250.32 (A), doubt.

[don_resqcapt19]

Yes. The primary purpose of the grounding electrode (ground rod) and connections is to dissipate over voltages from lightning, and static electricity, etc. For lightning overvoltages, a short path is best because impedance factors become a dominant issue with lightning. You want those to bleed to ground in as short a run as a possible (i.e., at the structure grounding electrode).

You are also correct that once you establish the second ground, you've established a parallel path via the ground. I believe our NEC is written the way it is because the danger at the structure (due to overvoltages from lightning) is considered more dangerous than the parallel path created by the two ground points. We accept the relatively small problem with the parallel ground path to solve the bigger problem of lightning.

The parallel path for the grounded conductor does occur with a service as the utility connects it to a grounding electrode at their end, and it is connected a second time at the service equipment. The original question here involved feeder conductors and not service conductors to the houses. Where the building or structure is severed by a feeder, the grounding electrode is not connected to the grounded conductor at the building disconnect. It is only connected to the equipment grounding conductor, and does not create a parallel path for neutral current.

 

[Adamjamma]

Hi,

All that you say Is not about our country, first, se are located in Central America, the meter and the main disconnect service, both, are in the limit of the property due to the accesibility of the utility company to read the consume kwh of the client, however in some areas this measurament is remote.
All relative to the instalation, specification and design is according to the NEC from USA, and the IEEE standards, mainly because our system works with a 60Hz Frecuency, San Jose capital of Costa Rica, was the third city lighted in the world, so we have standards for Power system pretty defined.
And i never have seen people from Jamaica or other island coutry working as electrician here.
My doubt with the 250.32(A), was related the definition of separated buildings and its approch, but it has been clarify by don now.

Thanks for your interest and the info of the diferent codes in the caribbean.

Regards,

I was mentioning the style of install is the same as the Caribbean, which makes sense as it followed Central and South America, and even now shows preference in imports from those areas rather than from the USA. Mainly due to politics.
It is interesting that Costa Rica had power so early. But again, not surprising...
Have fun.

 

[Adamjamma]

The parallel path for the grounded conductor does occur with a service as the utility connects it to a grounding electrode at their end, and it is connected a second time at the service equipment. The original question here involved feeder conductors and not service conductors to the houses. Where the building or structure is severed by a feeder, the grounding electrode is not connected to the grounded conductor at the building disconnect. It is only connected to the equipment grounding conductor, and does not create a parallel path for neutral current.

Could that be why I am required a number 4 wire in its own conduit from the meter/disconnect grounding electrode to the house electrode? This can be run in the same trough before filling with concrete but may bot run in same conduit... Jamaican code..lol

Simply to keep the ground electrodes tied? from the property fence line to the house. What is funny is, if I put in a fence with foundation of masonry at the property line, it cannot connect to this ground system near the meter, and if I run lights to it, the found for the lights must be run in their own conduits from the house, even if low voltage.
Been trying to understand why the rules in the codes.. especially as put in codes in 90s...

 

[INGMRS]

The parallel path for the grounded conductor does occur with a service as the utility connects it to a grounding electrode at their end, and it is connected a second time at the service equipment. The original question here involved feeder conductors and not service conductors to the houses. Where the building or structure is severed by a feeder, the grounding electrode is not connected to the grounded conductor at the building disconnect. It is only connected to the equipment grounding conductor, and does not create a parallel path for neutral current.

Hi Don,


It is correct, should not be a bonding between the neutral bar and the grounding bar in the load side. 250.32 (D)(1)


But Don, i have seen several images including, from the books of mike holt and illustrated handbook, that include a disconnect means located in Separate Building, but i not clear if this is necessary, because the disconnect means at the service is protecting to this feeder.


I don't remember this main disconnect at the separate building is a requirment, normally in CR you arrive with your to hot wires directly to the terminals of the panelboard, the grounded conductor to the neutral bar, and grounding conductor directly to the grounding bar.


Regards,

 

[Adamjamma]

the reason why you tie directly to the three spots with your wires is you usually are using lug panels and the main disconnect is back at the meter.. so you are using a four wire feed from right under the meter. Which is like we feed to a secondary panel in the USA but just as we do the feed in Jamaica.

So, your Ground wire and your Neutral wire are run separate from the main disconnect, and in the same conduit, or on the same overhead line...

Then it is optional to either connect directly to your panel lugs for the breakers with your live wires or, the way I do it usually, run into a breaker there as a main breaker.
The advantage of placing a main breaker in the panel is the ability to stop the incoming power in the panel, without having to go to the meter area to turn the power to the panel off. But, the wires to the main breaker in the panel are still live, which is why I buy the lugs to mains adapter to move the main breaker to above the breaker assembly... plus I hate to lose the two spots on the breaker panel...
However, this adds to the cost of the install and is not necessary as one can always go to the meter area and turn off the main breaker there, then go to the panel and do what they need to do.. and then no live wires are in the panel at all while working.

