Service Panel - Bonded Grounds and Neutrals or Not?

[hardworker]

My whole life I have always combined the Neutral bar and the Ground bar bonded together on a Main Service Panel. Always isolated the Ground bar and isolated the Neutral bar on Sub-panels.

A young electrician is now telling me it makes no difference on the Main Service Panel if the Ground bar and Neutral bar are bonded together or isolated. He does agree on a Sub-panel the Ground bar and Neutral bar must be isolated.

What are the current facts and rules on this topic?

 

[letgomywago]

He's wrong. Only one place in a system can they share a bar or else the metal parts bonded to anything electrical will be able carry current and pose a hazard.

 

[LarryFine]

What are the current facts and rules on this topic?

If the EGCs are not bonded to the neutral, they can not perform their main function: to assure that a fault from a line to an exposed conductive housing or enclosure makes the OCPD behave like it would for a line to neutral fault before someone receives a shock.

 

[infinity]

A young electrician is now telling me it makes no difference on the Main Service Panel if the Ground bar and Neutral bar are bonded together or isolated. He does agree on a Sub-panel the Ground bar and Neutral bar must be isolated.

What does this mean? Is he saying that the EGC's and neutrals can be on separate bus bars? They can but they're ultimately connected through the MBJ.

Hardworker, please update your profile with your current location and occupation data. Thank you.

 

[hardworker]

Where do I update my profile?

 

[Strathead]

What does this mean? Is he saying that the EGC's and neutrals can be on separate bus bars? They can but they're ultimately connected through the MBJ.

Hardworker, please update your profile with your current location and occupation data. Thank you.

To add to Infinity, 250.102 is the reference and table 250.102 is the size.

 

[electrofelon]

What does this mean? Is he saying that the EGC's and neutrals can be on separate bus bars? They can but they're ultimately connected through the MBJ.

The code language seems to say exactly that: that the egc's and neutrals go on separate bars but are connected via the MBJ.

 

[roger]

Where do I update my profile?

Click on your name and in the small window that opens click on the settings on the right and then edit

 

[RASanders]

I would ask him to consider where, other than the Neutral and Ground bus bars in the Main Service Panel, he would otherwise install the absolutely essential Main Bonding Jumper that is required to provide the at-one-point bonding of the Grounding Electrode Conductor system to the Neutral (service grounded conductor) bus bar?

Is there another location he has in mind that would perform the same function?

Is it not that one bonding point that provides the connection and fault-current carrying function of all fault-current carrying Equipment Bonding Conductors, which are landed on all sub-panel isolated 'ground' bars, and which are all in turn bonded back to the Main Service Panel ground bar, to carry the fault current of a short, to return to the source breaker and cause it to trip?

What's his alternative plan to ensure the entire electrical system of that building functions for selective coordination of over-current protection devices so that a fault in the installation is cleared by the protection device located immediately upstream of the fault?

 

[infinity]

I would ask him to consider where, other than the Neutral and Ground bus bars in the Main Service Panel, he would otherwise install the absolutely essential Main Bonding Jumper that is required to provide the at-one-point bonding of the Grounding Electrode Conductor system to the Neutral (service grounded conductor) bus bar?

Does the MBJ actually make this connection or is the GEC connected directly to the neutral? With the green screw type of MBJ the MBJ does not connect the GEC to the neutral.

 

[kwired]

My whole life I have always combined the Neutral bar and the Ground bar bonded together on a Main Service Panel. Always isolated the Ground bar and isolated the Neutral bar on Sub-panels.

A young electrician is now telling me it makes no difference on the Main Service Panel if the Ground bar and Neutral bar are bonded together or isolated. He does agree on a Sub-panel the Ground bar and Neutral bar must be isolated.

What are the current facts and rules on this topic?

They can't be isolated. They do not need a wire jumper or bus bar between them at the service IF they are bonded through the metal enclosure.

Grounded conductors (neutrals) however can not depend on the enclosure to complete the circuit path