Two switchboards

[david]

Once an exception to more than one service allowance is met, there is no code violation in relationship to the location of the service disconnects, no matter how far apart those disconnects are located from each other

Both service will be required to bond to the buildings grounding electrodes to establish a grounding electrode system.

In this particular thread it has not been explained why two services are being (designed) installed,

it may be possible to redesign and install one lateral to the building in with a line side tap for the fire pump to a location for the pump service disconnect

Without using arbitrary enforcement of objectionable current there is no code violation

 

[hhsting]

Once an exception to more than one service allowance is met, there is no code violation in relationship to the location of the service disconnects, no matter how far apart those disconnects are located from each other

Both service will be required to bond to the buildings grounding electrodes to establish a grounding electrode system.

In this particular thread it has not been explained why two services are being (designed) installed,

it may be possible to redesign and install one lateral to the building in with a line side tap for the fire pump to a location for the pump service disconnect

Without using arbitrary enforcement of objectionable current there is no code violation

Exterior swbd is 800A 480/277V three phase. Does not have separate line side enclosure to tap from.

From what I understand from this thread concern is that oncw you have GEC to GES, neutral current can flow to the GEC to GES if path is of low resistance. If GE is bldg steel or Ufer then that steel have neutral currents since nutral goes back to same utiltiy transformwr and if high enough cause people to get shock. Or if equipment is bonded to building steel and path still low resiatance then neutral current can flow from steel to the equipment and high enough may cause fire. However this can happen with one service and multiple service diaconnects.


Also, fire pump another service is permitted exception to the rules of 230. Hard to enforce someone with one service and line side tap for FP. Big statement will be shot back NEC allows another service for FP. However still the FP service disconnect can be remote.

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[electrofelon]

If you read closely nec 2017 handbook 230.72(b) commentary water pump is not same as fire pump of Article 695.



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interesting. I noticed that and was wondering about the difference between water pump and fire pump.

 

[hhsting]

interesting. I noticed that and was wondering about the difference between water pump and fire pump.

I think Water pump used to pump water other than fire purposes. Fire pump used to pump water for fire. Not sure.

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[hhsting]

Exterior swbd is 800A 480/277V three phase. Does not have separate line side enclosure to tap from.

From what I understand from this thread concern is that once you have GEC to GES, neutral current can flow to the GEC to GES if path is of low resistance. If GE is bldg steel or Ufer then that steel have neutral currents since neutral goes back to same utiltiy transformer and if high enough cause people to get shock via return path of metal pipes, conduit or equipment somehow bonded to steel, metal underground water pipe or some other method Or if equipment, conduits metal is bonded to building steel and path still low resistance then neutral current can flow from steel to the equipments, conduits metal and high enough may cause fire. However this can happen with one service and multiple service disconnect Or with one service one serive disconnect means if you have bdlg steel or Ufer or metal underground water pipe as electrodes.


Also, fire pump another service is permitted exception to the rules of 230. Hard to enforce someone with one service and line side tap for FP. Big statement will be shot back NEC allows another service for FP. However still the FP service disconnect can be remote.





Edited:

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[hhsting]

Exterior swbd is 800A 480/277V three phase. Does not have separate line side enclosure to tap from.

From what I understand from this thread concern is that once you have GEC to GES, neutral current can flow to the GEC to GES if path is of low resistance. If GE is bldg steel or Ufer then that steel have neutral currents since neutral goes back to same utiltiy transformer and if high enough cause people to get shock via return path of metal pipes, conduit or equipment somehow bonded to steel, metal underground water pipe or some other method Or if equipment, conduits metal is bonded to building steel and path still low resistance then neutral current can flow from steel to the equipments, conduits metal and high enough may cause fire. However this can happen with one service and multiple service disconnect Or with one service one serive disconnect means if you have bdlg steel or Ufer or metal underground water pipe as electrodes.


Also, fire pump another service is permitted exception to the rules of 230. Hard to enforce someone with one service and line side tap for FP. Big statement will be shot back NEC allows another service for FP. However still the FP service disconnect can be remote.





Edited:

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Would this be decent proposal to the panel??:

All metal equpiments, conduits other than service equipment or separately derived system service equipment bonded to bldg steel, underground metal water pipe, shall be installed with high resistance one way device i.e diode such that currents can flow equipment to the electrodes but not the opposite way.

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[hhsting]

Would this be decent proposal to the panel??:

All metal equpiments, conduits other than service equipment or separately derived system service equipment bonded to bldg steel, underground metal water pipe, shall be installed with high resistance one way device i.e diode such that currents can flow equipment to the electrodes but not the opposite way.

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Would this be decent proposal to the panel??:

All metal equpiments, conduits other than service equipment or separately derived system service equipment bonded to bldg steel, underground metal water pipe, shall be installed with high resistance one way device i.e diode such that currents can flow equipment to the electrodes but not the opposite way.

Or language could be:

All service equipment or separately derived system GE shall be installed with high resistance one way device .ie. diode such that currents can flow from service equipment to the electodes but not the opposite way

Edited:

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[Wire-Smith]

No.


The problem I'm talking about is AC first of all. second, the problem would exist without any GES at all. The problem is bonding a system in two locations with other conductive material between the bonds that you don't want current on, you effectively are using "ground" as your current carrying neutral in the part of the building in between and around the bonds.

 

[hhsting]

No.


The problem I'm talking about is AC first of all. second, the problem would exist without any GES at all. The problem is bonding a system in two locations with other conductive material between the bonds that you don't want current on, you effectively are using "ground" as your current carrying neutral in the part of the building in between and around the bonds.

I have 22 feet between the two service discos and they are suppose to have MBJ by code.
I said in nutshell your ground would carry neutral thru in between metal conduits, in between metal equipment thru GES to service disco to MBJ back to utility. If not then I am lost.

