do i need a seperate ground bus in the main panel

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bjzelectric

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i cant remember but i thought i heard that a main panel doesnt need a seperate ground bus, the neutral bus can accomodate the grounds and neutrals. is this ok or do i have to get a seperate ground bus for the grounds and bond the 2 bus bars together? by the way what exactly is the long green screw included with my new panel?
 
Welcome to the zoo! :smile:

bjzelectric said:
i cant remember but i thought i heard that a main panel doesnt need a seperate ground bus, the neutral bus can accomodate the grounds and neutrals. is this ok or do i have to get a seperate ground bus for the grounds and bond the 2 bus bars together? by the way what exactly is the long green screw included with my new panel?
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Neutrals and EGC's can use the same bus in the enclosure that contains the main disconnect. Beyond that, they must remain separate.

The screw is for bonding the enclosure (and thus, the non-insulated EGC bus) to the neutral in the above-mentioned main-disco enclosure.

The screw does not come installed because the manufacturer doesn't know whether this enclosure will house your main disco.
 
bjzelectric said:
i cant remember but i thought i heard that a main panel doesnt need a seperate ground bus, the neutral bus can accomodate the grounds and neutrals. is this ok or do i have to get a seperate ground bus for the grounds and bond the 2 bus bars together? by the way what exactly is the long green screw included with my new panel?
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Bonding of the neutral and ground bus bar (if so equipped) occurs at the main panel only. If your main panel has only a neutral bus that is isolated from the metal cabinet by plastic "feet", then the green screw provided has a place on the neutral bus just for it to be screwed through the bus and into a pre-drilled hole in the cabinet. This bonds the neutral bus to the metal enclosure. that same bus may then be used for the GEC/EGCs as well.

Watch for the limitations of the number and size of ground wires that may share one bus terminal. Read the information on the main panel sticker. Each neutral must have its own termination (not sharing a spot with another conductor). Typically 2-3 ground wires may share a bus terminal, but again, read your panel's information.

Some like to organize neutrals and grounds on their own respective buses. If you need to add a ground bus, you may, and be sure the neutral is bonded to the metal enclosure using whatever means provided by the mfr.
 
And, if you do add an equipment grounding bar, do not land neutrals there ,.. if you do the metal of the can will become part of the circuit. Equipment grounding conductors only, on the added ground bar .
 
the "green screw" causes me to ask a clarifing question. When you say "main" panel, are we correct to assume this panel serves as your service disconnecting means and there is no overcurrent device ahead of it ?
 
bjzelectric said:
i cant remember but i thought i heard that a main panel doesnt need a seperate ground bus, the neutral bus can accomodate the grounds and neutrals. is this ok or do i have to get a seperate ground bus for the grounds and bond the 2 bus bars together? by the way what exactly is the long green screw included with my new panel?
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The long green screw, by the way is the single most important part of the electrical system.
Look for the definition of the main bonding jumper in Art 100.

I am a little concerned about this question and your profile as an industrial electrician. Its a very basic question that any electrican who has installed a service knows.
 
tom baker said:
. . . I am a little concerned about this question and your profile as an industrial electrician. Its a very basic question that any electrician who has installed a service knows.
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Tom, I was concerned about that also. Consider that most industrial electricians work past the main service equipment and use metallic raceways. That is why it is difficult for a RW to work in an industrial setting and vise-versa. :)
 
I do not find it at all surprising that an industrial electrician would not be familiar with the green screw shipped with load centers. :smile:

Would we expect an electrician that has always wired homes to be familiar with PLCs and VFDs? :smile:
 
Tom, I was concerned about that also. Consider that most industrial electricians work past the main service equipment and use metallic raceways. That is why it is difficult for a RW to work in an industrial setting and vise-versa. :)
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. . . I am a little concerned about this question and your profile as an industrial electrician. Its a very basic question that any electrician who has installed a service knows.
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Well lets stay with the perfect storm here, EMT to a disconnect, no concentric/ eccentric knockout used, Two hot’s and a EGC. Choose your voltage of 208v or 240V. No bonding bushings required, one is under 250V to Ground, green screw should be put in, to bond.

