grounding at detached garage

[JohnJ0906]

Stickboy, what state are you in, and what does this inspector use as back up to his not allowing a 4 wire feeder to an out building?

If there are any conductive parallel paths between these buildings he is causing a potentially dangerous scenario and a NEC violation.

"He may be in for bigger problems in 2008 if the three wire allowance is prohibited."

Not really since AHJ has the final say... :>


I live in connecticut, I don't see the problem, why would you want a fault to travel all the way back to the original service? I think the state electrical inspector and our power supplier, (Connecticut Light & Power) require this install... for example, if I installed a 200a pedastal service I would have a meter with 200a main breaker combo, drive 2 ground rods, bond the neutral to the ground rods, Then pull 3 wires to the house, install a 200a main breaker panel, drive 2 ground rods, again bond the neutral to the ground rods... Bond water etc... call it done... I do the same when I do a remote pool panel also...

This sounds like a violation to me. If the Main breaker i.e. the main service disconnect is outside I would have to pull 4 wires to the house (2 hots, neutral, ground) and NOT bond ground and neutral inside- its a subpanel. I would also have to bond the water to the MAIN, not the panel. I am refering to the example above (200amp pedistal servive) not the original question

 

[stickboy1375]

This sounds like a violation to me. If the Main breaker i.e. the main service disconnect is outside I would have to pull 4 wires to the house (2 hots, neutral, ground) and NOT bond ground and neutral inside- its a subpanel. I would also have to bond the water to the MAIN, not the panel.

it's not a sub-panel, to be a sub-panel it would have to be connected to the same building....
This is the method are poco and state inspector want...so it cannot be a violation....

 

[roger]

it's not a sub-panel, to be a sub-panel it would have to be connected to the same building...

Please tell us where Sub-Panel is defined and where it is mandated that this panel must be connected to the same building to be considered a sub-panel

BTW, Not meaning to put you on a spot, but if Connecticut has adopted the NEC and the AHJ wants to change parts of it, it would need to be formally done at Government levels, which means it is in writing as an amendment, can you provide this information or are you just going by what you have been told?

Roger

 

[roger]

This is the method are poco and state inspector want...so it cannot be a violation....

What makes you think they can't be wrong?

Roger

 

[Gmack]

Roger,
My problem is that there are far more people exposed to danger from the code required parallel paths on the service, but we make a big deal out of it for second buildings. I have an objection to code rules that tell us that the electrons behave differently based on who owns them. This is exactly what the code is saying when it requires parallel paths on the service side, but prohibits them and says they are a serious hazard at second buildings.
Don

There it is.

In fact should a branch neutral hanging out on a 4wire service/feeder to the second buildings GES it will bypass the "service" and "main" and travel on down the road to the sweet spot back home.

Parallel currents.

Take a ungrounded conductor doing the same. Longer trip time and greater fault current levels.

I dont like it.

 

[George Stolz]

Gmack, can you clarify your last post?

 

[iwire]

Not really since AHJ has the final say... :>

Stick that is not really true.

The AHJ can only enforce the legally adopted rules in your area.

If they adopted the NEC in your area without an amendment covering this situation than the AHJ is wrong.

Further even if the AHJ tells or allows an EC to violate the adopted rules the EC is still liable for anything that goes wrong.

If a cop said you can steal and you get caught the fact that a cop said it was OK will not make a bit of difference.

 

[Gmack]

Gmack, can you clarify your last post?

Yes George,

Some of us electricians question the advantage of having stray, faulted currents leaving one buildind [there by passing/exiting] away from its "main" and its "grounded" coductor.

IMO, it would be better if all stray or faulted currents were shunted at each buildings main just like at each buildings "service"

If said building qualifies for a "main" and a "GES" then I call that a "service"

Stray or faulted currents can be incidental or accidental.

With parallel paths they can provide "fulltime current" on a EGC well beyond the main "upstream"

Thats not good.

Longer distances delay trip time and allow greater fault current to "build up".

If a MBJ is installed on a full sized grounded conductor at each building service
then, IMO, It is safer and provides better operation of "tripping" OCD's.

And there could not be stray or faulted curents running back home to another buildings GC/GES upstream.

2cnts.

 

[stickboy1375]

Stick that is not really true.

The AHJ can only enforce the legally adopted rules in your area.

If they adopted the NEC in your area without an amendment covering this situation than the AHJ is wrong.

Further even if the AHJ tells or allows an EC to violate the adopted rules the EC is still liable for anything that goes wrong.

If a cop said you can steal and you get caught the fact that a cop said it was OK will not make a bit of difference.

SO if the AHJ is wrong who has the final say, and why do I call my state inspector if in fact he does not have the final say? this is useless... the NEC is ONLY a GUIDELINE, the AHJ can be wrong.. so WHO is right cause I just wanna ask HIM instead of all the run around....

 

[iwire]

Gmack I have a pretty good idea of how things work as far as OCP operation.

That said I still have no idea the point you are trying to make.

Is it a three wire or four wire feeder you believe is better?

