Outdoor LED Power Supply Questions

[pete_c]

Over the last two years or so I have been converting my outdoor mostly Halogen 12VAC outdoor lighting to LED; a bit at a time.

The current set up is driving by 4 1000 Watt Toroidal multitap/multivoltage commercial landscape transformers mounted inside of the home to one side of the fuse panel (maybe 15 feet away) each one with an individual breaker in the panel.

The wiring is all 12/14 guage to multiple small zones outside. All of the current new LED lighting is 12VDC/AC anwhere from 1/2 watt to 4 watt LED lighting. For example the adjacent to the front of the house lighting is divided into like 5 zones with 5 separate home wired feeds.

I'm looking to start switching over the LED lighting zone by zone to smaller 12VDC transformers and looking for suggestions.

Is there such a 12VDC multiline distributed voltage type transformer I can utilize? I am today using one 12 camera PS with individual fuse links. Is there something similiar with more amperage per load made for LED lighting available?

I'm looking to alleviate a bit of wall clutter (the four commercial toroidal transformers have large footprints), power and trying to keep separately fused links for each zone.

I found a relatively small 60 Watt 12VDC PS. Could I just put a number of these across a piece of plywood to supply power to the LEDs?

How does the 12VDC PS work with multiple runs that are over 200 feet?

Has anyone done anything like this yet?

 

[tmbrown97]

One thing I noticed - is that if you switch to DC it seems hard to find multitap transformers; the multitap 12VAC ones typically have taps ranging from 12-15V to account for voltage loss.

If you're not worried about voltage loss and want to roll your own, it's doable - there are all kinds of camera or even boat/rv distribution panels for 12V that are fused/PTC protected. To guide you any further though we need an idea of the amperage per "leg" you'd expect, and how many of those "legs" you'd need.

I've used those transformers you show above to drive LED strips - they seem to work fine - no issues yet.

 

[pete_c]

Yes; the 12VAC multitap ones that I am using have multiple 12-15 VAC taps and each circuit has its own breaker to further subdivide the zones which is great for isolation of each of the LV zones.

So far I am not using anything greater than 4 watts; but its a real mix of .5, 1, 3, and 4 watt LED 12VAC lamps. I'm now removing and replacing the 8 year fixtures with new more robust workable with LED fixtures.

I was going to just test out one zone.

Curious what type of DC voltage loss would I see on say a 100 foot run of 12 guage wire with say 5 1 watt LED lamps on it? Would it be similiar to the AC voltage loss I see today?

 

[JimS]

Pete,

What have you been using for fixtures or are you using LED bulbs that are made to replace the AC bulbs? And where are you getting them? We have a number of halogen and incandescent (4 and 7W) that I would like to convert. I also am having trouble with the power taps because they just stab into the side of the wire and aren't sealed - planned to redo those with sealant filled wire nuts.

The loss for #12 with 5W of load will be pretty small. Are you saying the LED load is the same as the AC load? AC and DC voltage drop in the wires is figured the same way.

Here is a site to calculate:
http://www.csgnetwork.com/voltagedropcalc.html

It didn't allow me to enter 12V so I selected 24. The voltage drop only depends on current, not voltage.
5w is 5/12 = .417A. Putting in the numbers for #12 wire, 100ft gives 0.2V drop.

 

[pete_c]

Thanks Jim

I am using all 12VAC/DC LED bulbs replacing both halogen and incandescent bayonet type lamps. I'm also starting to replace all of the outdoor fixtures that I don't really like with a more robust easy to convert over to LED fixture. I found a Malibu lamp well contructed and suited for LED. I ended up purchasing these in bulk packs of 12 lamps per pack.

I started with one zone about 2 years ago and bulbs there have been functioning fine. This year purchased about 10 different style 12VAC/DC LED lamps (80 or so - to play with) and have changed over 4-5 more zones. Mostly to play with the different styles of LED outdoor lamps. All purchases from Ebay/Imported. Many bulk purchases.

The LED load and totals per zone are much less than the halogen. Some zones had a "few" and mixture of 10 Watt, 20 Watt and 35 Watt halogens. Now say one zone with all LEDs is bringing the total to maybe 20 watts if anything. I do not have mixed zones; when doing a lighting zone I have replaced all of the lamps in the zone with LEDs.

