240v single phase secondary.

[kwired]

Let me start over and let's go back to this quote and overlook everything else. Output 'A' is grounded in my case. I understand the need for grounding. That being said. The wire for output 'A' and output 'B' are black colored wires and a voltage of 240v.


As per Article 100 definition of a grounded conductor. The wire for output 'A' is grounded via the terminal on the XFMR. Making it a grounded conductor.


As per Article 200.6. The wire for output 'A' should NOT be black in color. Being a grounded conductor.
200.6 Means of Identifying Grounded Conductors.

(A) Sizes 6 AWG or Smaller. An insulated grounded conductor
of 6 AWG or smaller shall be identified by one of
the following means:

(1) A continuous white outer finish.

(2) A continuous gray outer finish.

(3) Three continuous white stripes along the conductor?s
entire length on other than green insulation.

(4) Wires that have their outer covering finished to show a
white or gray color but have colored tracer threads in
the braid identifying the source of manufacture shall be
considered as meeting the provisions of this section.

(5) The grounded conductor of a mineral-insulated, metalsheathed
cable shall be identified at the time of installation
by distinctive marking at its terminations.

(6) A single-conductor, sunlight-resistant, outdoor-rated
cable used as a grounded conductor in photovoltaic
power systems, as permitted by 690.31, shall be identified
at the time of installation by distinctive white
marking at all terminations.

(7) Fixture wire shall comply with the requirements for
grounded conductor identification as specified in 402.8.

(8) For aerial cable, the identification shall be as above, or
by means of a ridge located on the exterior of the cable
so as to identify it.

My concern is that if i change to a white conductor it will be mistaken as a 120v circuit later down the road.
Sorry for all the confusion and i hope this is simplifying my concern.

You are correct, and it is still a grounded conductor and still should be white or gray. If you are concerned about misunderstanding down the road, maybe some signs or labels to somehow indicate this system does not have 120 volts would be a good idea.

If this system is limited to a particular piece of equipment maybe not as essential, but if this system is a premises wiring system and there is also another premises wiring system you must have ways of identifying each system anyway. See 210.5 and 215.12.

 

[mbrooke]

Bypassing all of the posts, the grounded phase should be white or gray.

I highly recomend that the transformer be center tap grounded...

 

[Smart $]

Bypassing all of the posts, the grounded phase should be white or gray.

Already covered.

I highly recomend that the transformer be center tap grounded...

And if it don't have a center tap???

(BTW, this was already covered, too)

 

[fmtjfw]

Bypassing all of the posts, the grounded phase should be white or gray.

I highly recomend that the transformer be center tap grounded...

Why do you assume the secondary has a center tap?
If it does why do you want it grounded?

If the current scheme has a single conductor grounded and the voltage to ground of 240V on the hot conductor, and a single pole OCPD (or a simple fuse), how is it safer with the center tap? With a grounded center tap you now need a 2-pole OCPD or two fuses.

Note: if you have a 120/240V scheme with fuses and a single 240v load, then when a single fuse blows the device is "off" but at 120V above ground.

Note: if you have a 240v scheme with one conductor grounded and a single fuse in the hot conductor when the fuse blows the device is off and at 0V above ground.