Supple-who?

[George Stolz]

1.) NEC Section/Paragraph: 250.54, and all that reference it

2.) Proposal Recommends: [revised text]

3.) Proposal: Change the term "supplementary" to "superfluous".

4.) Substantiation: The two terms, "supplemental" and "supplementary" are synonymous in the English language. It would be easier to distinguish between the two concepts if the type of electrode function specified in 250.54 were changed.

Supplemental is generally defined as "compensating for a deficiency", which can be makes sense when applied to the requirement described in 250.53(D)(2).

The function described in 250.54 would be more aptly re-named, as there is no deficiency in the grounding electrode system that this electrode is serving, and often is superfluous in it's nature.

 

[bphgravity]

Re: Supple-who?

I like the proposal, and would lke it better if if supplementary were changed to "super-stupid electrode".

 

[physis]

Re: Supple-who?

Bryan you're kiilin' me.

I'm sorry, I didn't even read your's until I stopped laughing at Bryan's George.

Are you serious about this or is it a weekend kind of thing?

[ July 17, 2005, 04:53 PM: Message edited by: physis ]

 

[iwire]

Re: Supple-who?

Originally posted by physis:
Bryan you're kiilin' me.

Ditto

 

[George Stolz]

Re: Supple-who?

I'm dead serious.

I don't have my heart set on "superfluous", but I don't have access to a thesaurus so it's the best I could come up with off the top of my head--I'd be willing to entertain other terms.

Supplementary or supplemental? Gimme a break! Who let this through in the first place? :roll:

 

[iwire]

Re: Supple-who?

George I am behind you on this one.

250.54 Unnecessary Grounding Electrodes.

Unnecessary grounding electrodes shall be permitted to be connected to the equipment grounding conductors specified in 250.118 and shall not be required to comply with the electrode bonding requirements of 250.50 or 250.53(C) or the resistance requirements of 250.56, but the earth shall not be used as the sole equipment grounding conductor.

[ July 17, 2005, 05:14 PM: Message edited by: iwire ]

 

[iwire]

Re: Supple-who?

A few more changes.

J

 

[George Stolz]

Re: Supple-who?

At first, I agreed with you on your #1 pick, Bob, but there's a problem: If a ground rod is required by the listing of a piece of equipment, then it is necessary to install it.

I mean, machine manufacturers are gonna feel pretty stupid requiring an "unecessary grounding electrode." I'd get laughed into the CMP's trash can with that!

Know what I mean?

 

[George Stolz]

Re: Supple-who?

LOL Bob!

Redundant doesn't sound too bad.

 

[iwire]

Re: Supple-who?

Originally posted by georgestolz:
At first, I agreed with you on your #1 pick, Bob, but there's a problem: If a ground rod is required by the listing of a piece of equipment, then it is necessary to install it.

 

[physis]

Re: Supple-who?

I've been busy doing something else. But with the little bit I've looked at I'm voting "unnecessary electrode".

 

[George Stolz]

Re: Supple-who?

Originally posted by iwire:
]Is there such a machine?

x-ray machines have such reqmts, don't they?

my keyboard is broke. don't drink and type.

hope it dries out...

[ July 17, 2005, 09:23 PM: Message edited by: georgestolz ]

 

[physis]

Re: Supple-who?

don't drink and type.

The new forum motto.

 

[petersonra]

Re: Supple-who?

I will give you my take on this issue.

I suspect that the machine makers know full well that there is no "need" for the extra ground rod.

However, they have discovered that many, especially older, plants have really poor grounding and bonding practices.

It is much easier to tell them to add a ground rod than to fix the plant's power problems.

personally, I think they would be better to tell them to bond it to the building steel as well. that often does seem to have some positive effect. i have not seen that a ground rod really does much, but bonding to the steel in the area (or maybe bonding the steel in the area) does seem to help in some cases.

 

[69boss302]

Re: Supple-who?

supplementary were changed to "super-stupid electrode".

I like Bryan's. I'm now in a place where they drive ground rods to put in drinking fountains just about. They actually make it a requirement for any machine and they don't care about any other grounding means. I have even tried to use comments from this site to convince them it is a waste of money, plus way out of line to not bond to the system ground. The thing's I've been installing I have made sure there is still and EGC pulled in to connect to the machine. It get's real frustrating. Nobody seems to understand that the earth is not a return path for fault current. They are really stuck on just drive a ground rod and your set. I think even the POCO follows this. Maybe after hurricane Emili blows through they'll find out what the ground rod is good for.

One of my guys even just referred to it as a tie down just incase the machine was going to tip over.

 

[physis]

Re: Supple-who?

I think that everybody at the NFPA knows how pointless the super-stupid electrode is. And I don't think there's a snowball's chance of getting the requirement changed. Unless maybe you were interested in adding additional super-stupid electrodes. (that's just fun to say ) The NEC has too many ground-a-holics on the panels.

 

[mc5w]

Re: Supple-who?

Places where supplementary grounding electrodes are required by NEC or good installation practices:

1. NEC 800.100(A)(4)
2. NEC 820.100(A)(4)
3. Grounding of induction heating equipment
4. Grounding of other radio frequency or audio frequency equipment
5. Grounding of CAT scanners
6. The walls of a concrete or metal swimming pool happen to be a supplemental grounding electrode

In the first 2 instances you need a low inductance ground because lightning has both direct current and high frequency alternating current components.

Likewise, a long equipment ground wire tends to be ineffective at audio and radio frequencies - at 1/4 of a wavelength a wire that is grounded at one end is an open circuit at the other. At 1/8 wavelength the wire will act as an almost pure reactance. Likewise, an equipment grounding conductor that is inside of steel conduit just does not work at radio frequencies. For induction heating equipment you most definitely need a local ground rod and to bond to the rebars and mexh in the local concrete slab to prevent tingle voltages.

Similarly, medical equipment manufacturers like to have a low inductance ground for noise control and a conductor that backs up the main grounding electrode conductor for the service.

I have also placed pieces of copper foil underneath rubber floor tile at each electrical receptacle and then bonded to the equipment ground at the receptacle. The electrical inspector asked me what it did and I told him that it was to get rid of static electricity from people. He said, " Oh, the purpose is to protect the equipment from people, not the people from the equipment."

 

[George Stolz]

Re: Supple-who?

Well, now I know what the inside of my keyboard looks like.

One of my guys even just referred to it as a tie down just incase the machine was going to tip over.

Now that's funny!

 

[69boss302]

Re: Supple-who?

Originally posted by georgestolz:
Who are "they"? The AHJ?

The infamous "THEY" No AHJ required. I'm in an industrial manufacturing plant. Many they's that run around and say "codes don't matter here, we're a manufacturing facility, production, production, production!"

I had a Commanding Officer once that wore a t-shirt, with "I AM THEM" printed on it. Anytime anyone mentioned they or them he would open up his shirt, and say "Talk to me". He was actually one of the best CO's I ever had.