I have an existing residence where I will be installing a new 200A enclosed main breaker between the service meter load side conductors and the existing 200A main panel. Here's how I understand it... The supplied screw that bonds the Neutral lug assembly to the enclosure is the "main bonding jumper" and the GEC's (relocated from existing main panel) and EGC's (including the EGC from the SER now feeding the main panel) are landed in the factory supplied ground lugs in the new enclosure. As I write this, I think I've convinced myself, but will still throw it out there for confirmation.
Gounding/Bonding of 200A Enclosed Main Breaker
- Thread starter csoc64
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jumper
Senior Member
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- 3 Hr 2 Min from Winged Horses
Yep. Sounds good. You did separate EGCs and neutrals in old main panel? Neutral not bonded to old panel can?
Affirmative.
kwired
Electron manager
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- NE Nebraska
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- EC
Don't forget to remove the bonding jumper from the existing panel, otherwise you effectively create a parallel path serving both EGC and neutral conductors, and really make the whole idea of separating them pointless as well.
meternerd
Senior Member
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- Athol, ID
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- retired water & electric utility electrician, meter/relay tech
Just be sure the factory ground lugs are where you need them. At the service disconnect, if the GEC is terminated on a separate ground bus or a lug screwed to the can, rather than the neutral bus, there must be a wire or busbar jumper between the neutral and ground bus. You are not allowed to depend on the service disconnect enclosure to be the only connection between ground and neutral. I have shot down many where the GEC was terminated to a lug that was screwed to the can and the neutral was bonded to the can with a green screw. Not acceptable. Don't have the Code reference, though. Sorry.
jumper
Senior Member
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- 3 Hr 2 Min from Winged Horses
250.24(A)(1)
jxofaltrds
Inspector Mike®
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- Mike P. Columbus Ohio
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Did you change the 'feeder'? H-H-N-G
You didn't say.
You didn't say.
Just to clarify, the GEC's must connect to the grounded conductor (for grounded systems). You cannot connect them to anything on the can side of the bonding screw. See 250.24(A)(1).
Where the main bonding jumper is wire or busbar, you can connect GEC's to the EGC terminal, bar, or bus. See 250.24(A)(4).
jumper
Senior Member
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- 3 Hr 2 Min from Winged Horses
OP said the old main panel was fed with SER.
jxofaltrds
Inspector Mike®
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- Mike P. Columbus Ohio
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- ESI, PI, RBO
:slaphead::slaphead::slaphead:
kwired
Electron manager
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- NE Nebraska
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- EC
I think there is more to it then just 250.24(A)(1). That section does tell us where we are permitted to connect the GEC.
200.2(B) says: The continuity of a grounded conductor shall not depend on a connection to a metallic enclosure, raceway, or cable armor.
This means the grounded conductor (neutral) can not rely on the enclosure or a raceway or cable sheath to carry current of the grounded conductor. It doesn't mention the GEC, but the fact 250.24(A)(1) doesn't mention the enclosure limits the use of the enclosure for the GEC, but not necessarily for other neutral to ground bonding situations
250.102(A) says: Bonding jumpers shall be of copper or other corrosion-resistant material. A bonding jumper shall be a wire, bus, screw, or similar suitable conductor.
In application of this one we commonly depend on the incoming neutral conductor then a screw that bonds the can at service equipment and from there metal raceways serving as EGC's for downstream circuits.
meternerd
Senior Member
- Location
- Athol, ID
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- retired water & electric utility electrician, meter/relay tech
Yup...I was only referring to the GEC. My preference was to see the GEC terminated on the neutral bus (if available), rather than on a separate ground bus. The main bonding jumper was usually installed correctly. I think the lug provided that was screwed to the can was an invitation to connect the GEC there with no jumper to the neutral bus. Most of the problems were from one manufacturer of multi meter apartment panels. Nice big ground lug just waiting for the GEC and no separate ground bus.
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