Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 02-22-2011, 11:57 PM   #1
Member
 
Join Date: Jan 2009
Posts: 47
Share |
Default

Low Voltage LED Lighting


I am in the process of switching my backyard low voltage lighting system over to LED. I have a 400W transformer and I will have twelve 4W lights on a straight run of 12G cable.
1. Is there any danger of using the 400W transformer with a load of only about 50W? I was using this transformer with ten 25W halogen lights and I'd rather not replace it if I don't have to.
2. Is it OK to daisy chain the lights? Since I'm using LED lights, I figured that it would be safe, but I've received conflicting infromation.

Cultcab is offline   Reply With Quote
Old 02-23-2011, 06:08 AM   #2
Tool Geek
 
PaliBob's Avatar
 
Join Date: Jun 2008
Location: Pacific Palisades CA
Posts: 2,490
Default

Low Voltage LED Lighting


1. OK on the Xfmr

2. If You are just replacing incandescent 12V bulbs with the same profile LED bulbs then you just plug them in.

Note. if you are buying these: (click here) 12V LED T10 Wedge bulbs
then note they have mixed reviews.
.

__________________
Disclaimer
& Stay Safe
.....Bob Lavery
PaliBob is offline   Reply With Quote
Old 02-23-2011, 09:36 AM   #3
Member
 
Join Date: Jan 2009
Posts: 47
Default

Low Voltage LED Lighting


Thanks for the reply.

On #2, I'm replacing the cable (from 14G to 12G) and all of the fixtures. I'll need to rewire the lights and instead of using the the plastic connectors that come with the lights, I'd like to use waterproof wire nuts. It seems like it would be easiest to daisy chain them.
Cultcab is offline   Reply With Quote
Old 02-23-2011, 11:55 AM   #4
Member
 
Join Date: Dec 2009
Location: Springfield OH
Posts: 768
Default

Low Voltage LED Lighting


I suggest soldering the connections, THEN using waterproof wire nuts.

One of the nice things about LEDs is the lower current. This makes me wonder if there is much value in replacing all that 14G cable.

LEDs are also less sensitive to voltage variance, as I understand it. They tend to output the same lumens, regardless of whether the voltage is near the top or bottom of operating voltage. This is another bit of evidence that your existing 14g wire may be enough.

Regarding transformers, I understand some of those magnetic transformers can overdrive voltage, especially on startup. Pay attention to be sure you are not doing this with LEDs.
oberkc is offline   Reply With Quote
Old 03-31-2011, 03:52 PM   #5
Newbie
 
Join Date: Mar 2011
Posts: 5
Default

Low Voltage LED Lighting


I can use this on some Utah landscape lighting systems. Thanks
Utah Lighting is offline   Reply With Quote
Old 03-31-2011, 05:37 PM   #6
Member
 
Join Date: Oct 2010
Location: Cairns Australia
Posts: 2,373
Default

Low Voltage LED Lighting


The only minor problem is that,
because the load is rather light for the transformer,
that the output voltage could be a little higher than usual.
How ever this not an insurmountable problem.
With the leds you could use dropper resistor.
I would suggest that you measure the output voltage under load.
If it's a bit high then you could use a dropper of some sort.
The 50w lamps wont like high voltage,
and you will get very short life.

Quote:
Originally Posted by Cultcab View Post
I am in the process of switching my backyard low voltage lighting system over to LED. I have a 400W transformer and I will have twelve 4W lights on a straight run of 12G cable.
1. Is there any danger of using the 400W transformer with a load of only about 50W? I was using this transformer with ten 25W halogen lights and I'd rather not replace it if I don't have to.
2. Is it OK to daisy chain the lights? Since I'm using LED lights, I figured that it would be safe, but I've received conflicting infromation.
dmxtothemax is offline   Reply With Quote
Old 04-01-2011, 01:44 AM   #7
" Euro " electrician
 
frenchelectrican's Avatar
 
Join Date: Apr 2006
Location: WI & France { in France for now }
Posts: 5,369
Default

Low Voltage LED Lighting


Some of the landscape tranfomer do have multitap secondary you can able finetune the voltage setting I know the better one do have them but not the cheap one.

And some of the low voltage transfomer set up make sure you do not have any landscape luminaire too close to the transformer due they will use slightly higher voltage to dealt with voltage drop on the conductors. { the low voltage system is very senstive to voltage drop than line voltage verison is }

Merci.
Marc
__________________
The answer will be based on NEC ( National Electrical code ) or CEC ( Cananda Electrical code ) or ECF ( Electrique Code France )
frenchelectrican is offline   Reply With Quote
Old 04-01-2011, 06:10 PM   #8
Member
 
Join Date: Oct 2010
Location: Cairns Australia
Posts: 2,373
Default

Low Voltage LED Lighting


What sort of conflicting info have you received ?
There are a lot of myths out there,
Mainly from people who think they know,
But have very little real understanding.

Incandesant lights of any type or size,
dont like over voltage.
And will have a short life,as a result.
Better off using slightly less,
for instance a 12v lamp running off 11v.
It will have an extended life span,
but still produce usefull light output.

