Fully encased rebar???

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albion

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I am a commercial contractor who builds municipal pools when available. On a current project we have a situation were the concrete contractor incorrectly placed some "wet stuck" rebar stirrups. These bars are not tied to the rebar mats which are bonded. The intent was to bond these bars with a bare #8 copper. Unfortunately the architect & engineer came up with a rework for the bars which called for them to be cut off flush with the concrete. This was done, now they tell us that the encased rebar stubs must be bonded or removed. My electrical contractor tells me that drilling into the exposed top of the cut-off bar with a self-drilling self-tapping screw and attaching a bonding clip will not meet code. Drilling the bars out of the concrete could cuase damage to other rebar.
The big question is basically, since these #4 rebar stubs are to be subsequently buried in concrete is bonding actually required by code?
Thanks :confused:

[ May 19, 2004, 11:34 AM: Message edited by: don_resqcapt19 ]
 
Re: Fully encased rebar???

In my opinion, the bonding is required.

Quote from 680.26:
(B) Bonded Parts. The parts specified in 680.26(B)(1) through (B)(5) shall be bonded together.
(1) Metallic Structural Components. All metallic parts of the pool structure, including the reinforcing metal of the pool shell, coping stones, and deck, shall be bonded. The usual steel tie wires shall be considered suitable for bonding the reinforcing steel together, and welding or special clamping shall not be required. These tie wires shall be made tight. If reinforcing steel is effectively insulated by an encapsulating nonconductive compound at the time of manufacture and installation, it shall not be required to be bonded. Where reinforcing steel is encapsulated with a nonconductive compound, provisions shall be made for an alternate means to eliminate voltage gradients that would otherwise be provided by unencapsulated, bonded reinforcing steel.
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The tying together of the rebar is one of the many ways the rebar can be bonded. If it is not tied, it must be bonded in another manner. Self drilling sheet metal screws cannot be used, because it would violate 250.8, which states:
250.8 Connection of Grounding and Bonding Equipment.
Grounding conductors and bonding jumpers shall be connected by exothermic welding, listed pressure connectors, listed clamps, or other listed means.
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Re: Fully encased rebar???

the bars are no longer structural components. section cited does not say all metal, but structural and exposed.
 
Re: Fully encased rebar???

Article 100

Structure.That which is built or constructed.

Albion, I wish I could help, but it would seem that since the rebar is installed in the concrete it is part of the structure whether it serves as a functional component or not.

The real issue here is safety, the Equipotential of all the components is necessary to eliminate the possibility of voltage gradients and / or potential differences between any give conductive surface.

The concrete is considered conductive so the rebar being buried in the concrete would not provide safety.

Roger
 
Re: Fully encased rebar???

Originally posted by roger:
Article 100

Structure.That which is built or constructed.

Albion, I wish I could help, but it would seem that since the rebar is installed in the concrete it is part of the structure whether it serves as a functional component or not.

The real issue here is safety, the Equipotential of all the components is necessary to eliminate the possibility of voltage gradients and / or potential differences between any give conductive surface.

The concrete is considered conductive so the rebar being buried in the concrete would not provide safety.

Roger
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Re: Fully encased rebar???

it's true that 250-8 states that sheet metal screws, of any kind, "shall not be used." And, a strict interpretation of 250-8 would force you to expose enough of the rebar end to use a listed clamp or weld. However, it's common practice to bond screen enclosures with a brass or copper lay in connector. the connector is attached with a stainless steel 10-32 screw and nut. I would ask the AHJ for written approval to use a 10-32 SS screw in the rebar end. Drilling and tapping 3/8" of 10-32 thread in the rebar end would take the least man hours, imo.
Just a wild thought, are the rebar stubs less than 4" long? You could ask the AHJ for dispensation under 680.26 (3), "isolated parts."
 
Re: Fully encased rebar???

if everything in a structure is a "structural component", then the term is meaningless.
 
Re: Fully encased rebar???

Nobody is suggesting that everything in a structure is a "structural component." Things are defined by their intended purpose and use. Rebar in concrete serves no other purpose than structural support.
 