I can see where the green screw question is a truly viable one.
 
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cadpoint said:
Well lets stay with the perfect storm here, EMT to a disconnect, no concentric/ eccentric knockout used, Two hot?s and a EGC. Choose your voltage of 208v or 240V. No bonding bushings required, one is under 250V to Ground, green screw should be put in, to bond.

I can see where the green screw question is a truly viable one.
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I don't really understand your post, but the green screw is only installed at the main service disconnect or the first means of disconnect for a SDS....no where else are you permitted to install the green main bonding jumper screw.
 
tom baker said:
The long green screw, by the way is the single most important part of the electrical system.
Look for the definition of the main bonding jumper in Art 100.

I am a little concerned about this question and your profile as an industrial electrician. Its a very basic question that any electrican who has installed a service knows.
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I wouldn't be surprised if a guy who was an industrial electrician had never installed a service.
 
Yes we should be careful how we address new people. How else are they going to be able to learn. Im glad I was 'thick skinned' to stick around all this time. Ive learned alot.

Especially with code questions. Calculations, and electronics. I still have trouble with some electronics because I dont work with it enough.
 
cadpoint, I forgot about that situation. The OP did mention the neutral so I went that direction, but, it is not uncommon to find the bar used as a grounding bar when no neutral is present and the screw is installed to bond the enclosure. I see it fairly often on small panels installed for HVAC equipment (208-240 load-no neutral) or in your "perfect storm" to provide a ground bar for a conduit grounded enclosure.
 
M. D. said:
And, if you do add an equipment grounding bar, do not land neutrals there ,.. if you do the metal of the can will become part of the circuit. Equipment grounding conductors only, on the added ground bar .
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I have seen mayn residential installations where the neutral / ground bar at the incoming service does not contain enough terminals / landings so another ground bar was added (typically) at the bottom of the panel and connected to the factory installed neutral / ground bar via insulated conductor. The additional bar contained neutral and ground connection are you indicating this is incorrect?
 
Mike01 said:
I have seen mayn residential installations where the neutral / ground bar at the incoming service does not contain enough terminals / landings so another ground bar was added (typically) at the bottom of the panel and connected to the factory installed neutral / ground bar via insulated conductor. The additional bar contained neutral and ground connection are you indicating this is incorrect?
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Check out 200.2(B) edit to add: 250.6(A) as well.

Even if the ground bar is connected with an insulated conductor, I would consider landing neutrals there a violation, unless the bar is insulated from the panel box.
 
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??

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But at the service entrance the box is grounded via the ?Green screw? so if you isolate the bar and connect it via insulated conductor it is still indirectly connect to the enclosure?
 
Mike01 said:
But at the service entrance the box is grounded via the ?Green screw? so if you isolate the bar and connect it via insulated conductor it is still indirectly connect to the enclosure?
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Yes, but not by a current carrying conductor.
 
additional neutrals

additional neutrals

So then what would be The proper way for adding neutral terminals into a ?service? panelboard with insufficient neutral terminals? Excuse my ignorance, but I have seen it done this way (as stated above) and assumed it was correct. Wow you learn something new every day I love this site.:D
 
Mike01 said:
So then what would be The proper way for adding neutral terminals into a ?service? panelboard with insufficient neutral terminals? Excuse my ignorance, but I have seen it done this way (as stated above) and assumed it was correct. Wow you learn something new every day I love this site.:D
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You get the optionial additional neutral bar from the panel manufacturer and install it per the provided instructions.

Note: At the main service disconnect there is no requirement that the neutral strip be isolated from the enclosure. There is a rule that prohibits using the enclosure as the grounded conductor, so any additional neutral strips must be connected to the main neutral by a bus connection or a wire.
 
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