Re-identification of conductors in a cable assembly

[Nutmegger]

Residential job. The customer had his own 12/3 AC cable and wanted us to use it to wire his addition. Not sure if he's saving any money, but I don't get involved in bidding.
The boss said "yes". There are no MWBC's, and there are just two three-way switch setups, but every lighting outlet and receptacle will still be fed with a 12/3 cable, thus wasting an extra conductor in most of the circuits.

So, seeing as one of the hot conductors is getting wasted, and the steel jacket of the AC is not the best grounding conductor, I was thinking of re-designating the red as the extra grounding conductor, a la HCF MC, by marking it with green tape inside the boxes. Before my boss laughs at me, can you guys tell me if this is allowed -- re-designating ungrounded conductors as grounING ones?

And a follow-up question... Say we had 12/4 on hand (white, red, black and blue). Could we use it as 12/2/2, i.e. could we re-designate the blue as another neutral?

I know you can re-designate a grounded conductor in a cable assembly as a "hot", but want to know if a "hot" can be re-marked as a grounding or a grounded...

 

[augie47]

You can re-identify, but keep 404.2(C) in mind. You may need that extra conductor.

 

[texie]

Residential job. The customer had his own 12/3 AC cable and wanted us to use it to wire his addition. Not sure if he's saving any money, but I don't get involved in bidding.
The boss said "yes". There are no MWBC's, and there are just two three-way switch setups, but every lighting outlet and receptacle will still be fed with a 12/3 cable, thus wasting an extra conductor in most of the circuits.

So, seeing as one of the hot conductors is getting wasted, and the steel jacket of the AC is not the best grounding conductor, I was thinking of re-designating the red as the extra grounding conductor, a la HCF MC, by marking it with green tape inside the boxes. Before my boss laughs at me, can you guys tell me if this is allowed -- re-designating ungrounded conductors as grounING ones?

And a follow-up question... Say we had 12/4 on hand (white, red, black and blue). Could we use it as 12/2/2, i.e. could we re-designate the blue as another neutral?

I know you can re-designate a grounded conductor in a cable assembly as a "hot", but want to know if a "hot" can be re-marked as a grounding or a grounded...

Take a look at 200.6 and 250.119 for both questions.

 

[ActionDave]

....So, seeing as one of the hot conductors is getting wasted, and the steel jacket of the AC is not the best grounding conductor,....

In anything other than old, old AC cable the steel jacket is an excellent equipment ground. Leave the spare conductor and just cap it off.

 

[Nutmegger]

Thanks guys.. point duly taken about capping off the extra conductor; Thank you for pointing me to the proper place in NEC as well. Also, valid point about bringing the neutral to the switch boxes.

Here's a follow-up question..
Exceptions about reidentifying both the neutral and the EGC read along the lines that "Where the conditions of maintenance
and supervision ensure that only qualified persons service the installation, [grounded or EGC] conductors in multiconductor cables shall be permitted to be permanently identified at their terminations at the time of installation."

I realize that this is probably the AHJ's call, but in your guys opinion or experience, does "Where the conditions of maintenance
and supervision ensure that only qualified persons service the installation" usually mean "not in a residential setting"?