250.64(C) GEC irreversible splices - why?

[EBQ]

250.64(C) "GEC's shall be installed in one continuous length without a splice or joint except as permitted in (1) and (2)
  (1) Splicing shall be permitted only by irreversible compression-type  connectors listed as grounding and bonding equipment or by the  exothermic welding process.

What's the reasoning behind the irreversible connectors requirement for the GEC? Is it to prevent tempering or to ensure proper surge current passage? Would a split bolt, acorn, or screw lug style connector work the same from a physics perspective? thanks

 

[roger]

250.64(C) "GEC's shall be installed in one continuous length without a splice or joint except as permitted in (1) and (2)
  (1) Splicing shall be permitted only by irreversible compression-type  connectors listed as grounding and bonding equipment or by the  exothermic welding process.

What's the reasoning behind the irreversible connectors requirement for the GEC? Is it to prevent tempering or to ensure proper surge current passage? Would a split bolt, acorn, or screw lug style connector work the same from a physics perspective? thanks

Any connector properly installed will perform it's purpose from a physics perspective however, an irreversible connection is supposed to be just that which is permanent.

Roger

 

[electrofelon]

250.64(C) "GEC's shall be installed in one continuous length without a splice or joint except as permitted in (1) and (2)
  (1) Splicing shall be permitted only by irreversible compression-type  connectors listed as grounding and bonding equipment or by the  exothermic welding process.

What's the reasoning behind the irreversible connectors requirement for the GEC? Is it to prevent tempering or to ensure proper surge current passage? Would a split bolt, acorn, or screw lug style connector work the same from a physics perspective? thanks

There is no reason. It's just one part of the continued over emphasis in the importance of grounding

 

[kwired]

There is no reason. It's just one part of the continued over emphasis in the importance of grounding

Which may not be as important as some want to think it is. Bonding is definitely important though.

 

[don_resqcapt19]

Because for some unknown reason CMP 5 seems to think that a GEC is more important than an EGC. It is my opinion that the EGC is far more important than the GEC.

 

[infinity]

Because for some unknown reason CMP 5 seems to think that a GEC is more important than an EGC. It is my opinion that the EGC is far more important than the GEC.

I agree, the system would work just fine with no electrodes or GEC's as long as the main bonding jumper was in place.

 

[EBQ]

Does the GES even do anything meaningful locally for surge currents? when service neutral already provides a lower resistance path to absorb excess voltage and is bonded to earth at the transformer.

Other than bonding earth to metal to equalize potentials, what else does a GES accomplish?

 

[kwired]

Does the GES even do anything meaningful locally for surge currents? when service neutral already provides a lower resistance path to absorb excess voltage and is bonded to earth at the transformer.

Other than bonding earth to metal to equalize potentials, what else does a GES accomplish?

It just adds one more electrode to a large network of electrodes.

 

[EBQ]

It just adds one more electrode to a large network of electrodes.

So it's really insurance for the whole, rather than the individual, at least as it relates to a surge.

 

[kwired]

So it's really insurance for the whole, rather than the individual, at least as it relates to a surge.

mostly yes.

Now inspectors seem to be trained to think a missing GEC is the worst possible thing that can happen, and occupants of a building without one are certain to die because of it, reality is it is not.

 

[ActionDave]

So it's really insurance for the whole, rather than the individual, at least as it relates to a surge.

I don't even think it does that. It references one point in the electrical system to earth and 0 V intentionally and if that doesn't happen you end up with a rats nest of unintentional "faults" over your building, neighborhood, county and so on.

 

[kwired]

I don't even think it does that. It references one point in the electrical system to earth and 0 V intentionally and if that doesn't happen you end up with a rats nest of unintentional "faults" over your building, neighborhood, county and so on.

The potential on your secondary circuit is only between your service disconnect and the source, and any secondary distribution pedestals or similar that may also have an electrode. But yes the voltage drop on primary neutral still presents some voltage to earth on your grounded service conductor, and some primary current can flow through your service neutral, and through any ground path it may find on your premises, whether you have a GES or not.

 

[don_resqcapt19]

I don't even think it does that. It references one point in the electrical system to earth and 0 V intentionally and if that doesn't happen you end up with a rats nest of unintentional "faults" over your building, neighborhood, county and so on.

The connection to an electrode doesn't make the voltage on the service grounded conductor, as measured to earth, zero. It just raises the voltage for a small area of the earth around the electrode to the voltage on the service grounded conductor.

 

[al hildenbrand]

The origin of the wording in 250.64(C) is old.

It predates nonmetallic piping systems and supplemental grounding electrodes.

It predates most rural electrification.

It is my opinion that the language reflected the (then) most common installation of a GEC being only a conductor going to a metallic water pipe system supplied by a metallic municipal water system. In the event of a loss of continuity in the grounded service conductor, the water piping-to-neighbors premises wiring system would mitigate voltage swings under load.

Maybe its time to relax this "irreversible connection" requirement given the increasing prevalence of nonmetallic systems in new construction?

 

[ActionDave]

The potential on your secondary circuit is only between your service disconnect and the source, and any secondary distribution pedestals or similar that may also have an electrode. But yes the voltage drop on primary neutral still presents some voltage to earth on your grounded service conductor, and some primary current can flow through your service neutral, and through any ground path it may find on your premises, whether you have a GES or not.

The connection to an electrode doesn't make the voltage on the service grounded conductor, as measured to earth, zero. It just raises the voltage for a small area of the earth around the electrode to the voltage on the service grounded conductor.

I understand all that. The point I was wanting to make is that it's easier to intentionally ground your electrical system than it is to let time and nature take its course or to try and keep it isolated.

 

[shortcircuit2]

250.64(C) "GEC's shall be installed in one continuous length without a splice or joint except as permitted in (1) and (2)
  (1) Splicing shall be permitted only by irreversible compression-type  connectors listed as grounding and bonding equipment or by the  exothermic welding process.

What's the reasoning behind the irreversible connectors requirement for the GEC? Is it to prevent tempering or to ensure proper surge current passage? Would a split bolt, acorn, or screw lug style connector work the same from a physics perspective? thanks

The reason is because of Larry, the Cable Guy. He would always loosen the burndy to insert his ground wire and wasn't talented enough to tighten it back up. So the rule was changed to irreversible and that ended the problem.

 

[kwired]

I understand all that. The point I was wanting to make is that it's easier to intentionally ground your electrical system than it is to let time and nature take its course or to try and keep it isolated.

That I can agree with, but for services, if incoming is already a grounded system, does it really matter if you ground it one more time?

 

[ActionDave]

That I can agree with, but for services, if incoming is already a grounded system, does it really matter if you ground it one more time?

No, it doesn't, but I think we're outnumbered by those that think it does.

 

[EBQ]

The reason is because of Larry, the Cable Guy. He would always loosen the burndy to insert his ground wire and wasn't talented enough to tighten it back up. So the rule was changed to irreversible and that ended the problem.

But Larry would loosen the GEC to GE connector to insert his ground wire all the same