 

[stickboy1375]

Stickboy, niether was I.

You and your inspectors need to read 250.32.



This is nonnegotiable per the NEC.

Roger

Sure it is... who says the NEC is right? And can anyone explain the exact problem with this situation, other than the NEC says you can't...

 

[iwire]

SO if the AHJ is wrong who has the final say, and why do I call my state inspector if in fact he does not have the final say? this is useless... the NEC is ONLY a GUIDELINE, the AHJ can be wrong.. so WHO is right cause I just wanna ask HIM instead of all the run around....

If the NEC is adopted without amendments in your area it is not a guide line, it becomes the law.

An AHJ just like a cop can only enforce the laws that have been accepted.

Now I don't live on a distant planet, I am fully aware that in the real world many inspectors feel that they can change or make rules up as needed.

Also the 'AHJ' is usually not the person you meet on the job, most times the person you meet on the job is just an inspector enforcing the rules for the AHJ.

The AHJ is usually not a person at all but a Govt. body who is charged with adopting the NEC.

 

[Gmack]

Gmack I have a pretty good idea of how things work as far as OCP operation.

That said I still have no idea the point you are trying to make.

Is it a three wire or four wire feeder you believe is better?

3wire.

Thats what the POCO runs around here for 3wire services.

NEC allows us to run 3wire to another building and use GC as per first building if there are no parallel paths.

 

[iwire]

Sure it is... who says the NEC is right?

Forget if it is right or wrong.

If it has been adopted in your area without amendments it is the law.

 

[don_resqcapt19]

[FONT=&quot] I think that the point that Gmack is trying to make is the same one that Bennie made a number of times before his passing. The impedance of the fault return path for a second building with a 3 wire feeder is almost always less than that of a feeder with a 4 wire service. The feeder neutral will almost always be larger than the EGC for that feeder. If you have a 3 wire feeder and a bonding jumper at the second building the ground fault current is carried on the neutral back to the source. If you have an EGC that current is on the EGC back to the service main bonding jumper and then on the neutral to the source. The second path has a higher impedance and will change the opening time for the OCPD. Assuming that the wire sizes in Table 250.122 are adequate, the trip time change should not be of any consequence.
Don
[/FONT]

 

[stickboy1375]

Please tell us where Sub-Panel is defined and where it is mandated that this panel must be connected to the same building to be considered a sub-panel

BTW, Not meaning to put you on a spot, but if Connecticut has adopted the NEC and the AHJ wants to change parts of it, it would need to be formally done at Government levels, which means it is in writing as an amendment, can you provide this information or are you just going by what you have been told?

Roger

Your right on the sub-panel, I got the horse behind the cart again...:> All i'm saying is that I go to all the POCO yearly meetings on "Cut and Reconnect" policys for EC's, and our state electrical inspector is alyways there for Q&A, and usually a good slide show of violations... :> and this was one of the topics that came up, I've been doing this install for a long time now, BUT I will dig up more info for you guys, everyone knows every state is different, and the NATIONAL in NEC means nothing... :> IE: we JUST started using arc fault breakers... go figure... i'm not trying to prove anyone wrong, because I know it is a violation, but I will find out the excact reason behind this...

 

[iwire]

3wire.

Thats what the POCO runs around here for 3wire services.

NEC allows us to run 3wire to another building and use GC as per first building if there are no parallel paths.

Well strangely I agree.

In certain circumstances for remote buildings I believe a 3 wire feeder with it's larger grounded conductor for a fault path is better.

However if there are other bonded metallic paths between the buildings than my opinion quickly changes.

In 2008 the NEC will eliminate the 3 wire option all together, which IMO is ridiculous as long as we get 3 wire services from the POCO.

If a service is safe than a 3 wire feeder to a remote building must also be safe.

 

[stickboy1375]

Stick that is not really true.

The AHJ can only enforce the legally adopted rules in your area.

If they adopted the NEC in your area without an amendment covering this situation than the AHJ is wrong.

Further even if the AHJ tells or allows an EC to violate the adopted rules the EC is still liable for anything that goes wrong.

If a cop said you can steal and you get caught the fact that a cop said it was OK will not make a bit of difference.

How can that be since they gave out the C/O? I don't wanna turn this into a debate but who would I have to call to go over the state electrical inspectors head...?

 

[George Stolz]

Gmack,

While I agree that in many cases the three-wire feeder is preferable, there are certain things you've said I take issue with.

If said building qualifies for a "main" and a "GES" then I call that a "service"

That's a sloppy use of words, and can lead to confusion. An outside feeder to a structure is not the same as a "service." The NEC has defined "services" and there are certain rules that do not carry over to feeders to remote structures fed from the same service.

And there could not be stray or faulted curents running back home to another buildings GC/GES upstream.

Why are you concerned about a fault's interaction with any building's Grounding Electrode System?

 

[George Stolz]

How can that be since they gave out the C/O? I don't wanna turn this into a debate but who would I have to call to go over the state electrical inspectors head...?

His or her boss.

Don't worry about the debate, it's already begun.