3 phase 240V delta panelboard neutral required?

[davejwalker]

Hello All,
I have a situation where we are re-purposing an old 3 phase 240V delta service that supplied one piece of equipment - to now run several pieces of equipment.
The existing service consisted of 1 - 200A disconnect powering a single load.
We now will be powering 6 - 240V single phase air conditioning units.
The plan was to simply replace the existing disconnect with a panelboard, add the required 2 pole breakers and be done.
The inspector is telling us that if we do that - we would now have to pull a neutral to the panel.
I am not finding any code reference that requires a neutral to be present at the panel.
Can someone please point me to the code that would reference this?
Thanks!

 

[xformer]

Hello All,
I have a situation where we are re-purposing an old 3 phase 240V delta service that supplied one piece of equipment - to now run several pieces of equipment.
The existing service consisted of 1 - 200A disconnect powering a single load.
We now will be powering 6 - 240V single phase air conditioning units.
The plan was to simply replace the existing disconnect with a panelboard, add the required 2 pole breakers and be done.
The inspector is telling us that if we do that - we would now have to pull a neutral to the panel.
I am not finding any code reference that requires a neutral to be present at the panel.
Can someone please point me to the code that would reference this?
Thanks!

this is not a code requirement but more likely a load requirement. The Load may require the neutral conductor.

 

[Dsg319]

Only place you should have to bring it to if you have a grounded system (center tapped neutral) is to the service equipment for the neutral to EGC bond.

As long as you have straight 240volt loads.

 

[jap]

this is not a code requirement but more likely a load requirement. The Load may require the neutral conductor.

The OP indicated the panel would be feeding condensing units which do not require a neutral connection.


JAP>

 

[xformer]

The OP indicated the panel would be feeding condensing units which do not require a neutral connection.


JAP>

If it does not need one, then it doesn't need one.

 

[augie47]

Two key issues: (1) Is it the service panel (2) Is the service grounded at the source (POCO).
If the answer to both those is "yes" then 250.20(B) and 250.24(C) will require a neutral be brought to the service panel.

Note: If it remains an ungrounded system, the inspector may require detectors per 250.21(B)

 

[davejwalker]

Two key issues: (1) Is it the service panel (2) Is the service grounded at the source (POCO).
If the answer to both those is "yes" then 250.20(B) and 250.24(C) will require a neutral be brought to the service panel.

Note: If it remains an ungrounded system, the inspector may require detectors per 250.21(B)

This is a great point that I hadn't considered!
The new panel would be down stream from the service disconnect.
There is currently no neutral at the service disconnect and only ground rods tied to the GEC so there is no good fault path back to the source. (only earth resistance)
So the correct fix would be to provide a neutral from the service disconnect to the utility. and an EGC to the new panel.
Does this sound right to you all?

 

[Dsg319]

Is it possible it’s corner grounded or un-grounded?

Where does the GEC terminate in the service equipment?

 

[augie47]

You are correct in that there is no need to run a neutral anywhere beyond the service disconnect unless required by load.
As Dsg319 suggests, there are options where a neutral would not be installed to,the service (form POCO). Your 1st step should be to check with POCO and confirm the configuration of their supply (240/120, or 240 delta). In the event it's a 240 delta then you need to confirm if it is ungrounded or purposely corner grounded (1 phase connected to earth-ground)at your service.

 

[Dsg319]

If you are at the job site or have guys there, have someone measure from phase conductor to ground with a low impedance meter.

If it’s ungrounded you shouldn’t get anything from all three phases to ground.

If it’s corner grounded two of the phases will read 240volts from phase conductor to ground. And one phase will read 0volts to ground. (That will be your grounded conductor.) Wether that’s intentional from the POCO or a fault down the line.

I would still contact the POCO to verify there configuration as others have said.

 

[Tulsa Electrician]

You mentioned two pole breakers. Be sure to use the correct type.