Allowability of Changing Panelboard circuits from 480 to 277 VAC

a0128958

Member
Location
Plano, TX, USA
We are replacing 180 quantity 1000W metal halide 480 VAC fixtures at a car dealership,

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on a one to one basis using 240W LED 277 VAC fixtures.

Each existing 480 VAC circuit for the existing lighting is two #10 wires plus a #10 ground, using 30 amp 2 pole breakers.

20151014_100230.jpg

The panel board has a 4-wire 480/277 VAC feed (i.e. with a neutral and a neutral bus). The panel board provides inside lighting circuits too, at 277 VAC using single pole breakers.

The existing ground wire is connected to the existing metal poles at the access hatch, and travels upward to a connection to the existing fixtures.

For the existing outside 480 VAC lighting circuits, the electrician is proposing to change the panelboard wiring in order to change these circuits' voltage to 277 VAC to accommodate the new fixtures. The proposal including appropriate labeling/marking of the wires at the panelboard end and at the pole/fixtures end.

No change is proposed to the actual (#10) wiring or actual (30 Amp 2-pole) circuit breakers.

Is this an NEC compliant change that we can be comfortable with?

Many thanks!

Best regards,

Bill
 

JFletcher

Senior Member
Location
Williamsburg, VA
I highly doubt 480 volt site poles have been supplied with a cable method.
Seen it. 277V walkway lights and 480V parking lot lights supplied by UF, at least from UG box to poles. Didnt think this was allowed unless the conductors were re-identified to indicate the higher voltage.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Seen it. 277V walkway lights and 480V parking lot lights supplied by UF, at least from UG box to poles. Didnt think this was allowed unless the conductors were re-identified to indicate the higher voltage.
since when is there a color code required by the code for voltage levels?

use the existing wires to pull new ones.
 

JFletcher

Senior Member
Location
Williamsburg, VA
since when is there a color code required by the code for voltage levels?

use the existing wires to pull new ones.
Dunno, thought 480V was orange/brown/yellow or something like that. Dont work with it enough to know.

as far as using existing direct-buried UF to pull in new UF, you must have some Jedi powers to do that. maybe a 10' length thru peat moss, but 80' thru red clay?
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Dunno, thought 480V was orange/brown/yellow or something like that. Dont work with it enough to know.

as far as using existing direct-buried UF to pull in new UF, you must have some Jedi powers to do that. maybe a 10' length thru peat moss, but 80' thru red clay?
The NEC does not specify a color code, just that the voltage system be marked according to a site standard. Color is only one way doing this.
 

Fulthrotl

~~Please excuse the mess. Sig under construction~~
Each existing 480 VAC circuit for the existing lighting is two #10 wires plus a #10 ground, using 30 amp 2 pole breakers.

View attachment 14231

The panel board has a 4-wire 480/277 VAC feed (i.e. with a neutral and a neutral bus). The panel board provides inside lighting circuits too, at 277 VAC using single pole breakers.
l
why not just get 480 volt led lights, and change them out, and be done with it?
most led drivers are 120~277, but you can order 480. then you don't have to
redo anything, and you can change the lights out with minimal difficulty.
 

iwire

Moderator
Staff member
Location
Massachusetts
Seen it. 277V walkway lights and 480V parking lot lights supplied by UF, at least from UG box to poles. Didnt think this was allowed unless the conductors were re-identified to indicate the higher voltage.
At some point someone has done everything.


I stick by my statement, I highly doubt that is the OPs situation.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Dunno, thought 480V was orange/brown/yellow or something like that. Dont work with it enough to know.

as far as using existing direct-buried UF to pull in new UF, you must have some Jedi powers to do that. maybe a 10' length thru peat moss, but 80' thru red clay?
Maybe not through red clay, but way back when I was an apprentice we pulled out some aluminum THW that was directly buried across a high school football field. It was replaced with one size smaller copper. We dug up the existing conductors at each side line, served the new conductors to the old ones at one side line, and connected the other end to a the winch line of a large wrecker. Worked great and as far as I know the conductors we pulled in some 40 years ago are still in use.
 

jap

Senior Member
At some point someone has done everything.


I stick by my statement, I highly doubt that is the OPs situation.
I highly doubt it also.
What I picture in my mind, is a whole lot of #10 Brown, Orange, Yellow and Green, (No White or Gray at all ), more than likely all solid, and more than likely will not budge in the pipe going to the Pole Lights.

I dont know what the OP meant by the electrician re-working the panels but may be meaning changing the 2p breakers to 1p.
Not sure what he'll do about the color for the Neutral but this type of changeover always leads to a hodge podge of very interesting conclusions if you know what I mean.:)


JAP>
 

jap

Senior Member
why not just get 480 volt led lights, and change them out, and be done with it?
most led drivers are 120~277, but you can order 480. then you don't have to
redo anything, and you can change the lights out with minimal difficulty.
Although this would be the greatest idea, it's hardly ever the avenue taken.

JAP>
 

jap

Senior Member
Instead of requiring us to provide a neutral at a switchbox for future Occ Sensors, maybe they should require us to provide a neutral to the Pole Lights with all of this new LED Retro stuff that's going on. That to me would be more useful.

JAP>
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Instead of requiring us to provide a neutral at a switchbox for future Occ Sensors, maybe they should require us to provide a neutral to the Pole Lights with all of this new LED Retro stuff that's going on. That to me would be more useful.

JAP>
you are free to do so for future installs.

btw - it has occurred to me that one could add a small single phase 480-277V xfmr for each circuit and not ground the secondary as it would not be required, so no need to change the wire colors. no idea cost wise how this works out.
 

jap

Senior Member
you are free to do so for future installs.

btw - it has occurred to me that one could add a small single phase 480-277V xfmr for each circuit and not ground the secondary as it would not be required, so no need to change the wire colors. no idea cost wise how this works out.
And you'd be free to do so, but, who would want to go and do something like that?


JAP>
 
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