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Old 02-12-2013, 01:50 PM   #16
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voltage drop calculations and parking lot lights


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Originally Posted by mpoulton View Post
It has half the voltage drop, but 1/4 of the voltage drop *problem*. The important parameter with voltage drop is not the absolute drop in voltage (5V or 10V) but the percentage reduction in supply voltage (2% vs. 8%). Doubling the voltage reduces the percentage voltage drop by a factor of four.
Thank you. I thought "1/4 as severe" was pretty clear.

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Old 02-12-2013, 09:51 PM   #17
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voltage drop calculations and parking lot lights


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If I had been forced to use 120 volts I would have compensated in the first run to the center of the parking lot between poles with larger wire, then used 12 awg to each pole. I think a most 20 amp breakers would takeup to a #8 awg. Anyway I would play with wire sizes to see if that would get me reasonable Vd using 120 volts.

All this 12 awg and poles are in place but I take it that it is not in operation yet.
Thanks everybody for your help thus far!

Yes, #12 is in place, but the lights are not in operation yet. They want to use a timer on the inside to keep the lights off on nights when they are not there, and that has yet to be put in place.

In terms of voltage drop and playing with wires sizes, what voltage drop should be deemed reasonable for 120V? 3%? I seriously do not understand why they did not wire them for 240V. Otherwise, it is going to be be difficult to get the Vd under or around even 5% unless you use #8 from the panel all the way to the base of the poles (that would give Vd~5.1% by my calculations).
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Old 02-12-2013, 10:17 PM   #18
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voltage drop calculations and parking lot lights


If the wire is in place but not yet hooked up why not just wire them for 240v instead of 120v?
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Old 02-13-2013, 12:15 AM   #19
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voltage drop calculations and parking lot lights


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Originally Posted by Squidbilly View Post
Thanks everybody for your help thus far!

Yes, #12 is in place, but the lights are not in operation yet. They want to use a timer on the inside to keep the lights off on nights when they are not there, and that has yet to be put in place.

If not hooked up yet it will be good time to reconferaged to 240 volts that is not super hard to do that but I know someone will have to go back up to the pole topper and change the connection and this is the only surefire way you can slove the issue with exsting conductors what ya got there.

Second thing If ya going to use the timer get one that rated to run on 240 volts ( there are few verison aviable )

And as I mention before make sure nothing else is hooked up to this circuit when going from 120 volts to 240 volts even 208 volts if your church have them that will work just fine as well.


In terms of voltage drop and playing with wires sizes, what voltage drop should be deemed reasonable for 120V? 3%? I seriously do not understand why they did not wire them for 240V. Otherwise, it is going to be be difficult to get the Vd under or around even 5% unless you use #8 from the panel all the way to the base of the poles (that would give Vd~5.1% by my calculations).
Normally I useally sized the conductor with 5% Voltage drop which it is typical very few items I will have tighter voltage drop but not used often.

Most HID lumiaires will work 5% voltage drop without much effort but anything more than 5% will created a new cans of " worms "

The other thing it will change the game a little due few mention before is use larger conductor and I am not too suprised that you may run the luminarie more than 3 hours easy so it will treat as contionous useage.

So that why few of us mention upsizing the conductor in first place.

Merci,
Marc
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Old 02-19-2013, 10:11 PM   #20
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voltage drop calculations and parking lot lights


Thanks again for all the responses.

Just an update .....

Against my strongest recommendations, they went ahead with the wiring as is (#12 all the way) and had the local power company stand up the poles. Upon testing them tonight, none of the four lights will burn. Now, they are back to me asking why.
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Old 02-20-2013, 01:01 AM   #21
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voltage drop calculations and parking lot lights


We are all wondering why the lights are not wired 240 volts single phase when you have all the wires necessary to change the wiring to that configuration. You will need to change the breaker to a double pole that's all. this of course will depend on if your using 120/240 single phase or a 120Y208 3 phase panel.
Second thing on the m400 ballast your going to have a series of tap wires each wire is for a certain supply voltage. You need to make sure they have the right tap wire chosen. The others are capped and not used.
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Old 02-20-2013, 01:12 AM   #22
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We are all wondering why the lights are not wired 240 volts single phase when you have all the wires necessary to change the wiring to that configuration. You will need to change the breaker to a double pole that's all. this of course will depend on if your using 120/240 single phase or a 120Y208 3 phase panel.
Second thing on the m400 ballast your going to have a series of tap wires each wire is for a certain supply voltage. You need to make sure they have the right tap wire chosen. The others are capped and not used.
That was my recommendation: wire the luminaires for 240V and run #10 to the center point.

