Metal Halide light Question.

[sparky723]

I am installing 2 -1000w MH lights on a pole approx. 25-30 ft in the air. Each light will have its own pole. 2 lights, 2 poles.
The panel is about 425' away. It is a 120/240 panel and since I want to use as little $ as possible to run the fixtures, I am choosing a multi-tap fixture with 240v connection inside.
The question is this: With the panel being so far away, what is the best way to find the PROPER wire size. I believe it is #6.
Any help would be appreciated.
Thanks, Sparky

P.S.- I don't have amperage info. at this time.

 

[iwire]

I am installing 2 -1000w MH lights on a pole approx. 25-30 ft in the air. Each light will have its own pole. 2 lights, 2 poles.
The panel is about 425' away. It is a 120/240 panel and since I want to use as little $ as possible to run the fixtures, I am choosing a multi-tap fixture with 240v connection inside.

First thing is that no matter what the voltage is they are 1000 watt fixtures and each one will use just over 1 kWh per hour. This will not change if you run them on 12 volts or 600 volts.

However the higher voltage does allow the use of smaller condutors.

The question is this: With the panel being so far away, what is the best way to find the PROPER wire size.

With a voltage drop calculation, but you must have the circuit amperage.

So I went to the Graingers web site looked up a 1000 watt MH ballast and found it's ratings

9 amps @ 120 volt
5.2 amps @ 208 volt
4.5 amps @ 240 volt
3.9 amps @ 277 volt
2.5 amps @ 480 volt

So you have two 4.5 amp fixtures you want to run at 240 volts with a one way distance of 425'

I went to three different on-line voltage drop calculaters and here is what I come up with.

You can use 6 AWG copper and end up fine with just 1.6% voltage drop. But you do not have to use 6 AWG.

Looking into it more you could use 8 AWG copper for 2.5% voltage drop.

Calculated Results

Estimated Drop 5.8 Volts

At Circuit End 234.2 Volts

Voltage Drop 2.4 Percentage


If it was me, and I was sure no one would want to add load to this I would run 1" PVC with three 8 AWG THWN-2 copper in the PVC.

 

[sparky723]

Whats the advantage of hooking them up 240 instead of 120? Just being able to use smaller wire? I thought there was a savings when using a higher voltage. i.e.-277 lights over 120 lights (in same rooom)... Have I been mislead?
And I was gonna run 3 #8's and 1 #10 in an 1 1/4" PVC. Need a ground and neutral. (laymans terms..lol)
Thanks to Iwire for his help and to anyone else who can lend a thought. Have a great day!

 

[iwire]

Whats the advantage of hooking them up 240 instead of 120? Just being able to use smaller wire?

The advantage is the higher the voltage the lower the current. The lower the current the less voltage drop you will get.

The higher the voltage the less voltage drop matters.

I thought there was a savings when using a higher voltage. i.e.-277 lights over 120 lights (in same rooom)... Have I been mislead?

A common misconception but all other things being equal watts are watts and the power company charges by the watt.

And I was gonna run 3 #8's and 1 #10 in an 1 1/4" PVC. Need a ground and neutral. (laymans terms..lol)
Thanks to Iwire for his help and to anyone else who can lend a thought. Have a great day!

1.25" is great for such a long run. You will be able to vacuum a pull string in the 450' no problem.

If you run these lights at 240 volt you will not need a neutral.

You would need two hots and the equipment grounding conductor.

Forget the 10 AWG, it is two small, the grounding conductor is required by 250.122(B) to be increased in size with the circuit conductors so in this case the grounding conductor will have to be the same size as the circuit conductors.

 

[Rewire]

I am installing 2 -1000w MH lights on a pole approx. 25-30 ft in the air. Each light will have its own pole. 2 lights, 2 poles.
The panel is about 425' away. It is a 120/240 panel and since I want to use as little $ as possible to run the fixtures, I am choosing a multi-tap fixture with 240v connection inside.
The question is this: With the panel being so far away, what is the best way to find the PROPER wire size. I believe it is #6.
Any help would be appreciated.
Thanks, Sparky

P.S.- I don't have amperage info. at this time.

What is the distance between poles?

 

[sparky723]

MH Lites

MH Lites

Many thanks to Bob (Iwire) for his help and understanding.

The reason I was gonna put in a neutral (and the 1.25 pvc) is to accomodate
for a 120v circuit and anything in the future should the customer want something else.

Rewire-I do not know the distance between the poles. The customer hasnt made up his mind where he wants them yet.

 

[sparky723]

Forget the 10 AWG, it is two small, the grounding conductor is required by 250.122(B) to be increased in size with the circuit conductors so in this case the grounding conductor will have to be the same size as the circuit conductors.

It says if I increase the ungrounded conductor to increase the grounding...so why couldnt I run a #10? I am a bit confused...

 

[rt66electric]

future stuff

future stuff

We all know that as soon as the lights go up, someone else needs a recept or RV circuit or something. Be sure to compare your copper costs to the costs of alum urd cable and 1 1/2 conduit. The supply houses sell a lot much 2-2-2-4 that is faily cheap and available. last time I checked it was less expensive to run 90amps alum than 60amp copper.

 

[sparky723]

2-2-2-4?
Thats a bit big huh? I only need #6.

I was gonna throw a #8 set in there for future....

and whats URD?