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I have a customer who has a 1,600 long driveway lined with sculptures they want lit up. We're gonna use low voltage LED up-lights. I'm not sure how to wire the receptacles for the transformers. I know there is at least 20amp at the entrance of the driveway, there's a barn with a panel roughly in the middle, and the house with a panel on the end of the driveway. With voltage drop, what's the best way to wire this? Should I just do one circuit coming from the house that will be almost 1,600 feet long? How would I do that? We're gonna have the driveway tunneled in at least one spot to be able to run wires through. On the drawing, the Xs are sculptures. Thanks! -John
 

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These people clearly have plenty of money. I would be worried about control if they were fed from multiple locations. Maybe start at the barn and go each direction.
 

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These people clearly have plenty of money. I would be worried about control if they were fed from multiple locations. Maybe start at the barn and go each direction.
WAY TOO MUCH MONEY! lol

How would you go each way? Lets say I go from the barn with two 20 amp circuits. One up, and one down the driveway. We can use the tunnels underneath for the low voltage stuff. If I run one 20 amp circuit 800' what size wire will it have to be and how would I attach it to the receptacle?
 

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You can change wire size in a run as long as smallest wire is sized for the breaker, so that's not a problem.

Use a voltage drop calculator. We don't know your loads.

And the lighting should come with information on how far you can run that low voltage. You may indeed need quite a few transformers.
 

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Hackenschmidt
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If you run a 240V circuit on #12 wire, that's nice and easy, but voltage drops to 164V at the end of the 1600' line.

However, there are lots of switching power supplies / LED drivers that are fine with a wide range of voltages, look at this one rated for 100V - 240V -

https://www.hero-led.com/led-transformers-waterproof-ip68-led-driver-12v-dc-4a-48-watts-p-5530.html

(Now that one is pluggable which would be an issue, I'd want one that's hardwired and listed for the necessary voltage range.)

This kind of power supply handles the voltage drop for you. So I'd make sure I used lights I could use with this kind of power supply.
 

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You should forget the notion of low voltage. Low voltage is for (comparatively) short runs, shallow dug cables and inexpensively (IE - cheap) fixtures.



What you have is more comparable to a runway- and runways are lit by 6000v circuits feeding a step down isolation transformer in each fixture wired in series. (To combat voltage drop.)



Find line voltage LED fixtures capable of a 100-240v input as Splatz says. Feed from the barn. KISS- (keep it simple stupid) Keep the control issue from getting insane by using a simple 2-pole timer or a photocell with a contactor. Do not entertain any ideas or suggestions of dimming or switching schemes from the house.


Use in-ground handhole splice boxes at each fixture or group of fixtures. No receptacles - no transformers- no stub ups or boxes nothing protruding from the ground.
 

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You should forget the notion of low voltage. Low voltage is for (comparatively) short runs, shallow dug cables and inexpensively (IE - cheap) fixtures.



What you have is more comparable to a runway- and runways are lit by 6000v circuits feeding a step down isolation transformer in each fixture wired in series. (To combat voltage drop.)



Find line voltage LED fixtures capable of a 100-240v input as Splatz says. Feed from the barn. KISS- (keep it simple stupid) Keep the control issue from getting insane by using a simple 2-pole timer or a photocell with a contactor. Do not entertain any ideas or suggestions of dimming or switching schemes from the house.


Use in-ground handhole splice boxes at each fixture or group of fixtures. No receptacles - no transformers- no stub ups or boxes nothing protruding from the ground.
I agree with him on the set up and try to get one with highest input voltage then sized the conductor to dealt with voltage drop issue you may end up run at least two maybe three different size conductors depending on distance and the load ya throwing on it.

start at centre due you mention almost 250 meters of run each way.,, so that is hellva a good run there.

keep it simple maybe you may need to split in two circuits to reduce the loading issue with the circuit on very long run.

try to use the alum conductors if you can it far much cheaper but just becarefull with it.,, just prepared for the correct set up then ya good to go.

I am tempting to say this but try this idea get a 240X480 volt single phase transfomer and boost it up for long runs then use smaller down step transformer for local lights ( can be either 120 or 240 volt verison ) with this set up you can use smaller conductors but only one qurik .,, no receptales only hardwired .,,

It is common in my area to have super long runs to set up on 400 or 480 volts that useally take care the damm voltage drop issue.
 

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I would add a receptacle ever hundred feet. I would also use no 8 awg or larger but you really need to know the wattage of the system
 

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How would you attach the #8 to the receptacle?
You don't. You'll have to tail it with a wire size that is appropriate for the OCPD and the wire gauge the receptacle will accept (here the receptacles we use are #14 thru #10)

Sent from my Samsung using Tapatalk
 

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When I made that suggestion I was thinking #12 because it's relatively cheap and readily available in direct burial wire. I pictured running a 240V "bus" from top to bottom through handholes at each statue with a stub / pedestal by each handhole to house the power supply. A tap and run connection at each handhole to feed the power supply, then #12 direct burial again at 12V to the low voltage LED uplights for that statue. You could use at least 150 watts per statue and keep the load under 16 amps, that should be more than enough for LED uplighting unless each statue is the size of the Lincoln memorial. I think this would be very hard to beat bang for the buck.



