EGC on neutral bar.

[reyamkram]

When I was working in a 480 volt 3 phase panel, no neutral just straight 480 volt 3 phase, I found, some EGC connected to the neutral bar, this is a sub panel,
no connection from the neutral bar to the panel, and the neutral bar was connected to a ground rod, I did remove the EGC and install them on the ground bar that
is connected to frame of the panel. what type of electrical hazard could that be, if there was a ground fault. we do have the pipe for a ground fault path, if the pipe did not come loss, or is not tight at the connection points. This is and old industrial building and that is very possible. What are some thoughts on this matter.


Thank you, for any and all information.

 

[electrofelon]

When I was working in a 480 volt 3 phase panel, no neutral just straight 480 volt 3 phase, I found, some EGC connected to the neutral bar, this is a sub panel,
no connection from the neutral bar to the panel, and the neutral bar was connected to a ground rod, I did remove the EGC and install them on the ground bar that
is connected to frame of the panel. what type of electrical hazard could that be, if there was a ground fault. we do have the pipe for a ground fault path, if the pipe did not come loss, or is not tight at the connection points. This is and old industrial building and that is very possible. What are some thoughts on this matter.


Thank you, for any and all information.

Sounds fine to me if the raceway is an approved egc. See 250.118.

 

[winnie]

If the 'neutral bar' was not actually connected in some hidden way to the building EGC system, but was connected to a ground rod, then you have a serious safety concern.

A ground rod often doesn't have a low enough impedance to clear a fault. At 480V a fault to a 25 ohm ground rod would draw 11A (presuming this is actually a 480/277 wye system), cooking a bunch of worms and creating a dangerous step potential in the soil, raising the voltage of all connected EGC wires, but not opening the breaker. And 25 ohms for a ground rod is just a random number; the rod resistance to the other grounding electrodes could be much higher or lower.

Now if the connection to the ground rod also means a connection to the building grounding electrodes and thus a connection to the service neutral, then you would have a solid ground fault path and the breakers would trip.

Connection to soil is never an acceptable ground fault path for low voltage.

-Jon

 

[kwired]

When I was working in a 480 volt 3 phase panel, no neutral just straight 480 volt 3 phase, I found, some EGC connected to the neutral bar, this is a sub panel,
no connection from the neutral bar to the panel, and the neutral bar was connected to a ground rod, I did remove the EGC and install them on the ground bar that
is connected to frame of the panel. what type of electrical hazard could that be, if there was a ground fault. we do have the pipe for a ground fault path, if the pipe did not come loss, or is not tight at the connection points. This is and old industrial building and that is very possible. What are some thoughts on this matter.


Thank you, for any and all information.

Sounds to me like you improved it. Presuming they used metallic wiring methods, those are allowed to be utilized as the EGC. There may be issues with concentric/eccentric ko's and or loose fittings, but still a better chance of decent enough fault return path vs a ground rod only. If you have a lot of building steel or metallic pipelines or such (depends on construction and kind of activity goes on in your plant possibly) you may be covered by those regardless even though NEC doesn't recognize them as EGC's.

 

[winnie]

and the neutral bar was connected to a ground rod, I did remove the EGC and install them on the ground bar that
is connected to frame of the panel.

Forgot a question in my previous post:

When you moved the EGC to the ground bar, did you also move the connection to the ground rod? All of these should be landed on the ground bar, not the neutral bar of a subpanel.

-Jon

 

[kwired]

Forgot a question in my previous post:

When you moved the EGC to the ground bar, did you also move the connection to the ground rod? All of these should be landed on the ground bar, not the neutral bar of a subpanel.

-Jon

I understood he had an isolated bar, no supply neutral, an EGC from one or more circuits and the ground rod were all that was connected. Of course if this were EGC conductors plus metallic wiring methods, chances are it all ties together eventually anyhow, but still an improper approach on how to do it.

 

[reyamkram]

If the 'neutral bar' was not actually connected in some hidden way to the building EGC system, but was connected to a ground rod, then you have a serious safety concern.

A ground rod often doesn't have a low enough impedance to clear a fault. At 480V a fault to a 25 ohm ground rod would draw 11A (presuming this is actually a 480/277 wye system), cooking a bunch of worms and creating a dangerous step potential in the soil, raising the voltage of all connected EGC wires, but not opening the breaker. And 25 ohms for a ground rod is just a random number; the rod resistance to the other grounding electrodes could be much higher or lower.

Forgot a question in my previous post:

When you moved the EGC to the ground bar, did you also move the connection to the ground rod? All of these should be landed on the ground bar, not the neutral bar of a subpanel.

-Jon

Yes, I removed the connection from ground rod that went to the natural bar, and did not reconnect to the ground bar to ground rod.
The panel is feed from a 200 amp breaker in switch gear, the panel is 480 volt 3 phase 3 wire, no natural or a wire type EGC, only the conduit as
the EGC, all of the ground and bounding should of been done at the switch gear, from what I understand.

Thank you.

 

[kwired]

Yes, I removed the connection from ground rod that went to the natural bar, and did not reconnect to the ground bar to ground rod.
The panel is feed from a 200 amp breaker in switch gear, the panel is 480 volt 3 phase 3 wire, no natural or a wire type EGC, only the conduit as
the EGC, all of the ground and bounding should of been done at the switch gear, from what I understand.

Thank you.

In that situation I have installed the neutral/ground bonding strap/screw/etc. and landed all my EGC's on that neutral assembly. I don't see any code issues with it as long as no circuits needing a neutral conductor are never installed.

Nothing prohibits connecting a grounding electrode here there is just no requirement to do so. Any electrode connected here can not be a substitute for the one required at the service or first disconnect at a feeder supplied building either though.

 

[reyamkram]

In that situation I have installed the neutral/ground bonding strap/screw/etc. and landed all my EGC's on that neutral assembly. I don't see any code issues with it as long as no circuits needing a neutral conductor are never installed.

Nothing prohibits connecting a grounding electrode here there is just no requirement to do so. Any electrode connected here can not be a substitute for the one required at the service or first disconnect at a feeder supplied building either though.

Thank you for the information.

 

[reyamkram]

Forgot a question in my previous post:

When you moved the EGC to the ground bar, did you also move the connection to the ground rod? All of these should be landed on the ground bar, not the neutral bar of a subpanel.

-Jon

Thank you, yes I removed the connection to the ground rod, the ground bar is connected to the frame of the sub panel, I should have a good EGC
with the conduit going back to the 480/277 volt switch gear.