250.52 A (3)

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George Stolz said:
Why remove the option of tying pieces together as currently allowed? Is there a technical substantiation to support the removal?
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The whole code in context with the additional wording would still allow tied pies - except for the piece that stubs out - trying to find a NEC styled wording for it - but needs some work...


From what I've seen the CMPs will turn down a whole proposal for a small piece they didn't like, in a heartbeat. I'd seperate all your different concepts into different proposals so they can decide them ala carte, IMO.
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I was wondering that, and if they might accept many versions and deny some and accept one..... :confused:


I'd say clarification for how much overlap between pieces would be a good idea, but again, is there a technical substantiation or a problem being fixed? I'd think it would be hard to present a case for an existing problem, you know what I mean?
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I think some of the proplems are obvious - as the code lacks any real guidance on the topic - but yes I agree - but am reluctant to dig up volumes of evidence and study for some of the stuff that will be a no-brainer - when I have yet to decide a direction to go in.....
 
e57 said:
I was wondering that, and if they might accept many versions and deny some and accept one..... :confused:
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From what I've seen, when they have multiple proposals for one section, they accept the ones they like, and then at some point in the ROP they write the finished section with principles from all the accepted ones.

For example, there were a heap of proposals regarding 210.12 and parts of 210.52, and IIRC they just presented the finished sections in one of the proposals.

Last go around, I made a couple proposals that combined a couple ideas, and they didn't accept any of them in part, but said they would have accepted a part of them. :roll::)
 
Mark,

Since this has become a lengthy (an now fairly convoluted) thread I request that you repost what you believe is your current edition. I will then close this thread.
 
rbalex said:
Mark,

Since this has become a lengthy (an now fairly convoluted) thread I request that you repost what you believe is your current edition. I will then close this thread.
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Since this topic arose out of a thread of over 300 posts - I hardly see this as long or convoluted.... :roll: (In comparison at least.)

But current edition of this is as follows:
Revised Text:

250.52 A (3) Concrete-Encased Electrode. An electrode encased by at least 50 mm (2 in.) of concrete, located horizontally within and near the bottom or vertically, and within that portion of a concrete foundation or footing that is in direct contact with the earth, consisting of at least 6.0 m (20 ft) of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (? in.) in diameter, or consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 4 AWG. Reinforcing bars shall be permitted to be bonded together by the usual steel tie wires or other effective means. Corrosion protection shall be used for any exposed portions of steel reinforcement bars in wet or damp locations. Such corrosion protection shall be hot-dipped zinc galvanized, or approved electrically conductive permanent coating suitable for the conditions, and done prior to the pouring of concrete, and be continuous from a point at least 2” inside the concrete, and extend to the exposed end. Where copper conductor is used as a concrete-encased electrode, exposed portions of the electrode shall comply with 250.64(B), and may be used as a grounding electrode conductor if complying with 250.64(A) through (F). For purposes of 250.68 (A), the exposed portion of the electrode shall be considered part of the concrete-encased electrode for it entire length, if continuous to the qualifying portion(s). Connections to any exposed portion of concrete-encased electrode (copper conductor or reinforcing rods) shall comply with 250.70. Where multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the grounding electrode system.
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Substantiation:
Adds guidance for corrosion protection for exposed steel reinforcement bars if used as the material for the electrode.

Current wording of 250.52 (A) 3 is in direct conflict with 250.68 in many interpretive views that regard exposed portions of the concrete-encased electrode as a non-qualifying location for connection to the concrete-encased electrode. The revised text clarifies this possible conflict that may otherwise place the connection to the concrete-encased electrode beyond inspection or repair unnecessarily if interpreted in this method.

The revised text also clarifies use, connection to, and installation of copper conductor as a concrete-encased electrode. As well as, its popular dual use of the un-encased portion as both a grounding electrode, and grounding electrode conductor. Which may be superior in that it provides no point of connection failure, and lower impedance. As well clarifies that copper conductor, if used as the concrete encased electrodes need not be continuous, and may be connected as would be allowed in 250.68(A). and 250.70.
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Anyway there have been some changes to the wording and I would like some more time for comment on these if possible. Additionally I am currently putting together wording for an addition to 250.53 that I will start another thread on soon.
 
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