But, there is nothing wrong with the way you do your installs, and the difference between the way the USA and Costa Rica handle the first panel Neutral and Ground wire are based on where the two countries put the Main Breaker-Disconnect. Since your Disconnect is below the meter at the property line, all the main ground connections are usually there as well, and so it is four wire from there to the main panel.

You can ignore the main disconnect pictures at the main panel as this in your case would be a secondary disconnect and is thus optional. I prefer it myself, but not all customers can be convinced to spend the extra money for it, as they know they have to spend the money for the breaker-disconnect at the meter.

 

[Dennis Alwon]

In your diagram, the placement of the electrode is correct for the actual service. In many case 2 rods are needed. What everyone is saying is that at each building there would be a feeder-- assuming there is no overcurrent protective device at the meter. You would need 4 conductors - 2 hots, neutral and an equipment grounding conductor, you would also need to drive 1 or 2 rods at each building and bond it to the equipment grounding conductor, not to the neutral. The neutral at each building should not be bonded to the can. Each building would also need whether a main breaker or following the 6 disconnect rule- no more than six handles to disconnect the building.

 

[GoldDigger]

...
...
But Don, i have seen several images including, from the books of mike holt and illustrated handbook, that include a disconnect means located in Separate Building, but i not clear if this is necessary, because the disconnect means at the service is protecting to this feeder.
...
....

You are mixing two reasons for required devices.
1. The wire (unless it is service conductors or a code compliant tap) needs to be protected by OCPD, either fuse(s) or breaker(s). You are correct that the fused disconnect or breaker at the service could be protecting the feeder, and there is no protective requirement, for example, for a main breaker at a downstream panel.
2. Each service and each supplied separate building needs a local disconnect at that building. This is not necessarily (except in the case of a service) a fused disconnect or disconnect otherwise associated with OCPD. All you need is a means of positively turning off all electrical power to the building that does not require you to go to another building to find the disconnect.

 

[don_resqcapt19]

...
But Don, i have seen several images including, from the books of mike holt and illustrated handbook, that include a disconnect means located in Separate Building, but i not clear if this is necessary, because the disconnect means at the service is protecting to this feeder. ... Regards,

The second building is required to have a disconnect, it is not required to have an overcurrent protective device. It is a requirement so that there is a quick and easy local method to disconnect the separate building from its power source. See 225.31 and the following sections for the separate building disconnect requirements.

 

[INGMRS]

The second building is required to have a disconnect, it is not required to have an overcurrent protective device. It is a requirement so that there is a quick and easy local method to disconnect the separate building from its power source. See 225.31 and the following sections for the separate building disconnect requirements.

Hi don,


I do not know, I do not have so clear the idea of installing a second disconnection device for the same feeder, I have read the sections, but basically if you have access to your disconnection device, everything is fine, of course, I understand that it is recommended to have it near the building. but. How many feet (meters)?

Regards,

 

[don_resqcapt19]

Hi don,


I do not know, I do not have so clear the idea of installing a second disconnection device for the same feeder, I have read the sections, but basically if you have access to your disconnection device, everything is fine, of course, I understand that it is recommended to have it near the building. but. How many feet (meters)?

Regards,

The code language says inside or outside the building nearest the point of entrance of the conductors into the building. Based on that language, if the disconnect is outside the building, I require it be be installed on the outside surface of the building. Some inspection authorities permit a few feet away from the building wall.

 

[Adamjamma]

Hi don,


I do not know, I do not have so clear the idea of installing a second disconnection device for the same feeder, I have read the sections, but basically if you have access to your disconnection device, everything is fine, of course, I understand that it is recommended to have it near the building. but. How many feet (meters)?

Regards,

you have the disconnection under the meter... thus, since feeding with four wires from the meter post to the residence, another disconnection outside the residence is not required. But, you should probably put a disconnect in the panel. However, not required, just safer.
Because your system is more like a trailer type of residential install it is hard to use many of the pictures to see what you need to do. Your standard practice is to both ground and main disconnect at the property line, then to feed from there with two live, a neutral, and a ground, to the panel inside the residence. This is so the utility can look for the meter easier.

Now, if you are required a firefighter disconnect on the exterior of the home, that would be another issue altogether. But just look at it as being closest to a sub panel or a Trailer/ Mobile Home connection.

