# low voltage step up, to compensate for voltage drop???



## mikewillnot (Apr 2, 2013)

I'm modifying a pre-existing landscape installation, per the request of a regular customer. 600 watt multi-tap (12, 13, 14, 15v) controller, about 50% loaded, existing lighting, mixed sizes, grouped in front area of house. Wants ugly controller moved to back of house, and more lights installed in back. I ran the new wire, moved the controller temporarily and did a test powering the existing front lights. Lights run at about 40% brightness. 

I'm thinking about a 12v to 24v step-up transformer, but no luck finding one so far. I know, I know... 120v-12v, then 12v back up to 24, etc... not smart. 

LV landscape lighting is not my usual area, and to my knowledge there aren't many specialists around here. I'd appreciate any suggestions very much.


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## SteveBayshore (Apr 7, 2013)

What is the voltage at the end of the circuit when all the lights are on? What is the voltage at the transformer terminals? Might be voltage drop from conductors being undersized for length. Not a good idea to overcome VD by increasing the voltage that much.


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## mikewillnot (Apr 2, 2013)

I'm going back to the site tomorrow; I'll get the readings.
I was thinking about finding brighter bulbs, maybe LED, but haven't found much out there. Everything seems to be "equivalent," i.e. same lumens as the existing choices, halogen etc, more or less.


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## alambre (Jan 29, 2012)

voltage drop=((length of wire X watts) X 2))/cable constant

cable constants
12AWG=7500
10AWG=11920

Halogen lamps need 10.8 to 12 volts to operate properly
Change to LED lamps and your problems go away


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## BababooeyHTJ (May 31, 2013)

What size wire did you run?


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## mikewillnot (Apr 2, 2013)

12.
Voltage at the tap in question: 12 
voltage at end of string: 4.5
Engineers at factory agree with previous poster and said emphatically that LED's will fix the problem. I'm currently waiting for the customer to bite the bullet.


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## pete87 (Oct 22, 2012)

mikewillnot said:


> I'm modifying a pre-existing landscape installation, per the request of a regular customer. 600 watt multi-tap (12, 13, 14, 15v) controller, about 50% loaded, existing lighting, mixed sizes, grouped in front area of house. Wants ugly controller moved to back of house, and more lights installed in back. I ran the new wire, moved the controller temporarily and did a test powering the existing front lights. Lights run at about 40% brightness.
> 
> 
> LV landscape lighting is not my usual area, and to my knowledge there aren't many specialists around here. I'd appreciate any suggestions very much.




When you ran new wire to Back of House ... 

Same Size wire and added major footage to the run ? .... OUCH !

The 15v tap might have provided a little umpahg !


Pete


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## mikewillnot (Apr 2, 2013)

Actually, I moved the controller to the back and ran the wire for the new lights in the back (also #12, similar length of run overall), but haven't added any lights there yet. The only load at this point is the long run to the front, and the cluster there. The transformer has two sets of taps, each including 12, 13, 14, and 15v. I have the front cluster combined and connected via a long run of wire to one of the two 15v taps. That's the only load at present.

still waiting for the OK to switch the front lights to LED (about $500 in bulbs).


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## macmikeman (Jan 23, 2007)

In situations where voltage drop is the concern, generally speaking the size required for a buck and boost type transformer to match the load is well above the expense of just getting larger wire out to the site. Where they are valuable is when you need to get a higher voltage then what the utility supplies to the building.


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## davis9 (Mar 21, 2009)

What about this type? 

http://www.ebay.com/itm/600-Watt-Lo...ing-Stainless-Steel-Transformer-/370910359778


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## pete87 (Oct 22, 2012)

still waiting for the OK to switch the front lights to LED (about $500 in bulbs).[/QUOTE]



Wow , pricey bulbs .



Pete


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## mikewillnot (Apr 2, 2013)

Sometimes it seems like the people with the most money are the tightest with it. Pennywise... etc.


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## mikewillnot (Apr 2, 2013)

Of course, that may be part of why they have more money.
Hmmmm.


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## hardworkingstiff (Jan 22, 2007)

mikewillnot said:


> LV landscape lighting is not my usual area, and to my knowledge there aren't many specialists around here. I'd appreciate any suggestions very much.


1) Did you do a site layout and VD calculations? 

2) I've read that with LV lighting it is often more desireable to run from the transformer to a middle point then out from there to each light. I think it's called a star configuration instead of looping from light to light like you do for house receptacles. Think of it like a wagon wheel with the mid point being the hub and the spokes are the runs to the individual lights.

By using the star connection method, all the lights should receive close to the same voltage, especially if the conductor length from the mid point to the lights are the same for each light.

If you wire them like house receptacles (going from light to light instead of the star method) the lights at the beginning of the circuit will received more volts than the end of the circuit (like your seeing). 

If you try to compensate for VD by raising the voltage instead of increasing the wire size, when one lamp burns out, the voltage on the rest of the lights increases. This can in turn cause the next weakest lamp to burn out which will raise the voltage again. Once 2 or 3 of the lamps burn out, the voltage is probably too high for the lamps used and can wind up burning out all of the lamps.

LV lighting is more involved than what the box stores tell customers.


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## bobbyho (Oct 15, 2007)

If you are stuck with halogen, you need to be between 10.8 and 11.5 volts. Any less and the lamp yellows and any more you may experience shorter life expectancy out of the lamp. I am 99.5% LED on all lighting installs now because the color temps are awesome, beam spreads are great, liife expectancy is outstanding and the voltage window is incredibly flexible.
I don't know if you stated how far you have to go but one option may be is to run a 12/2 back to the transformer. This may help with the voltage drop. Ideally, change them out to LED. Feel free to PM me if you have any other questions. We do a lot of landscape lighting. I find most electricians want nothing to do with it as it is dirty and exhausting work. If you told me a few years ago that I would love it, I would have said you are crazy. It is now my favorite thing to do.


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## hardworkingstiff (Jan 22, 2007)

bobbyho said:


> I don't know if you stated how far you have to go but one option may be is to run a 12/2 back to the transformer. This may help with the voltage drop.


I think he already stated he's using 12.


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## hardworkingstiff (Jan 22, 2007)

mikewillnot said:


> Voltage at the tap in question: 12
> voltage at end of string: 4.5


Unless you have a bunch of lamps, it almost sounds like you might have some high resistance connections.


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## mikewillnot (Apr 2, 2013)

LEDs worked great.


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## Dpm1132 (Oct 18, 2017)

If old install was perfect brightness then add another transformer to other half or new section


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