For some reason, they completely ignored both and went ahead with #12 wire and had the fixtures (@ 120V) mounted and the poles erected via the local power company. I got a call tonight from the pastor that the fixtures would not light. Reluctantly, I went over and confirmed voltage at the base of the both poles. There wasn't much more that I could do at the time.

The voltage drop is indeed quite excessive (~11.5%), but their should at least be some response if the fixtures had been wired properly ... right?

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Old 02-20-2013, 02:34 AM   #23
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voltage drop calculations and parking lot lights


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That was my recommendation: wire the luminaires for 240V and run #10 to the center point.

For some reason, they completely ignored both and went ahead with #12 wire and had the fixtures (@ 120V) mounted and the poles erected via the local power company. I got a call tonight from the pastor that the fixtures would not light. Reluctantly, I went over and confirmed voltage at the base of the both poles. There wasn't much more that I could do at the time.

The voltage drop is indeed quite excessive (~11.5%), but their should at least be some response if the fixtures had been wired properly ... right?
Depends on the type ballast and the voltage drop it will tolerate and still start the lamp. I would suspect a 400 watt multi tap ballast would be of auto regulater type. I would guess you would see something at least the attempt to strike the arc in the bulb. However excessive voltage drop outside the operating range of the ballast specifications label may prevent any starting of the lamp. Or the ballast is miswired .... who wired the ballasts to the supply?

Might look thru this and see if it helps ....

https://secure.ge-lightingsystems.co...llast_data.pdf
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Old 02-20-2013, 06:58 AM   #24
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voltage drop calculations and parking lot lights


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Originally Posted by Squidbilly View Post
Thanks again for all the responses.

Just an update .....

Against my strongest recommendations, they went ahead with the wiring as is (#12 all the way) and had the local power company stand up the poles. Upon testing them tonight, none of the four lights will burn. Now, they are back to me asking why.
It could be anything. From a bad photocell to miswired fixtures to voltage drop.

As a side question, why would the POCO set the poles?
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Old 02-20-2013, 09:02 AM   #25
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It could be anything. From a bad photocell to miswired fixtures to voltage drop.

As a side question, why would the POCO set the poles?
We are talking a small church here .... maybe 30 or 40 .... a majority of which are older. The power company did it on a volunteer basis.
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Old 02-20-2013, 12:58 PM   #26
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voltage drop calculations and parking lot lights


FYI - I've never thought about it, but there are some BIG parking lots out there! (Very long wire runs!)

I did some poking around and see a 277 volt option is common with these fixtures. (Like at following link) And of course the higher the voltage, the smaller gauge wire you can use for these long distances.

http://www.warehouse-lighting.com/st...-120-volt.aspx
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Old 02-20-2013, 01:39 PM   #27
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voltage drop calculations and parking lot lights


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I did some poking around and see a 277 volt option is common with these fixtures.
True, but most churches are not going to have 277V available. That is why everyone has been talking 240V.
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Old 02-20-2013, 02:04 PM   #28
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voltage drop calculations and parking lot lights


I contacted the power company today, and they wired the luminaires for 208V. So naturally, they were not going to light at 120V. I don't know why this wasn't communicated before now, but I am glad to see somebody knew #12 was too small for those fixtures @ 120V. So, some changes at the panel, and they should have lights. I will post back with results. Thanks again.
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Old 02-20-2013, 04:09 PM   #29
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Make sure you have 208 available.
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Old 02-20-2013, 04:24 PM   #30
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I doubt if you have 208 in a small venue like you described earlier. I suspect you are going to need to grow wings [or beg your POCO buddies back out with their bucket truck] to change the taps on the ballasts to 240V.

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