Re: Fully encased rebar???

stirrups stuck in wet concrete without any connection to the other rebar are not structural components of the structure. they may be within the concrete but are not components of the concrete structure. and after they have been cut off and nothing is connected to them, they are hardly worth dickering about. they will be buried under concrete, so they will not be surface metal. These pieces are no longer "intended" for anything. This is giving inspection a bad name. This is no different than leaving a loose block of wood in the attic, and calling it a structural component, a hazard, must be nailed to something. It's within the structure, it had been intended for something but is no longer to be used, it is unattached to other structural members.

And conductivity is irrelevant as the requirement is for structural components and other mentioned items. Threaded connections are not sheet rock screws. threaded and bolted (threaded screws) will suffice and are completely legal, or use acorn clamps which are specific listed to bonding buried rebar. :p
 
Re: Fully encased rebar???

Paul, Hmmm, so what you're saying is, we wouldn't have to bond any other metallic items within the pool vicinity if they are not a functional part of the structure. :roll:

Can you please explain this statement
And conductivity is irrelevant as the requirement is for structural components and other mentioned items.
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This would imply we wouldn't need to bond any metal other than the rebar or parts connected to it.

If these stirrups are not bonded and there is a voltage imposed on them from anywhere (possibly a stray voltage from the ground below) you are saying you don't see a potential difference between them and the other bonded items.


Roger

[ May 18, 2004, 04:24 PM: Message edited by: roger ]
 
Re: Fully encased rebar???

not if they are not mentioned, are not part of the structure, and ARE fully encased in the concrete. all the wood screws in the wood deck next to the pool do not need to be bonded either, even though they are metal structural compnents. :p :p
 
Re: Fully encased rebar???

Originally posted by apauling:
not if they are not mentioned, are not part of the structure, and ARE fully encased in the concrete. all the wood screws in the wood deck next to the pool do not need to be bonded either, even though they are metal structural compnents. :p :p
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Paul, these screws are excluded if you read 680.26(B)(3). That doesn't exclude metalic parts beyond the size allowed or penetrating into the structure more than 1" as specified in this section, which I would feel certain that these stirrups exceed.

Roger
 
Re: Fully encased rebar???

Paul please tell, where do you get the idea that the bonding stops at the "reinforcing grid"?

A metal fence post touching the edge of the deck is also not a structural part of the deck, would you not bond it.

Roger
 
Re: Fully encased rebar???

Not sure I really want to get into this one since it's a little heated and I’ve never installed a pool, but…

The heading in 680.26(B)1 says “metallic structural components” and then the text says “all metal parts of the pool structure”. These cut back stirrups IMO are not structural, but are obviously part of the structure. So is “structural component” part still implied in the corresponding text?

The intent of the bonding is described in 680.26(A) Performance. All of this bonding is done to eliminate voltage gradients. If the structure is full of bonded rebar but there are a few small chunks of metal scattered and isolated from the bonded metal, I do not believe there is any voltage gradient issue or any safety issue.

That being said, the way the code text is worded, you would need to ground these abandoned-in-place stirrups if you wanted to get technical.
 
Re: Fully encased rebar???

1. My read on this is that the stirrups are cut off (as ordered by the architect and/or engineer) but then the stirrups are covered in concrete in a later pour. The stirrups will not be exposed when the project is done. Did I read this correctly?

2. Why isn't the architect or engineer required/liable for coming up with an exact solution to remedy this?

3. This is code and safety stuff. No need for anybody to get personal about it. It can be entertaining to watch people get their knickers in a knot but in my opinion it is not productive and brings disrepute to this forum. Please do not take this personally :)
 
Re: Fully encased rebar???

Guys,
I have deleted a number of posts from this thread as they were getting out of hand. Please keep the discussion to the technical merits of the question. Thanks.
 
Re: Fully encased rebar???

Start chipping. (Been there, done that). Ground wire to be connected using at least two split bolts, saddle clamps, etc. UNLESS... the rebar is of the type that comes from the factory with a plastic coating.
As for other stuff, like fence posts: within the distance (is it 10 feet?), it gets bonded. Ditto for handrails, piping, etc- everything except tiny, isolated components such as jet nozzles.
 
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