Long lighting runs - #12 120v

[Moosifer]

120v bollard runs. I have a customer that wants 3 different 600ft runs for 120v bollards.

They have an existing 600ft run with about 30 bollards on #10 120v. How does that work with voltage drop?

I'm trying to figure out how to do the other three (600ft each) at 120v with 30 bollards each and probably 5v led bulbs without using giant wire.
I seem to see a lot of 120v runs for lighting that use #10 or #12. I don't get it. We don't do a lot of new installations of outdoor lighting so I'm not going to pretend I know what to do. We fix quite a bit of it. 277v would seem like a better option but they want 120v.

Do they just ignore voltage drop? Any help would be appreciated. This is on a boardwalk around a lake.

 

[xformer]

120v bollard runs. I have a customer that wants 3 different 600ft runs for 120v bollards.

They have an existing 600ft run with about 30 bollards on #10 120v. How does that work with voltage drop?

I'm trying to figure out how to do the other three (600ft each) at 120v with 30 bollards each and probably 5v led bulbs without using giant wire.
I seem to see a lot of 120v runs for lighting that use #10 or #12. I don't get it. We don't do a lot of new installations of outdoor lighting so I'm not going to pretend I know what to do. We fix quite a bit of it. 277v would seem like a better option but they want 120v.

Do they just ignore voltage drop? Any help would be appreciated. This is on a boardwalk around a lake.

What do you come up with when you do a voltage drop Calc?

 

[ptonsparky]

As suggested, you really need to do a VD calculation. We have no idea what the specs of your fixtures are. 5 volt bulbs doesn't tell us a lot.

 

[Moosifer]

Ok perhaps this is where my ignorance comes into play. If I pull up a table for 15a circuit with a 3% drop at 665ft it says I need #2. That is my starting and ending point of my research and why I'm asking what I'm missing.

 

[Charged]

Other people mention it a lot and I agree southwire has a pretty good view voltage drop calculator on there website. The table your looking at is probably doing the max load on that circuit , you need the fixture wattage and come up with a more accurate load to plug in.

 

[wwhitney]

I'm trying to figure out how to do the other three (600ft each) at 120v with 30 bollards each and probably 5v led bulbs without using giant wire.

What is the wattage of the LED bulbs (really we just need the 120V current of each bollard)? If you meant 5W, then I would think that #12 or #10 for 30 of them over 600 ft is quite plausible, that would only be 150W or 1.25A total.

Cheers, Wayne

 

[xformer]

Ok perhaps this is where my ignorance comes into play. If I pull up a table for 15a circuit with a 3% drop at 665ft it says I need #2. That is my starting and ending point of my research and why I'm asking what I'm missing.

Use actual connected load.

 

[Moosifer]

Ohhhh. Ok, thanks everyone. I guess I'm not dealing with parking light poles. Fixed mindset.

 

[LarryFine]

If I pull up a table for 15a circuit with a 3% drop at 665ft it says I need #2.

That presumes an actual 15a load, and at the far end of that run. Voltage drop is dependent on only two things: circuit impedance and load current. That's why you must know your actual load, and not the circuit rating.

Think about it in the real world. The last length of wire will have the current of only one light on it, the one before that, only two, etc. That's how you would calculate the voltage drop using long math one run at a time.

There are calculators available as mentioned above, but I haven't used one in a long time, so I can't recommend one. I generally opt for long feeders over long circuits, and I've kinda developed instincts for voltage drop.

 

[James L]

30 bulbs 5w each only poses about 2% voltage drop with #12 on 120v circuit

 

[tom baker]

Don’t use the lamp amps, use the driver input amps.

 

[Charged]

Is there a big difference with LEDs? I usually roll with whatever is published on the cut sheet, however it’s given.
With HID and fluorescents , I used to look at a ballast book to get the input amps but haven’t found a specific way to do it with LEDs.
Is there any that can get you in trouble like the higher wattage HIDs?

 

[Dennis Alwon]

Led's drivers usually have a wide range of acceptable voltages so my guess is 10 mis more than enough. I guess the worst case scenario is the farthest ones will light dimmer but I am not sure that is true with drivers involved as long as the voltage is in acceptable range.

 

[James L]

Don’t use the lamp amps, use the driver input amps.

If it's 120v fixtures, the LED lamps should have the driver current included?

I'm assuming OP meant 5w instead of 5v

 

[kwired]

Ohhhh. Ok, thanks everyone. I guess I'm not dealing with parking light poles. Fixed mindset.

Parking lot light poles isn't really any different.

Keep in mind in most instances you are going from one light to the next with your conductors. every light leave to go to the next hit you are reducing the load by how much one draws, so voltage drop isn't the same throughout the entire circuit but is still additive as you go, if that makes any sense.

You may find you need larger conductor in the first sections of the run then you do at the end of the run simply because load is less at the end of the run than at the beginning. So you basically need to calculate each segment of the run separately if you don't want to run a large conductor the entire length yet want to maintain a certain level of voltage drop.