ECN Forum Forums General Topics of the Trade General Discussion Area Post light Feed

Maybe he wants that receptacle for 2000W of Christmas lights.

Dave

Would 210.6(A)2002 NEC, apply to this since it was said it was residental?

Bob,

From an Advance Spec Sheet: "IntelliVolt models shall operate from 50/60 Hz input source of 120V through 277V with sustained
variations of +/- 10% (voltage and frequency) with no damage to the ballast."

Also, even though the "neutral" terminal of these ballasts is often white, I couldn't find anything on the ballast spec sheets to say that they have to be wired L-G. I'm not saying you are wrong, but I want to know for sure one way or the other. I'll try contacting the manufacturer...



[This message has been edited by mhulbert (edited 04-08-2006).]

If you just do the lights you can meet 3% voltage drop with a 3 wire circuit as follows:
black hot #8 feeding lights 1,3,5,7,9
red hot #6 feeding lights 2,4
red hot #8 feeding 6,8,10 from light 4
white neutral #10
green same as red hot

The outlet is a real killer. A 15A outlet can be done by feeding 1/0 conductors (black and red) to a 240/120 2KVA transformer which feeds a GFI receptacle on the secondary. This would also require a 1/0 neutral and 1/0 grounding conductor, for a total of 4 1/0 wires.

If you run the 1/0 outlet circuit, the lighting circuit green conductor can be omitted and the 1/0 green can be used for both circuits.

The most rational would be to run 600V on 2 #12s or maybe 2 #10s with a step up transformer at the building and a step down at the outlet. The green could be the same as the phase wire. I'm not sure what size the white from the building would be required to be.

fixed last sentence to refer to white wire


[This message has been edited by jfwayer (edited 04-08-2006).]

If it gets freezing cold there in the winter, florescent lights won't work well.

I've always wondered just how useful using a pair of step-up/step-down transformers would be for long low voltage runs to prevent voltage drop.

While the increased voltage means lower current and thus less power lost in the wires, the transformers have impedance and will introduce their own voltage drop under load. Put two 5% impedance transformers in series, and you either have to oversize them considerably or you start out with 10% voltage drop under full load.

-Jon

A higher voltage drop may be more acceptable if the voltage drop is at least uniform. The catch is, the lights closer to the source will have a higher voltage than the lights at the far end of the run. It's a lot easier to see that the system has a problem if the lights are not equal in brightness.

I do not know if this kind of wiring meets code, but so far I've not run across anything in NEC that would prohibit it:

Run a 3-wire cable (white, black, red) along all the post lights. Run a 2-wire cable (white, black) from the house to the first post light. Connect like color wires at each junction, including the red wires in the 8 middle post lights. Wire each light to white and RED (not black). At the very last light connect red and black together.

This won't eliminate voltage drop. But what it will do is make it uniform and more tolerable. The hot side of the circuit runs down the black wire all the way to the end. Then it runs backwards along the red wire to each light. Each light is thus involving an equivalent length of wire and equivalent voltage drop. So you will get the same voltage at each light, however low that happens to be.

To calculate what the drop will be, figure it as if all lights are at the very end of the run.

You might then correct the voltage drop with a buck-boost transformer if you're sure of the exact wattage that will always be used. Or maybe just order some 100 volt bulbs from Japan

Hmmmmm.......


Article 100 defines a dwelling unitas:


Similarly, a one-family dwelling is defined as:


Since the outside drive is neither a building nor "one or more rooms," my interpretation would be that 210.6(A) doesn't apply.

What do the code experts think?

Even if 210.6(A) did prohibit the use of 240V lamps, presumably there would still be nothing to prevent the 480V feed with transformers idea, since the step-down xfmr at each post would drop the voltage back to 120V at the lamp terminals, which is what the rule refers to.


[This message has been edited by pauluk (edited 04-09-2006).]

mhulbert, I stand corrected, thanks for the info.

Bob

PDH


Assuming the cables are smaller than 1/0 IMO 310.4 prohibits what you suggest.

If you are going to run 3 wire go the way Jon (Winnie) suggested with the multiwire circuit which has the advantages of 240 volt distribution with the convenience of 120 volt fixtures.

Also keep in mind if you do use cables and you run larger cable for voltage drop you will not be able to comply with 250.122(F) which requires the increase in the EGC as Jon mentioned.


The breaker size will need to be a 15 or 20 unless you install heavy duty sockets or fuses at each pole.


I recommend staying with a 15 or 20 amp circuit regardless.

This is not going to be a cheap job if you decide to keep the voltage drop within the recommended 3% for branch circuits.

Bob

By the way, the compact florescent suggestion is IMO a good one that should be considered, you can drop the load by about 75% while maintaining the light levels.