Identification of ungrounded conductors

[pipe_bender]

Article 220 explains the systems


(A) Voltages. Unless other voltages are specified, for purposes
of calculating branch-circuit and feeder loads, nominal
system voltages of 120, 120/240, 208Y/120, 240, 347,
480Y/277, 480, 600Y/347, and 600 volts shall be used.

120/240 is one system as far as the NEC is concerned not to mention the physics of one center tapped winding.

the way I read it if there are one or more three phase systems and a split phase system in the same building one can use the same color for each leg of the split phase system.

 

[don_resqcapt19]

So in a commercial application... 120/ 208, still nominal as the 120 v is just a leg as said above. If your using all black/ white MC cable 12 awg... We don't usually mark this as its smaller than the minimum size to be marked. Is this correct.

Yes, if the 208Y/120 volt system is the only voltage system in the building all of the ungrounded conductors are permitted to be black.
The rule should probably require phase or line identification for all systems that would permit the use of multiwire circuits, but it doesn't.

 

[jaggedben]

If a dwelling has a PV system with say energy storage is that DC a second nominal voltage or are PV systems exempt?.

One could say no because PV and ESS DC circuits aren't branch circuits.

 

[Jpflex]

The main reason i brough up identification of ungrounded conductors is because i have seen hazards arrise from the same color wires being supplied from different poles or terminated on a 2 pole breaker.

i have seen hazards arrise from such same colored conductors with opposing potential being combined at wire nuts within junction boxes.

Does NEC not address this?