Single Phase in a Three Phase Panel

[Eric_P]

Long time reader, first time poster.
I have come across an existing instalation where I have a 3-phase panelboard being fed from a single conductor, tapped from the generator side of the ATS. The single phase conductor daisy-chains across all three bus bars. The panel is a MLO and is protected by a 1-pole 30A breaker. It feeds emergency only egress lighting.
Is this a code violation or just unorthodox? Chapter and Verse?
Thank you all.

 

[augie47]

The only violation might be in the fact that the line lugs might not be rated for multiple conductors.
As far as feeding the panel with 1 circuit it is unorthodox but does occur on occasion especially with computer equipment where there is a desire for multiple circuits but limited total load.

 

[Jim W in Tampa]

Wasted high dollar panel

 

[eprice]

Make sure there are no multi-wire branch circuits fed from this panel. All of the ungrounded conductors are on the same phase and may overload a shared neutral.

 

[ty]

The only violation might be in the fact that the line lugs might not be rated for multiple conductors.
As far as feeding the panel with 1 circuit it is unorthodox but does occur on occasion especially with computer equipment where there is a desire for multiple circuits but limited total load.

I took this photo from another recent thread.
Do you see any violation in using these Polaris taps in this manner to jump the Line Side Lugs that are rated for one conductor for the application mentioned in this thread?

 

[Eric_P]

So you've established for me that you think this is not against code. Is there anything in the code that says this is acceptable? My concern is that the panel is not being used for its intended use (i.e. three phase vs. single phase) and that is in the code under Sec. 110.
The reason I ask is that the EC on the project has halted work and requesting a $X change order to fix the "problem." I'm not sure I can find one.

 

[techntrek]

I'm thinking that the grounded conductor bar wouldn't be able to handle the load since normally only one phase is at peak voltage or current at a given moment. Only an issue if the total load is more than 1/3 of the panel's rating?

Probably also an issue with a split phase (or 3 phase) panel being fed with unsynced phases, since at times 2 or 3 of the phases will sync momentarily.

So this leads to a related question - any problem with harmonics or an overloaded GC if you supply a panel with unsynced sources? Assuming no double/triple-pole breakers or MWBCs?

 

[crazyboy]

I doubt that's in the manufacturers instructions.

 

[Eric_P]

The panel only feeds 1P20A breakers for lighting and I think a fire alarm panel. Not sure harmonics come into play here. There appears to be a dedicated and oversized neutral on each branch circuit as well. I don't have all of the specifics.
I think I've come to the conclusion that while the installation is certainly unorthodox, it?s perfectly within code and safe. We're only adding 6 more branch lighting circuits with minimal load. Thank you.

 

[augie47]

So you've established for me that you think this is not against code. Is there anything in the code that says this is acceptable? .

For the most part, the NEC is a "permissive" Code. If it does not prohibit something, it is acceptable

My concern is that the panel is not being used for its intended use (i.e. three phase vs. single phase) and that is in the code under Sec. 110.
.

You could contact the manufacturer to confirm, but my thought is the voltage rating is "maximum" permitted. I would not confuse it's "normal" use with it's intended use. All the suitable panels I see are marker 208/120, I have never seen one listed for 120v only.
In the same manner, you could use a 480/277 board on a 208 v system.

The reason I ask is that the EC on the project has halted work and requesting a $X change order to fix the "problem." I'm not sure I can find one.

I would have him or the appropriate inspector give you the NEC Code violation