I have a customer who bought 10 acres and built a barn/apartment. He built a 400-amp service with (2) 200amp disconnects. One disconnect feeds the barn/apartment and the other 200-amp is for the future home. He is now building his home and ran a 4/0 4-wire from the disconnect at the service to a panel in his new basement of the home. (Main Lug) All the water lines in the house are plastic including the one coming from the well. My question is what is the proper way to ground his home? Where should the ground rod be driven? What do I need to do about a water bond?
Grounding a house
- Thread starter jeff1166
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Re: Grounding a house
It is not possible to bond plastic piping, thus you don't need to do it. The grounding electrode should be installed as close to the power entrance location as possible - 250.30(4). You mentioned that the house panel is main lug only. You should be aware of 225.32 which says you need to have a disconnecting means at the building served. I read this to mean that panel should have a main breaker or you need to have a separate disconnect on that house. Code refs are 2002 NEC.
It is not possible to bond plastic piping, thus you don't need to do it. The grounding electrode should be installed as close to the power entrance location as possible - 250.30(4). You mentioned that the house panel is main lug only. You should be aware of 225.32 which says you need to have a disconnecting means at the building served. I read this to mean that panel should have a main breaker or you need to have a separate disconnect on that house. Code refs are 2002 NEC.
Re: Grounding a house
I would drive the rod as close to the feeder entrance as conveniently possible, so that plan sounds okay. You cannot bond plastic pipe so, no, you won't have a water bond. NEC 250.104(A) calls for the bonding of "Metal Water Piping". If you don't have METAL water pipes, there is no requirement to bond.
I would drive the rod as close to the feeder entrance as conveniently possible, so that plan sounds okay. You cannot bond plastic pipe so, no, you won't have a water bond. NEC 250.104(A) calls for the bonding of "Metal Water Piping". If you don't have METAL water pipes, there is no requirement to bond.
B
bthielen
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Re: Grounding a house
My home has plastic water line from the well and then it is copper within my home. When I rewired my home my inspector had me ground the copper water lines in the home that were conductive. The reason is that the water's impurities could provide a conductive path to the well, which is about 200' from the house and this could introduce voltage potential. This makes sense to me.
I would like to ask a question. If my water lines throughout my home were non-conductive, would it not be possible that the valves at my sink, shower, etc. could then potentially require grounding?
Bob
My home has plastic water line from the well and then it is copper within my home. When I rewired my home my inspector had me ground the copper water lines in the home that were conductive. The reason is that the water's impurities could provide a conductive path to the well, which is about 200' from the house and this could introduce voltage potential. This makes sense to me.
I would like to ask a question. If my water lines throughout my home were non-conductive, would it not be possible that the valves at my sink, shower, etc. could then potentially require grounding?
Bob
mikeames
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- Gaithersburg MD
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- Teacher - Master Electrician - 2017 NEC
Re: Grounding a house
Although this sounds good in theory and is true it is not a concern for the following reason.
Figure the amount of potential that point A in the well would be to point B in the house????? A few volts at max. Now figure the voltage drop that wiould occur between point "A" a few hundred feet mineral filled water and point "B" ???? The final voltage would be 0.
Even if salt water was pumped through the pipes it would drop the small voltage that might be present.
the differences in potential is real and very interesting, but not a concern in our field.
If it were a large enough potential,,,,WOW we found a new energy source
were rich..
Although this sounds good in theory and is true it is not a concern for the following reason.
Figure the amount of potential that point A in the well would be to point B in the house????? A few volts at max. Now figure the voltage drop that wiould occur between point "A" a few hundred feet mineral filled water and point "B" ???? The final voltage would be 0.
Even if salt water was pumped through the pipes it would drop the small voltage that might be present.
the differences in potential is real and very interesting, but not a concern in our field.
If it were a large enough potential,,,,WOW we found a new energy source
were rich..
B
bthielen
Guest
Re: Grounding a house
My understanding of one of the purposes for all the ground connections and bonding at service entrances, equipotential planes, steel buildings, etc. is to bond all these various ground connections to each other, equalizing potential differences. Am I out in left field?
Look forward to comments.
Bob
This then returns me to the question I posed to my inspector. Why was it necessary to bond my copper water lines inside my home when the only connection they have to earth is the liquid water. (aside from the code requirement) I guess I am questioning the reason behind the code.
My understanding of one of the purposes for all the ground connections and bonding at service entrances, equipotential planes, steel buildings, etc. is to bond all these various ground connections to each other, equalizing potential differences. Am I out in left field?
Look forward to comments.
Bob
- Location
- Illinois
- Occupation
- retired electrician
Re: Grounding a house
Bob,
The inside metal water lines are bonded to prevent them from becomming energized by some type of electrical fault. If a hot conductor would somehow cone into contact with unbonded water lines the lines would become energized and there would be line voltage between the lines and any "grounded" object. The bonding will prevent this from happening.
Don
Bob,
The inside metal water lines are bonded to prevent them from becomming energized by some type of electrical fault. If a hot conductor would somehow cone into contact with unbonded water lines the lines would become energized and there would be line voltage between the lines and any "grounded" object. The bonding will prevent this from happening.