Going up from there - it would be nice to have a receptacle at every statue. You could do some complicated distribution but would all the transformers etc. pay off better than a ridiculously oversized wire, something crazy like 1/0 Al for a 20A receptacle circuit?



It would be nice to have conduit and it might make sense to have a little duct bank with some spares. Realistically they are going to have some loads at the end of that driveway, bigger lights, maybe a gate, holiday lights etc. How rich did you say these people were again?
 

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If you run low volt lighting more than 100' you are asking for trouble. In my humble opinion I would go with 120 volt fixtures. I would also think very hard about how to control them because if different sections come on and off at different time they are gonna bitch.

Either way that is a nice little $10K job.
 

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Discussion Starter · #16 ·
When I made that suggestion I was thinking #12 because it's relatively cheap and readily available in direct burial wire. I pictured running a 240V ?
How would I get the 240v to 120 for a plug to the transformer or if we decided to do 120v light fixtures?

And apparently they had some world known sculpture make all these things custom from them. Everything from dragons to Yoda!
 

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FWIW, might be a good idea to consult with an EE firm or an EE with a PE stamp (that does lighting). That way you know you have done your homework. Pass fee on to customer. Worst case they design (draw up prints, specs etc) & you install.
 
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How would I get the 240v to 120 for a plug to the transformer or if we decided to do 120v light fixtures?

And apparently they had some world known sculpture make all these things custom from them. Everything from dragons to Yoda!
I think that would be a problem, that's why I was thinking hard wired power supplies / transformers / drivers whatever you want to call them, that are rated for 240V input, rather than something pluggable.
 

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FWIW, might be a good idea to consult with an EE firm or an EE with a PE stamp (that does lighting). That way you know you have done your homework. Pass fee on to customer. Worst case they design (draw up prints, specs etc) & you install.
It's just lighting with voltage drop calc thrown in??

In our shop, we'd design it and keep the fee ourselves. I figured that's why a good portion of us on this forum had our masters or supervisors licenses??

The only thing holding the original poster back, is picking a direction and working the calcs.

No one knows the site or what the customer wants, except him. You can piddle around forever, or get to picking a fixture type, which gives you your loads and then start crunching numbers.

This would normally be done in less than an hour once you play with wire sizes, cu or al, etc.
 

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This job can be done using low voltage landscaping lighting. The voltage drop is not that bad. The key is using the correct product. Doing lighting today is so easy. I will use the example below to give you some help.

Light used in this example a 8 watt integrated (60,000 hour) cast brass 2700k -500 lumes up light.Light output can be adjusted from 20% to 100% using remote at each light. Shipped at 50% output.

https://www.amplighting.com/g2-amp-one-controlpro-500-led-spotlight/p/AAL-3001IR-25-BBZ#tab-3

Transformer used in this example is a 900 watt 12 to 22 volt.

https://www.amplighting.com/low-voltage-lighting-multitap-transformer-outdoor-900/p/VTR-900P#tab-3

Voltage drop can be handled three ways. First at the transformer you have 12 to 22 volts to use, second the size of the wire. And third LED lights have a wide range of working voltages.Most are from 6 to 18 volts. Don't use the low or high voltages just aim for the middle. How do you do this?

The transformer is mounted on the barn. Using the opposite side of the road in this example.There are 10 lights on that side of road. Bore under road between light 5 and 6. You will wire 5 lights with one run of wire. You have 900 feet of wire to the five lights.You have a total of 40 watts(5x8).
900 x 40=36000
36000/by wire constant below = voltage drop
#16/2 2200
#14/2 3500
#12/2 7490
#10/2 11920
#8/2 18960

Answer from above using each wire size.(target is the middle voltage of 6 to 18 volts)
#16/2 36000/2200 = 16.36 voltage drop. Not good even if you use the 22 volt tap you only have 3.64 volts.
#14/2 36000/3500 = 10.28 voltage drop. Round up to 11 volts.Not good no room for add on or adjustment. Use 22 tap gives you 11 volts.
#12/2 36000/7490 = 4.80 voltage drop. Round up to 5. Use the 17 volt tap gives you 12 volts.
#10/2 36000/11920 = 3.02 voltage drop. Use 15 volt tap gives you 12 volts.
#8/2 36000/18960 = 1.89 voltage drop. Round up to 2. Use 14 volt tap gives you 12 volts.

Note- Transformers come in 12 to 15 or 12 to 22 volts. The one i listed is 900 watt 12 to 22 which is over kill for your job. This type is a little hard to find in a 300 or 600 watt but can be found. Just make sure you have secondary protection on the transformer. Make sure it has large taps. A 600 watt transformer will have two commons (circuits)a 300 will have one.I see this job as 4 wires runs so make sure the taps are big enough to hold the wires used. Each common will have 25 amp reset able breaker. If using a 300 watt all four wires will be in one common tap.This is often over looked. The other wire will go to the proper voltage tap.

I hope that helps.

Remember landscapers and there toys are your enemy.:vs_OMG:

There is so much more to installing this. Have questions just ask.

Post some pics.
 
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