I'm installing a new service in a house & I'm putting a disconnecting means on the outside under the meter. My first question is: Do I treat this disconnect enclosure as the service panel in regards to grounding & bonding? Do I bond the neutral block to the enclosure? Do I drive a ground rod & connect in this enclosure? Do I have to bond it to a water pipe? I know that is a lot of "first question", but here I go with some more. Since a separate ground bar isn't required at this point, can I run from the disconnect to the panel with 2 wire SE cable w/ bare neutral or do I need a 3 wire w/ ground cable? Thanks for any information.
Service Grounding & Bonding
- Thread starter dave683
- Start date
- Status
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Service Grounding & Bonding
At the outside service disconnect a main bonding jumper is installed. The grounding electrode conductor terminates here (typically). At the downstream panel, the grounded conductor is not bonded to the enclosure, IE a seperate neutral bar is installed.
The grounding electrode system is per the NEC section 250.50, if the water pipe qualifes as a grounding electrode you bond to it, if not the connection to the water pipe is done per 250.104, with the only difference being the location of the ground/bond to the water pipe.
At the outside service disconnect a main bonding jumper is installed. The grounding electrode conductor terminates here (typically). At the downstream panel, the grounded conductor is not bonded to the enclosure, IE a seperate neutral bar is installed.
The grounding electrode system is per the NEC section 250.50, if the water pipe qualifes as a grounding electrode you bond to it, if not the connection to the water pipe is done per 250.104, with the only difference being the location of the ground/bond to the water pipe.
jtb
Senior Member
- Location
- Pennsylvania
Re: Service Grounding & Bonding
Quick answers, others will supply code refs from 250..
Outside disconecting means is considered the service panel.
Grounded conductor (neutral) and grounding conductors are tied here, grounding electrodes(rods) are tied here also. If you have access to the water pipe, it is tied here also.
If you have access to the water pipe only from the inside panel, it is bonded to the ground bar & enclosure. You may need a second grounding source outside to the service disconnect, see Tom's answer.
From the outside service disconnect, you need to run your ungrounded conductors (hots), grounded conductor (neutral) and a grounding conductor. The neutral will land on an Isolated Neutral bar which is isolated from the ground and enclosure. The ground conductor lands on a ground bar that is bonded to the enclosure.
Quick answers, others will supply code refs from 250..
Outside disconecting means is considered the service panel.
Grounded conductor (neutral) and grounding conductors are tied here, grounding electrodes(rods) are tied here also. If you have access to the water pipe, it is tied here also.
If you have access to the water pipe only from the inside panel, it is bonded to the ground bar & enclosure. You may need a second grounding source outside to the service disconnect, see Tom's answer.
From the outside service disconnect, you need to run your ungrounded conductors (hots), grounded conductor (neutral) and a grounding conductor. The neutral will land on an Isolated Neutral bar which is isolated from the ground and enclosure. The ground conductor lands on a ground bar that is bonded to the enclosure.
Re: Service Grounding & Bonding
If I were doing the job I would drive my grounding electrode from this I would ground my service panel as well as the service disconnecting means I am not familar of your area as to tell you whether or not to ground your meter socket.I would bond the service disconnecting means as well as the panel.I cannot find any reason why you could not run your SE cable from your disconnect to your panel....as to bonding the water pipes I have never bonded the water pipes and never caught hell by any inspectors
If I were doing the job I would drive my grounding electrode from this I would ground my service panel as well as the service disconnecting means I am not familar of your area as to tell you whether or not to ground your meter socket.I would bond the service disconnecting means as well as the panel.I cannot find any reason why you could not run your SE cable from your disconnect to your panel....as to bonding the water pipes I have never bonded the water pipes and never caught hell by any inspectors
- Location
- Illinois
- Occupation
- retired electrician
Re: Service Grounding & Bonding
varnerelt,
Don
varnerelt,
A grounded to grounding bond at the panel would be a violation of 250.24(A)(5). A four wire cable is required from the outside service disconnect to the panel.
Don
karl riley
Senior Member
Re: Service Grounding & Bonding
One more question. Don, maybe you can tell me this. I was asked to look at a rural installation before the inspector comes out. The meter and main disconnect are on a post about 75 feet from the nearest building. It supplies two buildings. SE cable was used into the main building (two hots, one N, no G). The panel in the building has both neutral and grounding busses, with the bonding screw is turned in on the neutral bus. A bare GEC from the neutral bus goes out of the panel thru a concrete wall.
I am assuming that the feed should have been 4-wire and that neutral should be kept insulated from the can, with the GEC originating from the grounding bus. My question is, is there a distance limit for the service entrance post outside of a building?
Karl
One more question. Don, maybe you can tell me this. I was asked to look at a rural installation before the inspector comes out. The meter and main disconnect are on a post about 75 feet from the nearest building. It supplies two buildings. SE cable was used into the main building (two hots, one N, no G). The panel in the building has both neutral and grounding busses, with the bonding screw is turned in on the neutral bus. A bare GEC from the neutral bus goes out of the panel thru a concrete wall.
I am assuming that the feed should have been 4-wire and that neutral should be kept insulated from the can, with the GEC originating from the grounding bus. My question is, is there a distance limit for the service entrance post outside of a building?
Karl
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Service Grounding & Bonding
Karl, there is a difference between the 2002 and 1999 NEC on this issue. A three wire feed to the downstream panel is ok if there are no parallel paths for current flow. Most electricans now use a 4 wire feed and separate the neutral and ground. In Washington State, this is now required by a state code. There is no distance limit from the service to the building (there was a proposal in the 2002 cycle that was rejected, and I belive it is also proposed in the 2005 cycle).
Karl, there is a difference between the 2002 and 1999 NEC on this issue. A three wire feed to the downstream panel is ok if there are no parallel paths for current flow. Most electricans now use a 4 wire feed and separate the neutral and ground. In Washington State, this is now required by a state code. There is no distance limit from the service to the building (there was a proposal in the 2002 cycle that was rejected, and I belive it is also proposed in the 2005 cycle).
- Location
- Illinois
- Occupation
- retired electrician
Re: Service Grounding & Bonding
Karl,
Your case is not the same as the first post in this thread. In the first post there is only one building or structure involved and all panels after the service disconnect require a "4 wire" connection. In your case, the pole is a building or structure and it is unlikely that there are additional conductive paths between the pole and the buildings. The code will permit you to use a "3 wire" connection and rebond in this case. See 250.32(B)(2). I see that this is a rural installation. If there are livestock involved, you need to look at Article 547.
Don
Karl,
Your case is not the same as the first post in this thread. In the first post there is only one building or structure involved and all panels after the service disconnect require a "4 wire" connection. In your case, the pole is a building or structure and it is unlikely that there are additional conductive paths between the pole and the buildings. The code will permit you to use a "3 wire" connection and rebond in this case. See 250.32(B)(2). I see that this is a rural installation. If there are livestock involved, you need to look at Article 547.
Don
karl riley
Senior Member
Re: Service Grounding & Bonding
Good info, Tom and Don. No other metallic paths, so he's OK for inspection. Thanks.
Karl
Good info, Tom and Don. No other metallic paths, so he's OK for inspection. Thanks.
Karl
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