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#180939 - 09/17/08 09:22 AM Galvanized ground rods
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
About a year ago IAEI magazine was touting some new galvanized ground rod (basically a planted story and a paid ad). This month they have an article trashing them. Their tests predict you may only get 10 years out of one.
Their credibility is wearing pretty thin with me.
We really need to separate the manufacturers from the code making and code enforcing community.
_________________________
Greg Fretwell

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#180941 - 09/17/08 09:51 AM Re: Galvanized ground rods [Re: gfretwell]
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
I have not read the article to which you refer, but I'd like to point out:

You have never been required to use a special rod as a ground rod. The NEC details pipe, rod, and other made electrodes. There's no reason even a simple piece of #5 rebar can't be used as your electrode.

What the NEC has specified is that rods smaller than the code specified size need to be listed as such. That is, smaller than the 5/8 the code calls for. That's why the galv rod makers passed out those little 'gages.'

Corrosion of ground electrodes has been looked at recently, and there have been plenty of unhappy surprises. It seems that, in very many ordinary situations, the performance and life of the rods and plates is a lot less than was expected. In some reports, the absolute worst results were from ... big surprise here ... rods made of stainless steel. Oops.

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#180942 - 09/17/08 09:59 AM Re: Galvanized ground rods [Re: renosteinke]
dougwells Offline

Member

Registered: 05/03/03
Posts: 1228
Loc: kamloops BC Canada
If we use a ground rod in Canada it has to be listed.

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#180956 - 09/17/08 05:12 PM Re: Galvanized ground rods [Re: dougwells]
brsele Offline
Member

Registered: 07/29/08
Posts: 88
Loc: Northern Ontario
 Originally Posted By: dougwells
If we use a ground rod in Canada it has to be listed.


Really?
I've never noticed any special markings on any rods or plates I've installed.
Do you have a code reference?

Thanks... Bruce

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#180958 - 09/17/08 05:24 PM Re: Galvanized ground rods [Re: brsele]
dougwells Offline

Member

Registered: 05/03/03
Posts: 1228
Loc: kamloops BC Canada

10-700 Grounding electrodes (see Appendix B)

(1) Grounding electrodes shall consist of

(a) manufactured grounding electrodes;
(b) field-assembled grounding electrodes installed in accordance with this Rule; or
(c) in-situ grounding electrodes forming part of existing infrastructure as defined in this Rule.

(2) Manufactured grounding electrodes shall

(a) in the case of a rod grounding electrode, consist of 2 rod electrodes (except for a chemically charged rod electrode where only one need be installed) spaced no less than 3 m apart,

(i) bonded together with a grounding conductor sized in accordance with Table 17; and
(ii) driven to the full length of the rod; or

(b) in the case of a plate electrode, be

(i) in direct contact with exterior soil at no less than 600 mm below grade level; or
(ii) encased within the bottom 50 mm of a concrete foundation footing in direct contact with the earth at not less than 600 mm below finished grade



appendix B

D
Rules 10-700(1)(a), 10-700(4)

Manufactured grounding electrodes are those manufactured and certified to CSA C22.2 No. 41.
It is important that in-situ grounding electrodes provide an equivalent surface area contact with earth as do manufactured electrodes (see CSA C22.2 No. 41). Consideration should also be given to the effects that corrosion may have on the in-situ ground electrode impacting durability and life-expectancy. For example, an underground metal water piping system located at least 600 mm below finished grade and extending at least 3 m has traditionally been recognized as a suitable grounding electrode. Similarly, the metallic reinforcement of a concrete slab, concrete piling, or concrete foundation and iron pilings in significant contact with earth at 600 mm or more below finished grade have also been found to be suitable in-situ electrodes.
Any metallic material encapsulated with a non-conductive compound to protect it from corrosion would not meet the criteria for use as in-situ ground electrode.




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#180961 - 09/17/08 05:51 PM Re: Galvanized ground rods [Re: dougwells]
brsele Offline
Member

Registered: 07/29/08
Posts: 88
Loc: Northern Ontario
Thank you for the info.
I guess that's one of the differences between the CEC and the OESC.

Cheers... Bruce

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#180969 - 09/17/08 07:21 PM Re: Galvanized ground rods [Re: brsele]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
The Local IAEI has had a lot of conversations about rods too. The consensus is all of them rot out pretty quick down here. I was really surprised that anyone would even consider galvanized.
I know right after I moved in here I was fixing a piece of 12ga Romex going out to the dryer in the garage and I buried THWN/EMT. About 2-3 years later I had cause to dig it up. The EMT was just a rusty trail in the sand with little chunks of rusty metal in it.
Right now our defacto ground electrode is a ufer.
_________________________
Greg Fretwell

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#180981 - 09/17/08 10:30 PM Re: Galvanized ground rods [Re: renosteinke]
Elviscat Offline
Member

Registered: 08/13/05
Posts: 214
Loc: Seattle Washington USA
 Originally Posted By: renosteinke

Corrosion of ground electrodes has been looked at recently, and there have been plenty of unhappy surprises. It seems that, in very many ordinary situations, the performance and life of the rods and plates is a lot less than was expected. In some reports, the absolute worst results were from ... big surprise here ... rods made of stainless steel. Oops.



How does this work? do the alloying metals in the SS make it more prone to galvanic action than regular or galvinised steel?

How soon until we need catodic protection systems with sacrificial anodes to go with our ground rods?

Personally, I've always been of the opinion that ground rods don't provide an adaquate path to ground regardless of state of decomposition.

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#180983 - 09/18/08 12:54 AM Re: Galvanized ground rods [Re: Elviscat]
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
 Originally Posted By: Elviscat

How does this work? do the alloying metals in the SS make it more prone to galvanic action than regular or galvinised steel?

How soon until we need catodic protection systems with sacrificial anodes to go with our ground rods?

Personally, I've always been of the opinion that ground rods don't provide an adaquate path to ground regardless of state of decomposition.


Bear in mind Will, that there are over 90 types(grades) of Stainless available.
One thing that has to also be remembered about stainless, is the fact that it contains a fair amount of Nickel and Chromium, Nichrome wire is used for heating elements.

Down here in damp New Zealand, earth electrodes can have a very short life, especially near the coast.
As an inspector, the Earthing test is often the first to be done when checking out faults.
Our supply system depends on good earthing, to clear faults on the system, with reasonably large fault currents being sent down the Earth circuit, back to the transformer.

I have, before today buried heavy copper wire in the soil as an alternative to an actual stake in the ground, where the soil is too stony to get an effective earth.

Some people over here (even some electricians) have the tainted idea that an earth electrode should last the life of the building.
Umm, no, it might if your soil has a neutral pH, but these are few and far between.

In a totally safe building, there should be no current flow in the earth electrode at all, this is not achievable, there will always be a small amount of current flow there, this is what causes galvanic corrosion, to a degree.

The other part is the fact that the metal-soil contact area, is often not a 100% thing due to stones and other larger particles in the soil.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

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#180986 - 09/18/08 08:03 AM Re: Galvanized ground rods [Re: Elviscat]
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
All I can do is report the results .... I can't claim to 'know' why.

One theory that has been advanced is that, as with aluminum, the presence of oxygen is necessary for the formation of a rust-stopping oxide film, and that the lack of oxygen prevents this film from forming. Naturally, then, something else needs to be there to react with the metal, if not oxygen.

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