The same thing applies to LEDS,
Instead of the full current,
Which is around about 20ma,
Reduce it to 15ma.
The life span of the LED is increased.
Simple maths E = I X R
voltage = current x resistance.
dmxtothemax is offline   Reply With Quote
Old 07-12-2012, 05:53 AM   #9
E2 Electrician
 
stickboy1375's Avatar
 
Join Date: Apr 2012
Location: Litchfield, CT
Posts: 4,720
Default

Low Voltage LED Lighting


Quote:
Originally Posted by alice12345 View Post
the way to use 400W transformer with a load of only about 50W is not safe in my mind.
First off, a 400 watt transformer is going to contain two circuits or more, since 400 watts on a single breaker would be a violation of 411.2

The transformer most likely has two 200 watt circuits.
stickboy1375 is offline   Reply With Quote
The Following User Says Thank You to stickboy1375 For This Useful Post:
andrew79 (07-12-2012)
Old 07-12-2012, 06:00 AM   #10
Master Electrician
 
Join Date: Mar 2010
Location: Toronto Ontario
Posts: 1,165
Default

Low Voltage LED Lighting


The wattage on the transformer means squat. If its a 12v secondary or 24v depending on what one you have the wattage is just a rating of how Much you can hook to it. Factoring in the voltage drop on low voltage any startup spikes shouldn't be an issue. Your lights should have a distance rating in the instructions. Running the number twelve is a good idea if your lights are any distance away from the transformer at all.
__________________
Sarcasm is my friend
I'm here to learn too, i do mostly commercial/industrial/new construction and this place is a great way to pick up tips on residential from some good electrical minds. Excuse the spelling, my phone has a mind of it's own.
andrew79 is offline   Reply With Quote
Old 07-12-2012, 07:14 PM   #11
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Default

Low Voltage LED Lighting


that the output voltage could be a little higher than usual.
>Could be up to 25% higher.

With the leds you could use dropper resistor.
>Which could be a low wattage incand. bulb in series with the 'frmr primary winding. Adjust the bulb size for the desired output voltage under load.
Yoyizit is offline   Reply With Quote
Old 07-12-2012, 07:17 PM   #12
E2 Electrician
 
stickboy1375's Avatar
 
Join Date: Apr 2012
Location: Litchfield, CT
Posts: 4,720
Default

Low Voltage LED Lighting


Quote:
Originally Posted by Cultcab View Post
2. Is it OK to daisy chain the lights? Since I'm using LED lights, I figured that it would be safe, but I've received conflicting infromation.
It's all about voltage drop, and i concur since you are using LED, you might be okay, but generally, I run as many home runs as I see fit to distance and load...
stickboy1375 is offline   Reply With Quote
Old 07-12-2012, 07:45 PM   #13
Master Electrician
 
Join Date: Mar 2010
Location: Toronto Ontario
Posts: 1,165
Default

Low Voltage LED Lighting


for 5% drop i get 38ft max for 12v lights and 75 feet max for a 24v system with the number 12 wire. Keep in mind that at a 5% drop that brings the 12 volts down to under ten. and your lights probably won't turn on.
Just an example of how finicky low voltage circuits are for voltage drop. A diode has a set voltage it needs to even turn on. If underpowered it won't just be dim, it won't work at all until you hit that magic number that causes current to jump the dielectric. think of it like a built in switch.
I really hope i'm remembering my electronics in college right
__________________
Sarcasm is my friend
I'm here to learn too, i do mostly commercial/industrial/new construction and this place is a great way to pick up tips on residential from some good electrical minds. Excuse the spelling, my phone has a mind of it's own.
andrew79 is offline   Reply With Quote
Old 07-12-2012, 08:03 PM   #14
Member
 
Join Date: Dec 2009
Location: Springfield OH
Posts: 768
Default

Low Voltage LED Lighting


Voltage drop is dependent on current, as I recall. With LED being much lower current draw, I expect a much lower voltage drop compared to incandescent loads over an equavalent wire distance. 20 amps will have a much higher voltage drop than 2 amps.

I can tell you that I no longer concern myself with special wiring methods for landscape lighting. I have wire runs over 200 feet (12 guage) and I can discern no difference in intensity between lights at either end of the run. They all come on. They look the same. All is well.

I probably have less than 15 watts on any particular run, however.
oberkc is offline   Reply With Quote
Old 07-12-2012, 09:26 PM   #15
Master Electrician
 
Join Date: Mar 2010
Location: Toronto Ontario
Posts: 1,165
Default

Low Voltage LED Lighting


Quote:
Originally Posted by oberkc View Post
Voltage drop is dependent on current, as I recall. With LED being much lower current draw, I expect a much lower voltage drop compared to incandescent loads over an equavalent wire distance. 20 amps will have a much higher voltage drop than 2 amps.

I can tell you that I no longer concern myself with special wiring methods for landscape lighting. I have wire runs over 200 feet (12 guage) and I can discern no difference in intensity between lights at either end of the run. They all come on. They look the same. All is well.

I probably have less than 15 watts on any particular run, however.
he's going to be running at 4A so the voltage drop is easy to figure out. voltage drop in low voltage makes a bigger difference because when you lose 5% of 12v it makes a way bigger difference then when you lose 5% of 120v.

__________________
Sarcasm is my friend
I'm here to learn too, i do mostly commercial/industrial/new construction and this place is a great way to pick up tips on residential from some good electrical minds. Excuse the spelling, my phone has a mind of it's own.
andrew79 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Low voltage landscape lighting rjniles Landscaping & Lawn Care 2 09-24-2010 09:55 AM
low voltage wiring for niche lighting 8roty Electrical 4 01-16-2010 07:17 AM
How to get low voltage through a corner pantry for cabinet lighting? ClemsonJeeper Electrical 7 11-11-2009 09:44 PM
New recessed lighting: Line Voltage vs. low voltage hyunelan2 Electrical 0 10-12-2009 12:25 PM
Low Voltage Lighting Bulb Life IdahoBob Electrical 2 12-23-2007 12:24 AM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.