Irreversible connections for ufer

[Jerramundi]

In viewing your attachment the connection to the rebar does not have to be irreversible. If it's within the concrete it has to be with a clamp rated for a connection within the concrete.

Just to play devil's advocate for the sake of argument... would you recommend doing an irreversible connection anyway? Even if not required by code? Seems to me like that might be a good idea given the inability to access the connection point in the future.

 

[Carultch]

Just to play devil's advocate for the sake of argument... would you recommend doing an irreversible connection anyway? Even if not required by code? Seems to me like that might be a good idea given the inability to access the connection point in the future.

If it is literally cast in concrete, it is irreversible no matter what hardware you use for accomplishing the connection. Irreversible means that you'd have to permanently damage something to disconnect it, as opposed to a simple unfastening of a screw or bolt that is reversible because it can be re-fastened. Cast a setscrew rebar clamp in concrete, you'd have to cut through the concrete to unfasten it (i.e. an irreversible action), and even then, the concrete stuck in its threads may not allow unfastening it.

 

[Jerramundi]

If it is literally cast in concrete, it is irreversible no matter what hardware you use for accomplishing the connection. Irreversible means that you'd have to permanently damage something to disconnect it, as opposed to a simple unfastening of a screw or bolt that is reversible because it can be re-fastened. Cast a setscrew rebar clamp in concrete, you'd have to cut through the concrete to unfasten it (i.e. an irreversible action), and even then, the concrete stuck in its threads may not allow unfastening it.

I suppose concrete encasement could be considered making a connection irreversible.

But then again, is there no way a connection could fail after concrete encasement? I would imagine there would be as concrete is porous and such allows air and liquid through... and may shift with the soil/Earth.

I was just wondering if you more seasoned commercial vets would do an irreversible connection as defined by 250.64(C)(1) (i.e. irreversible crimp and/or exothermic weld) PRIOR to the encasement... since post encasement, the accessibility is all but eliminated.

I feel like doing an irreversible connection as defined by 250.64(C)(1) prior to encasement would more greatly minimize having to break that concrete up for future maintenance more so than say utilizing a listed mechanical connection. It would explain why some jobs are spec'd this way despite not being required by code for anything but splicing the GEC.

 

[roger]

I was just wondering if you more seasoned commercial vets would do an irreversible connection as defined by 250.64(C)(1) (i.e. irreversible crimp and/or exothermic weld) PRIOR to the encasement... since post encasement, the accessibility is all but eliminated.

No, we just used a connector listed for the purpose, something similar to THIS

Roger

 

[ActionDave]

I was just wondering if you more seasoned commercial vets would do an irreversible connection as defined by 250.64(C)(1) (i.e. irreversible crimp and/or exothermic weld) PRIOR to the encasement... since post encasement, the accessibility is all but eliminated.

Never ever, not once. Never done it and never seen it speced either, and I've been on some jobs with pages of grounding specs.

I feel like doing an irreversible connection as defined by 250.64(C)(1) prior to encasement would more greatly minimize having to break that concrete up for future maintenance more so than say utilizing a listed mechanical connection. It would explain why some jobs are spec'd this way despite not being required by code for anything but splicing the GEC.

There is no future maintenance of a concrete encased electrode. You bug on to the rebar with a piece of copper and a listed lug like Roger linked to and you walk away forever, or for as long as the structure lasts.

 

[brantmacga]

The connection means is likely more clearly defined in the job specs.

I’ve never once seen a spec that requires exothermic or crimped on the CEE.


Sent from my iPhone using Tapatalk

 

[Greentagger]

The connection means is likely more clearly defined in the job specs.

I’ve never once seen a spec that requires exothermic or crimped on the CEE.


Sent from my iPhone using Tapatalk

I have. Many times.

 

[brantmacga]

I have. Many times.

Just curious what type of project?


Sent from my iPhone using Tapatalk

 

[Greentagger]

Mostly larger industrial projects. Airport control towers, hangars, fuel storage . Government projects.

 

[infinity]

I've seen it in job spec's too but it is not an NEC requirement.

 

[Jerramundi]

I'm just a lowly residential dude w/ a few years commercial experience, but I think if it were up to me AND cost effective, I would do the "irreversible connection" as defined by 250.64(C)(1) for the simple fact that the connection point is no longer accessible post pouring the concrete and thus a "stronger" connection would be merited... than if, say, the connection point were accessible for future maintenance.

Whether or not an "irreversible connection" as defined by 250.64(C)(1) is "stronger" than a mechanical connection with a listed connector, I'm not sure. From a purely semantic perspective, the way the code is worded, it sounds like the "irreversible connection" as defined by 250.64(C)(1) would be comparatively "stronger" than a mechanical one.

