Two GE Powermark MBJ screws

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chuckd83

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I'm working with a GE/ABB Powermark panel with two neutral/ground buses. The buses do not have a bonding strap installed from the factory.

The panel came with two green screws, one preinstalled on the right bus. The left bus has a hole for the second screw which came in a bag.

I will land my GEC on the right bus, the service grounded conductor on the left bus, and bond the two buses together via #6 cable. The main service disconnect is inside this panel.

I'm hesitant to use the second screw on the left side bus.

If a load neutral conductor is landed on the right bus, load current could travel into the right screw, through the enclosure, and out the left screw to the service.

Or is this how it's supposed to be installed and I don't need the #6 bonding jumper?
 
chuckd83 said:
I'm working with a GE/ABB Powermark panel with two neutral/ground buses. The buses do not have a bonding strap installed from the factory.

The panel came with two green screws, one preinstalled on the right bus. The left bus has a hole for the second screw which came in a bag.

I will land my GEC on the right bus, the service grounded conductor on the left bus, and bond the two buses together via #6 cable. The main service disconnect is inside this panel.

I'm hesitant to use the second screw on the left side bus.

If a load neutral conductor is landed on the right bus, load current could travel into the right screw, through the enclosure, and out the left screw to the service.

Or is this how it's supposed to be installed and I don't need the #6 bonding jumper?
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It seems to me that the screw is adequate, at least so UL thinks, if this is an appropriate wire to wire it.

I don't know what a "service grounded conductor" is. Can you please elaborate on what you mean by this phrase?
 
petersonra said:
It seems to me that the screw is adequate, at least so UL thinks, if this is an appropriate wire to wire it.

I don't know what a "service grounded conductor" is. Can you please elaborate on what you mean by this phrase?
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The service conductor other than the ungrounded ones where current returns. The neutral conductor from the service. I'm not sure the technical name for it.

It just seems wrong for normal load current to travel through the enclosure. I can understand for fault current, but not everyday load current.
 
chuckd83 said:
The service conductor other than the ungrounded ones where current returns. The neutral conductor from the service. I'm not sure the technical name for it.

It just seems wrong for normal load current to travel through the enclosure. I can understand for fault current, but not everyday load current.
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Is this what you have? If so you will need to bring the structure grounding electrode system GEC to the same bus.
 
Probably GE’s reason behind it, if it is not service equipment, then one is the neutral bar without the screw, and the other is used as a ground bar with the screw, if service equipment, both use the screws. Siemens, if I remember correctly has an optional non-metallic piece that replaces the metal buss at the bottom, to convert one bar to grounds only.
 
hillbilly1 said:
Probably GE’s reason behind it, if it is not service equipment, then one is the neutral bar without the screw, and the other is used as a ground bar with the screw, if service equipment, both use the screws. Siemens, if I remember correctly has an optional non-metallic piece that replaces the metal buss at the bottom, to convert one bar to grounds only.
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Yes, that's what I figured. This is service equipment so both screws are used and the two buses are bonded via the enclosure.

My problem is landing branch circuit neutrals on the right bus. As load current would go through the enclosure. I feel like I should only put the neutrals on the left bus.

Or I could only use the right screw and bond the two buses together via cable. Then load current wouldn't go through the enclosure, but rather the cable.
 
chuckd83 said:
Yes, that's what I figured. This is service equipment so both screws are used and the two buses are bonded via the enclosure.

My problem is landing branch circuit neutrals on the right bus. As load current would go through the enclosure. I feel like I should only put the neutrals on the left bus.
Click to expand...
It is GE………LOL!
 
chuckd83 said:
Yes, that's what I figured. This is service equipment so both screws are used and the two buses are bonded via the enclosure.

My problem is landing branch circuit neutrals on the right bus. As load current would go through the enclosure. I feel like I should only put the neutrals on the left bus.
Click to expand...
If you need more neutral circuits, you would need to run a bond wire over to the second bus, but it would need to be whatever size the neutral has to be, not necessarily #6.
 
chuckd83 said:
The service conductor other than the ungrounded ones where current returns. The neutral conductor from the service. I'm not sure the technical name for it.

It just seems wrong for normal load current to travel through the enclosure. I can understand for fault current, but not everyday load current.
Click to expand...
The panel is not permitted to be the only path for the neutral current. See 200.2(B). If you have a bonding jumper between the two bars, that would be the main path for the neutral current, and the code does not prohibit parallel paths for neutral current in the service equipment.

Do you have the complete part number or a link to the instructions for the panel?
 
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