 

[don_resqcapt19]

you have the disconnection under the meter... thus, since feeding with four wires from the meter post to the residence, another disconnection outside the residence is not required. But, you should probably put a disconnect in the panel. However, not required, just safer.
Because your system is more like a trailer type of residential install it is hard to use many of the pictures to see what you need to do. Your standard practice is to both ground and main disconnect at the property line, then to feed from there with two live, a neutral, and a ground, to the panel inside the residence. This is so the utility can look for the meter easier.

Now, if you are required a firefighter disconnect on the exterior of the home, that would be another issue altogether. But just look at it as being closest to a sub panel or a Trailer/ Mobile Home connection.

The NEC rules very clearly require a disconnect at the residence.

 

[Adamjamma]

The NEC requires a Main Disconnect and the grounding point to be there. The main disconnect is at the residence property line.

The main disconnect for mobile homes is not at the mobile home but at the meter disconnect usually. But best policy is to use a main disconnect in each panel, however this is not the service disconnect, but the panel disconnect.
There is a difference due to the install differences...

In most cases in the Caribbean at least, the difference in distance from the service disconnect below the meter to the first panel in the home is around 50 feet.

It is kind of like the regional differences in the USA with panels in basements, panels in hallways and panels on the outside of the buildings...
225.32 Location. The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements in 230.6 shall be utilized.


The Caribbean usually justifies this readily accessible location nearest the point of entrance to be the meter post under the meter, unless the locality requires a firefighters disconnect, in which case they normally install it under the following European directive:

537.4.2.2 Every firefighter's switch should comply with the following requirements, where applicable: (i) for an outdoor installation, the switch should be outside the building and adjacent to the equipment, or alternatively a notice indicating the position of the switch should be placed adjacent to the equipment and a notice should be fixed near the switch so as to render it clearly distinguishable (ii) for an indoor installation, the switch should be in the main entrance to the building or in another position to be agreed with the local fire authority (iii) the switch should be placed in a conspicuous position, reasonably accessible to firefighters, at not more than 2.75 m from the ground or the standing beneath the switch. 537.4.3 A firefighter's switch shall be easily visible, accessible and marked to indicate the installation or part of the installation which it controls.


Now, local codes change Island to Island and in other countries as well around the world as differences or amendments to the basic NEC codes, just as there are differences in the NYC and Chicago codes. Based upon what the local authorities deem more applicable to their own requirements, since the NEC plainly states it is not a design book but a guideline of best practices.

 

[INGMRS]

The NEC requires a Main Disconnect and the grounding point to be there. The main disconnect is at the residence property line.

The main disconnect for mobile homes is not at the mobile home but at the meter disconnect usually. But best policy is to use a main disconnect in each panel, however this is not the service disconnect, but the panel disconnect.
There is a difference due to the install differences...

In most cases in the Caribbean at least, the difference in distance from the service disconnect below the meter to the first panel in the home is around 50 feet.

It is kind of like the regional differences in the USA with panels in basements, panels in hallways and panels on the outside of the buildings...
225.32 Location. The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements in 230.6 shall be utilized.


The Caribbean usually justifies this readily accessible location nearest the point of entrance to be the meter post under the meter, unless the locality requires a firefighters disconnect, in which case they normally install it under the following European directive:

537.4.2.2 Every firefighter's switch should comply with the following requirements, where applicable: (i) for an outdoor installation, the switch should be outside the building and adjacent to the equipment, or alternatively a notice indicating the position of the switch should be placed adjacent to the equipment and a notice should be fixed near the switch so as to render it clearly distinguishable (ii) for an indoor installation, the switch should be in the main entrance to the building or in another position to be agreed with the local fire authority (iii) the switch should be placed in a conspicuous position, reasonably accessible to firefighters, at not more than 2.75 m from the ground or the standing beneath the switch. 537.4.3 A firefighter's switch shall be easily visible, accessible and marked to indicate the installation or part of the installation which it controls.


Now, local codes change Island to Island and in other countries as well around the world as differences or amendments to the basic NEC codes, just as there are differences in the NYC and Chicago codes. Based upon what the local authorities deem more applicable to their own requirements, since the NEC plainly states it is not a design book but a guideline of best practices.

Hello,


I agree with you that the code is not a design book, it is a guide to the best practices to have an installation as secure as possible. So, here is my question: if we do not use CR metal pipes for water or gas (because we use PVC), and 95% of the electrical installations are in PVC conduits, and the house does not have lightning protection, what is ? The purpose of this second rod? I mean, on the load side there is a grounding bar on the board, and this bar is connected by an EGC to the electrode in service, and this electrode is connected to the neutral point On the service side, therefore, there is already a direct route to the source to eliminate any ground fault. Why a second electrode?


As Mike Holt says in his videos, more "ground" is not necessary the best. in this case the most important is the fourth wire to connect both sides, the load with the source, (of course, this is my opinion).


Regards,