel, a compromised grounding system is the least of their worries, because that building is coming down!!!!!

Thanks for your insight guys, and I am glad I am not going crazy, I thought maybe I had forgot how to interpret the code.

 

[George Stolz]

Re: does it matter which GE you go to first?

Sheldon, welcome to the forum!

Show him some pictures, the guy might get the impression that he's wrong.

Since there is no text regarding going to the water pipe first, showing him a picture depicting that minor detail will not hurt Sheldon's case any. Let him prove it. He will fail.

[ July 19, 2005, 07:58 AM: Message edited by: georgestolz ]

 

[derf48]

Re: does it matter which GE you go to first?

Your installation is not only correct, but above the minimum set forth in the code. Section 250.64 (F)...A grounding electrode conductor shall be permiitted to be run to any convenient grounding electrode available in the grounding electrode system, or to one or more grounding electrode(s) individually, ... Of course you must still bond all grounding electrodes present per 250.50 together according to 250.53 to make a grounding electrode system.

Fred Bender

 

[physis]

Re: does it matter which GE you go to first?

By sheldon_ace:

Thanks for your insight guys, and I am glad I am not going crazy, I thought maybe I had forgot how to interpret the code.

I've had run ins over this with both EC's and inspectors. I thought maybe it was me too. I think it's rather common. I don't know if it's just that it used to be done that way and some folks still think that's the rule, misinterpretation of the code or both.

 

[sheldon_ace]

Re: does it matter which GE you go to first?

I think this topic needs more insight and maybe a code amendment to explain that it is legal to use the building steel as a grounding conductor. I have had discussions with a few electricians who think that effectively grounding steel means to drive a ground rod and exothermically weld the bare copper to the steel. They don't understand that since the bolt pattern embedded in the footer for the steel pier column is a much better ground than lets say 50 ground rods pounded into the dirt....Wouldn't you agree???

[ July 20, 2005, 07:09 PM: Message edited by: sheldon_ace ]

 

[physis]

Re: does it matter which GE you go to first?

I don't know, "50", that would be a lot of surface area. You could calculate it.

Edit: 65 1/2 square feet for 50 5/8" x 8' rods.

And copper's a better conductor than concrete.

[ July 20, 2005, 08:13 PM: Message edited by: physis ]