If a main panel in a house is feed by a three wire service and meets all the code requirements for the main disconnect, does all the neutrals and the grounds need to be separated? I looked at a house today that had that scenario. Main breaker, three wire service with the green ground screw bonding the neutral to the can. The grounds and neutrals were all on the same neutral bar and I am trying to find out if this is a code violation. I have been looking around in the code, but I can?t seem to find the ref.
nuetrals and grounds on the same nuetral bar
- Thread starter copper123
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stud696981
Senior Member
Re: nuetrals and grounds on the same nuetral bar
As long as it's the main panel (first disconnect) then all can be on the same bar. If you have a disconnect box elsewhere or it's a subpanel, then it's all separate with a 4 wire install.
As long as it's the main panel (first disconnect) then all can be on the same bar. If you have a disconnect box elsewhere or it's a subpanel, then it's all separate with a 4 wire install.
pierre
Senior Member
- Location
- Westchester County, New York
Re: nuetrals and grounds on the same nuetral bar
Stud69 is correct, take a look at 250.20(B), 250.24,250.26 and 250.28
Stud69 is correct, take a look at 250.20(B), 250.24,250.26 and 250.28
bphgravity
Senior Member
- Location
- Florida
Re: nuetrals and grounds on the same nuetral bar
Also see Section 408.40. This section indicates that under certain conditions, a grounding terminal bar is required and grounding (bonding) conductors must be connected to it and not the bar provided for grounded (neutral) connections.
Also see Section 408.40. This section indicates that under certain conditions, a grounding terminal bar is required and grounding (bonding) conductors must be connected to it and not the bar provided for grounded (neutral) connections.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: nuetrals and grounds on the same nuetral bar
Copper123,
Let me take a stab at a verbal image. . .
In the service disconnect (what you call the "main disconnect") enclosure, the main bonding jumper (MBJ) (what you call the "green ground screw") ties together the equipment grounding conductors (EGC) (as you say, "grounds") and the branch circuit and feeder grounded conductors (as you say, "neutrals"). The terminal bar that the MBJ is connected to also is where the service entrance grounded conductor (SEGC) lands, as well as the grounding electrode conductor (GEC) that heads off to the grounding electrode system which will pick up the metal underground water pipe, ground rod, etc.
I'm guessing that you are asking about an installation where the branch circuit wiring method uses NM-B cable, thus there are EGCs and neutrals from the NM to terminate in this "service center".
I assume that the actual panel you are thinking of is listed as "suitable for use as service equipment". The specific manufacturer of that panel will have features that the terminal bar is capable of, such as, but not limited to, two EGCs under one screw, but the manufacturer, by making the panel "suitable for use as service equipment" says that the terminal bar, that the SEGC connects to, can also receive the GEC, MBJ, EGCs and neutrals.
Grouping all the NM EGCs on a separate terminal bar can certainly be done, and some will say how good that looks, but the separation of EGCs and neutrals in the service disconnect enclosure is electrically removed by the MBJ.
Copper123,
Let me take a stab at a verbal image. . .
In the service disconnect (what you call the "main disconnect") enclosure, the main bonding jumper (MBJ) (what you call the "green ground screw") ties together the equipment grounding conductors (EGC) (as you say, "grounds") and the branch circuit and feeder grounded conductors (as you say, "neutrals"). The terminal bar that the MBJ is connected to also is where the service entrance grounded conductor (SEGC) lands, as well as the grounding electrode conductor (GEC) that heads off to the grounding electrode system which will pick up the metal underground water pipe, ground rod, etc.
I'm guessing that you are asking about an installation where the branch circuit wiring method uses NM-B cable, thus there are EGCs and neutrals from the NM to terminate in this "service center".
I assume that the actual panel you are thinking of is listed as "suitable for use as service equipment". The specific manufacturer of that panel will have features that the terminal bar is capable of, such as, but not limited to, two EGCs under one screw, but the manufacturer, by making the panel "suitable for use as service equipment" says that the terminal bar, that the SEGC connects to, can also receive the GEC, MBJ, EGCs and neutrals.
Grouping all the NM EGCs on a separate terminal bar can certainly be done, and some will say how good that looks, but the separation of EGCs and neutrals in the service disconnect enclosure is electrically removed by the MBJ.
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