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[Wire-Smith]

In my opinion and I've never heard an argument against this opinion. If disconnects are beside each other, the ground current will not cause any problems because there's nothing like gas lines, water lines, EGGs, etc. In between them for the current to cause a problem.


Another option that I gave earlier is a premises isolation xfmr on the system with neutral load before any neutral loads and only bond that secondary at one location.

Another possible option, you have to ask AHJ for special permission for is bonding at utility xfmr only and running EGGs with the service and installing surge arresstors at the premises( they would be called supply side bonding jumpers not EGC and sized as such ,but tomato potato)

 

[packersparky]

If you read closely nec 2017 handbook 230.72(b) commentary water pump is not same as fire pump of Article 695.



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Regardless of what the handbook says, 230.72(B) in the NEC clearly states "fire pumps".

 

[hhsting]

In my opinion and I've never heard an argument against this opinion. If disconnects are beside each other, the ground current will not cause any problems because there's nothing like gas lines, water lines, EGGs, etc. In between them for the current to cause a problem.


Another option that I gave earlier is a premises isolation xfmr on the system with neutral load before any neutral loads and only bond that secondary at one location.

Another possible option, you have to ask AHJ for special permission for is bonding at utility xfmr only and running EGGs with the service and installing surge arresstors at the premises

Ok 230.72(B) fire pump service disconnect is allowed to be remote than normal service disco.

All service discos need MBJ.

My point and hunch based on what was said earlier is FP motor is 3 phase balanced load and possibly no neutral current thus even if far away who cares.
However, this would mean their is no single phase fire pump motors used in industry. If their is then it would defeat the hunch carrying neutral.

However, I would like to know what is the reason behind if disconnects are grouped then ground current wont be an issue gas lines, pipes, conduit???

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[Wire-Smith]

The ground current would just be local of the areas where the main bonds are, it takes more than just ground current to be a problem, if there is nothing in that area for ground current to cause a problem, there is no problem.

When you put them on opposite sides of the building, current will be on every grounded surface in the building, so your more likely to have that added variable that makes ground current a problem, like ground current on a gas line that has a break and the ground current arcs across it, or a water line and someone takes a shower and the current flows through from the shower head to the drain, or you have high neutral currents and few ground paths except say some flexible conduit that slightly rubs against a metal object in that path and it's a poor connection and when you have high neutral loading the poor connection sparks or someone gets in between the connection, or an electrician disconnects a #12egc and gets shocked. Or you lose your neutral from your service on your neutral loaded panel, your entire neutral load will be on the unintended conductive path to your fire pump service bond.

 

[hhsting]

The ground current would just be local of the areas where the main bonds are, it takes more than just ground current to be a problem, if there is nothing in that area for ground current to cause a problem, there is no problem.

When you put them on opposite sides of the building, current will be on every grounded surface in the building, so your more likely to have that added variable that makes ground current a problem, like ground current on a gas line that has a break and the ground current arcs across it, or a water line and someone takes a shower and the current flows through from the shower head to the drain, or you have high neutral currents and few ground paths except say some flexible conduit that slightly rubs against a metal object in that path and it's a poor connection and when you have high neutral loading the poor connection sparks or someone gets in between the connection, or an electrician disconnects a #12egc and gets shocked. Or you lose your neutral from your service on your neutral loaded panel, your entire neutral load will be on the unintended conductive path to your fire pump service bond.

Please see sketch posts 60 and 44. I have never read what you are saying until now without no known cause. Posts 43 and 60 sketch cause problem?

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[Wire-Smith]

Unlikely to cause a problem, look for what possible conductive paths will connect the two bonds, if you don't see a likely problem there probably isn't. after install is complete, heavily load neutral and see what migrates to the fp panel.

And the most important part, post results here.
Lol, thanks

 

[electrofelon]

In my opinion and I've never heard an argument against this opinion. If disconnects are beside each other, the ground current will not cause any problems because there's nothing like gas lines, water lines, EGGs, etc. In between them for the current to cause a problem.


Another option that I gave earlier is a premises isolation xfmr on the system with neutral load before any neutral loads and only bond that secondary at one location.

Another possible option, you have to ask AHJ for special permission for is bonding at utility xfmr only and running EGGs with the service and installing surge arresstors at the premises( they would be called supply side bonding jumpers not EGC and sized as such ,but tomato potato)

I really thing you are overthinking this. Of course its a free country do whatever you want, but I think the OP should know that probably no one on this forum would do any of those things in the name of stopping objectionable currrent.

 

[hhsting]

I always thought rule of 230 grouping service disco was that fire fighter would know and easily shut off disconnect. After reading what was posted here, the rule of grouping service disconnect is their because if someone places service disco like oppsite to each other or not group causes ground current thru bldg?

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[Wire-Smith]

I really thing you are overthinking this. Of course its a free country do whatever you want, but I think the OP should know that probably no one on this forum would do any of those things in the name of stopping objectionable currrent.

I agree I am probably the equivalent of standing alone on mars on this topic.

 

[Wire-Smith]

I always thought rule of 230 grouping service disco was that fire fighter would know and easily shut off disconnect. After reading what was posted here, the rule of grouping service disconnect is their because if someone places service disco like oppsite to each other or not group causes ground current thru bldg?

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I doubt it, the code article I posted as the violation covers it

 

[hhsting]

Unlikely to cause a problem, look for what possible conductive paths will connect the two bonds, if you don't see a likely problem there probably isn't. after install is complete, heavily load neutral and see what migrates to the fp panel.

And the most important part, post results here.
Lol, thanks

Ok now see post sketch 29 and 60. Would that cause problem like you are saying?

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