Don
Re: Grounding a house
To expand on what Don said, if the metal water piping is bonded and an energized conductor comes in contact with it, the bonding conductor will provide a low impedance current path back to the service and enough current should flow to trip the breaker. If the piping is not bonded and an energized conductor comes in contact with it, it will just sit there energized for someone to touch.
jeff,
Another question, how far do the conductors run from the point where they enter the house to the point where they enter the panel in the basement? Will this be in compliance with the location requirement of 225.32?
To expand on what Don said, if the metal water piping is bonded and an energized conductor comes in contact with it, the bonding conductor will provide a low impedance current path back to the service and enough current should flow to trip the breaker. If the piping is not bonded and an energized conductor comes in contact with it, it will just sit there energized for someone to touch.
jeff,
Another question, how far do the conductors run from the point where they enter the house to the point where they enter the panel in the basement? Will this be in compliance with the location requirement of 225.32?
david
Senior Member
- Location
- Pennsylvania
Re: Grounding a house
1. I have a customer who bought 10 acres and built a barn/apartment.
2. He built a 400-amp service with (2) 200amp disconnects. One disconnect feeds the barn/apartment and the other 200-amp is for the future home.
Jeff:
Is this service separate from the Barn/apartment, In other words is this a ?central distribution??
Please read 547.9 If I understand you right you have feeders coming from a 400 amp service I believe you will have to run a full sized equipment grounding conductor. (The equipment-grounding conductor is the same size as the largest supply conductor, if of the same material, or is adjusted in size in accordance with the equivalent size columns of Table 250.122 if of different materials.)
Where is the well? Would the well casing be available as a grounding electrode?
1. I have a customer who bought 10 acres and built a barn/apartment.
2. He built a 400-amp service with (2) 200amp disconnects. One disconnect feeds the barn/apartment and the other 200-amp is for the future home.
Jeff:
Is this service separate from the Barn/apartment, In other words is this a ?central distribution??
Please read 547.9 If I understand you right you have feeders coming from a 400 amp service I believe you will have to run a full sized equipment grounding conductor. (The equipment-grounding conductor is the same size as the largest supply conductor, if of the same material, or is adjusted in size in accordance with the equivalent size columns of Table 250.122 if of different materials.)
Where is the well? Would the well casing be available as a grounding electrode?
Re: Grounding a house
David & Eprice, The barn/apartment is technically a garage. I do not think it would classify as agricultural. The service on the building is one 400-service and meter base with (2) 200-amp disconnects. One disconnect feeds the "garage and the other feeds the new house . The panel will be located in the basement about 10' of the entrance. If I am understanding everyone correctly it sounds like I should run a water bond anyway and attach it to the first copper section I can find, and install possibly (2) ground rods 6' apart from each other. I also need to keep the panel as close as possible to the entrance of the basement.
David & Eprice, The barn/apartment is technically a garage. I do not think it would classify as agricultural. The service on the building is one 400-service and meter base with (2) 200-amp disconnects. One disconnect feeds the "garage and the other feeds the new house
. The panel will be located in the basement about 10' of the entrance. If I am understanding everyone correctly it sounds like I should run a water bond anyway and attach it to the first copper section I can find, and install possibly (2) ground rods 6' apart from each other. I also need to keep the panel as close as possible to the entrance of the basement.karl riley
Senior Member
Re: Grounding a house
Travis, spacing the ground rods 6' apart has nothing to do with magnetic fields. It is so that you get the benefit of two rods, since if they are close together they act more like one rod. In other words, they need some space to conduct to earth.
Karl
Travis, spacing the ground rods 6' apart has nothing to do with magnetic fields. It is so that you get the benefit of two rods, since if they are close together they act more like one rod. In other words, they need some space to conduct to earth.
Karl
karl riley
Senior Member
Re: Grounding a house
If there is no metal water pipe feed in the ground, I would use two electrodes, in this case rods.
Karl
If there is no metal water pipe feed in the ground, I would use two electrodes, in this case rods.
Karl
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Grounding a house
bthielen
Your connection to the copper water lines is a Section 250.104 bonding connection. Use of the water pipe as a grounding electrode is not the same, nor done for bonding-low impedance path to facilitate the operation of the overcurrent protective device.
Use of the water pipe as a grounding electrode is covered in Secion 250.50 and 52. This connection is to limit overvoltage due to lighting. Since most new houses have plastic water pipes supplying the house, the connection to the metallic pipes is for 250.104 and can be done anywere in the structure, as long as the connection is accessbile.
bthielen
Your connection to the copper water lines is a Section 250.104 bonding connection. Use of the water pipe as a grounding electrode is not the same, nor done for bonding-low impedance path to facilitate the operation of the overcurrent protective device.
Use of the water pipe as a grounding electrode is covered in Secion 250.50 and 52. This connection is to limit overvoltage due to lighting. Since most new houses have plastic water pipes supplying the house, the connection to the metallic pipes is for 250.104 and can be done anywere in the structure, as long as the connection is accessbile.
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