Changing from 277V to 208V supply for road way pole lights.

[kwired]

Yeah at times we seem to have very high voltage readings, on some 277V readings I have had as high as 300V

So the line to line voltage on that same system is around 520?? If you derive a 120/240 system from that (with no changeable taps) you will get about 130/260.

These readings fairly constant or only when load is light?

 

[BullsnPyrs]

But Tom does have a good point, the 30 amp circuit is only allowed if the "lighting unit" has a "heavy-duty lampholder".

I think that is usually interpreted as "mogul", though it does not seem to be defined that way. Had to imagine that an LED module socket is "heavy-duty" though.

The LED module never sees line voltage, a driver is installed to convert line voltage to whatever the LED module requires to operate.

 

[wireguy8169]

So the line to line voltage on that same system is around 520?? If you derive a 120/240 system from that (with no changeable taps) you will get about 130/260.

These readings fairly constant or only when load is light?

kwired, this has been typically in a no load situation, though the line to line Voltage I have measured is typically close to the nominal voltage (470-490) its when I read line to neutral where we have it that it has run high. I realize this is just the average on the meter but when I get a 300+Volt reading on the 277 (no load typcially) it seems high. Sorry not trying to start a thread with in the thread and we have not have problems with equipment going bad though I have only been here a year now.

thanks for the input.

 

[wireguy8169]

Just to clarify there is not lamp holder on these LED heads it is a complete unit, remove the old head and retro fit the new. I have convinced my supervisor that the Voltage drop for this distance should be addressed just for warranty issues if nothing else so we are going to try and split the circuits into two if we have to go 208V or use a delta/wye 480/480 tranny and a mlo panel in the room where we only have the 480V 4 wire supply. I have contacted the manufacture also and they said the drive should fire the light with out an issue but we would just have to account for the current increase at the further heads,

thanks again for all the input.

 

[kwired]

kwired, this has been typically in a no load situation, though the line to line Voltage I have measured is typically close to the nominal voltage (470-490) its when I read line to neutral where we have it that it has run high. I realize this is just the average on the meter but when I get a 300+Volt reading on the 277 (no load typcially) it seems high. Sorry not trying to start a thread with in the thread and we have not have problems with equipment going bad though I have only been here a year now.

thanks for the input.

Is line to neutral voltage high on all three phases? Bad neutral someplace could be in play here, but if one phase is high at least one of the other two should be low, it all depends on how the load is balanced, that is if the line to line voltages are at a normal range.

 

[MadWulf]

Why not just upsize the wire from the building to the first pole. That will solve your voltage drop problems, and you will not have to replace the wiring between the poles as long as the breaker is properly sized.

Or did I miss something?

 

[Volta]

The LED module never sees line voltage, a driver is installed to convert line voltage to whatever the LED module requires to operate.

I agree. But I'm talking about current, not voltage. How would you comply with 210.23(B or C)? These are fixed lighting units. . .

 

[BullsnPyrs]

I agree. But I'm talking about current, not voltage. How would you comply with 210.23(B or C)? These are fixed lighting units. . .

I see these articles as prohibiting the use of fixed lighting units with lampholders that are not heavy duty in circuits of 30 to 50 amps in non-dwelling units and allows utilization equipment in any occupancy. Lighting fixtures that do not contain any form of a lampholder qualifies as utilization equipment under article 100.