While I understand and agree with the argument that a CEE could be considered "irreversible" simply by virtue of being a CEE, I can't help but think about the fact that the concrete is porous (i.e. liquid could get in and cause rust) and the concrete could potentially shift with the Earth potentially causing a break.

Although conversely, by that very same logic, a more flexible connection point may be merited. How one would accomplish a "more flexible connection point" is beyond my knowledge.

Just thinking aloud. Not saying anyone is wrong or right. Just some food for thought

 

[infinity]

I'm just a lowly residential dude w/ a few years commercial experience, but I think if it were up to me AND cost effective, I would do the "irreversible connection" as defined by 250.64(C)(1) for the simple fact that the connection point is no longer accessible post pouring the concrete and thus a "stronger" connection would be merited... than if, say, the connection point were accessible for future maintenance.

Whether or not an "irreversible connection" as defined by 250.64(C)(1) is "stronger" than a mechanical connection with a listed connector, I'm not sure. From a purely semantic perspective, the way the code is worded, it sounds like the "irreversible connection" as defined by 250.64(C)(1) would be comparatively "stronger" than a mechanical one.

While I understand and agree with the argument that a CEE could be considered "irreversible" simply by virtue of being a CEE, I can't help but think about the fact that the concrete is porous (i.e. liquid could get in and cause rust) and the concrete could potentially shift with the Earth potentially causing a break.

Although conversely, by that very same logic, a more flexible connection point may be merited. How one would accomplish a "more flexible connection point" is beyond my knowledge.

Just thinking aloud. Not saying anyone is wrong or right. Just some food for thought

I hear what you're saying but think about the fact that you think that an irreversible connection is better (needed) than a mechanical one when the rebar sections are simply tied together with tie wire. Certainly if a twist of tie wire is good enough to make the CEE a wrench tight connector on the GEC is more than adequate.

 

[Jerramundi]

I hear what you're saying but think about the fact that you think that an irreversible connection is better (needed) than a mechanical one when the rebar sections are simply tied together with tie wire. Certainly if a twist of tie wire is good enough to make the CEE a wrench tight connector on the GEC is more than adequate.

That's stunning to me. I would think each piece of rebar should be welded together at a minimum.

Then again I am known for over thinking things and pissing people off in the process ...and not just w/ electrical theory.
I have this uncanny ability to piss off both Democrats and Republicans, but I digress, lol.

 

[roger]

Next time you see a group of "rod buster's" on a job site stop by and tell them you need them to weld the rods together and see how that goes.

Roger

 

[roger]

Think about projects that do not even have CEE's, they aren't that big of a deal and don't need a lot of attention.

Roger

 

[infinity]

That's stunning to me. I would think each piece of rebar should be welded together at a minimum.

Then can be welded together but it's not required. Here's the relevant section:

250.52(A)(3) Concrete-Encased Electrode. A concrete-encased electrode shall consist of at least 6.0 m (20 ft) of either (1) or (2):
(1) One or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm ( 1 ∕ 2 in.) in diameter, installed in one continuous 6.0 m (20 ft) length, or if in multiple pieces connected together by the usual steel tie wires, exothermic welding, welding, or other effective means to create a 6.0 m (20 ft) or greater length; or
(2) Bare copper conductor not smaller than 4 AWG

 

[Dennis Alwon]

The stubbed up rebar is part of the Grounding Electrode.

One can argue that the section that extends out of the concrete is no longer concrete encased electrode because it technically is not in concrete. However, there is a code section that allows us to connect to it.

250.68(C)(3)A rebar-type concrete-encased electrode installed in
accordance with 250.52(A)(3) with an additional rebar
section extended from its location within the concrete to
an accessible location that is not subject to corrosion shall
be permitted for connection of grounding electrode
conductors and bonding jumpers. The rebar extension
shall not be exposed to contact with the earth without
corrosion protection

 

[Jerramundi]

Then can be welded together but it's not required. Here's the relevant section:

With everything that goes into grounding and bonding, I would think steel wire ties would be a no go. Someone must have tested it at some point, or at least I would hope so.

 

[Carultch]

Then can be welded together but it's not required. Here's the relevant section:

They use the specific term exothermic welding. Is there a particular reason for this, and what exactly is the alternative to this kind of welding? I.e. is there a reason other forms of welding don't necessarily qualify?

Based on a broad definition of exothermic as a process converting non-thermal energy into thermal energy, all welding is exothermic in some form or another. The only difference I can think of, is whether the energy source is chemical combustion or electrical.

 

[infinity]

They use the specific term exothermic welding. Is there a particular reason for this, and what exactly is the alternative to this kind of welding? I.e. is there a reason other forms of welding don't necessarily qualify?

Based on a broad definition of exothermic as a process converting non-thermal energy into thermal energy, all welding is exothermic in some form or another. The only difference I can think of, is whether the energy source is chemical combustion or electrical.

It can be exothermic welding (AKA cadwelding) or any other type of welding.