Equipment grounding conductors and neutral conductors terminating on neutral bar.

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DisconnectingMeans

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Pop Quiz:

You come across a panel with both the neutral and grounding conductors terminated on the neutral bus bar. The grounding conductors are all bonded to each junction box in the existing piping system that supplies all utilization equipment and outlets. The panel itself has a jury-rigged bond to the building steel but its straight to the panel can, with no connection to the neutral bus... How bad is this?
 
DisconnectingMeans said:
Pop Quiz:

You come across a panel with both the neutral and grounding conductors terminated on the neutral bus bar. The grounding conductors are all bonded to each junction box in the existing piping system that supplies all utilization equipment and outlets. The panel itself has a jury-rigged bond to the building steel but its straight to the panel can, with no connection to the neutral bus... How bad is this?
Click to expand...

For starters, if this is not the service main disconnect panel, this is not good because this panelboard must be 4-wire fed with a neutral grounded terminal bar isolated from case and grounding terminal bars. .
 
Does the neutral bar have a main bonding jumper installed?

How is this panel fed? 4 or 3 wire?

And is it a service disconnect?

I was trying to find the specific code, but wasn't able to, that talks about the GEC connection to the panel not relying on the can for a connection to the neutral bar - if this were a panel that had the main service disconnect that is!
If it's not the service disconnect you can't bond building steel to a sub-panel.
 
Say the panel isn't directly bonded to the neutral bar and its unknown wether or not it's bonded at the service disconnect... If you were to actually work in said panel(add a circuit of some kind) would you install a grounding bar and transfer every equipment grounding conductor from the neutral bar to the grounding bar? And if the system is properly bonded at the service disconnect, remove the jury-rigged building steel bond and bonding jumper from neutral bar to the grounding bar if it's there(unsure wether it is)?
 
sw_ross said:
Does the neutral bar have a main bonding jumper installed?

How is this panel fed? 4 or 3 wire?

And is it a service disconnect?

I was trying to find the specific code, but wasn't able to, that talks about the GEC connection to the panel not relying on the can for a connection to the neutral bar - if this were a panel that had the main service disconnect that is! not the service disconnect you can't bond building steel to a sub-panel.
Click to expand...

In a 3-wire service disconnect panelboard, the neutral main bonding jumper can be integral with the enclosure mounting pan and pan rail.
On the 3-wire main service disconnect, the green bonding screw bonds the terminal bar to the case and where a strap is provided, then it will bond the terminal bar to the case. The equipment grounding conductors (EGC) bond onto the common terminal bar(s).

If it's a 4-wire panelboard (fed from the service disco), then the neutral bar is mounted in an isolator to prevent any neutral connection to the case. The equipment grounding terminal bar is bonded to the equipment case and structural steel for the EGC bonding.
 
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DisconnectingMeans said:
Say the panel isn't directly bonded to the neutral bar and its unknown wether or not it's bonded at the service disconnect... If you were to actually work in said panel(add a circuit of some kind) would you install a grounding bar and transfer every equipment grounding conductor from the neutral bar to the grounding bar? And if the system is properly bonded at the service disconnect, remove the jury-rigged building steel bond and bonding jumper from neutral bar to the grounding bar if it's there(unsure wether it is)?
Click to expand...
Yes if the service disconnect is bonded all bonding downstream should be eliminated unless it meets the exceptions in 250.142(B). Incorrect neutral bonding is dangerous and it allows neutral current on all conductive paths to source. If you are wondering about the neutral bond you should disband this wonderment by proving it, don?t assume or guess.
The building steel on this sub panel should terminate on the EGC ground bar and the service disconnect should have a grounding electrode conductor to an electrode per 250.24 and 250.50
 
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