The lighting housing is mostly malibu and kichler. I have modified the kichler lights to accomodate LEDs. I did find a tiny .5 watt 12VAC/DC LED lamp which works great at replacing the little 10 watt Halogens I had in these mini all glass lantern style LV lighting.

I have just a few trees and they each had facing up 35 or 50 watt spots. I've changed these over to 4 watt LEDs and they look nice color wise and as bright as the previous spots were.

Initially I used the outdoor wire taps. Over the years I have replaced these with just soldered connections; one by one. Whenever I would work on one zone I would replace the taps. It was a bit difficult because they are all mostly under the stone and the fabric over the dirt.

So with minimal LED loads I shouldn't really be concerned with voltage drops on the 100 foot 12 guage runs?

 

[JimS]

So with minimal LED loads I shouldn't really be concerned with voltage drops on the 100 foot 12 guage runs?

I would say so. It doesn't seem like your drop will be much and the switch to LEDs will make it less than before.

Soldering the connections is an interesting idea. It could be done without needing addition length on the main run. If I do wire nuts I will have to have two splices to get some additional length to work with. How did (if you did) seal the connections? The only way I can see to effectively seal them is a method I have seen used on telephone line splices - they use a container shaped sort of like a sausage to pour a thick material into. The material sets up and bonds to the wire insulation "potting" the splice area.

One other point of failure I have seen is occasional bad connections at the bulb base. Wiggling the bulb fixes it but I thought I might solder LED bulbs in to eliminate that issue.

I would be very interested to know the particular replacement bulbs and fixtures you are using. LEDs do fail after time, especially if run too hot so I am reluctant to buy ones with questionable reliability. Anyone can claim they last...

 

[pete_c]

Thank you Jim.

I tapped into the main feed and spliced the wires about 4 inches apart and just taped the solder joints with a thicker electrical tape.

All of the connections have been soldered now for about 6-7-8 years and have held up just fine. The taps started to fail within a year of installation. I had purchased the block style taps. The ones that came with the compression style taps I just cut and replaced with the block tap initially.

The test zone has a mix of 12 lamps. Bollard, mushroom top and a couple of small spots. I used little mini MR11 multi SMD LED mounted warm white lamps for these (maybe 5 SMD LEDs). The little spotlights are of the 3 cree style spots in the set.

I'll have to check but they've been in place for more than a year now.

The Kichler lamps initially had a sort of bayonet mount for a 7 watt bulb. I replaced the lamp mounts initially to convert them to halogen with an MR11 porclein base a few years back.

I am still playing with different style LED lamps. The prices are lower than when I purchased the first zone test LEDs.

I have these little mini glass laterns that originall used 10 watt halogen bulbs. I am currently testing a little mini 1 LED lamp. The light is a little bit less bright than the 10 watt bulb. I have never seen anything like this little LED lamp.

 

[oberkc]

I have replaced ALL my incandescent landscape lamps with LED. This started about three years ago. So far, no lamp failures at all.

I used four, 50W power supplies similar in appearance to



Mine came from superbright LED (web page). Mine are all mounted inside, with each controlled by an insteon relay module. Using a kill-a-watt, I measure total power consumption to be less than 50watts, adding all four.

I also understand that one needs to be less concerned with voltage drop over long runs. So long that voltage remains within the operating range of the LED, then it tends to work well. My experience tends to confirm this. I have runs as long as 300 feet, with no discernable difference in light output levels. I have made no attempt to balance voltage using special wiring techniques.

Connections for each fixture are ALL soldered, then capped with silicone-filled wire nuts. There are other methods that may work, but also some that don't (pierce-point connectors, for one).

 

[pete_c]

Thank-you oberkc.

I'm thinking my longest LV runs are probably close to your 300 feet today. The currently configured LV transformers are in the basement. All of the LV landscaping wiring either goes to the outside and around to the furthest point of lighting (corners of the property) or goes through the basement and feeds one section of lighting directly in front of the house.

The newest zones now converted to LED do not exceed 50 watts of total power with the LEDs individually. I am guessing that the footprint of mentioned 50 watt transformer is not too large eh?

Are you switching on and off the LV LED landscaping lighting via the LV legs with the Insteon relay module?

 

[oberkc]

Are you switching on and off the LV LED landscaping lighting via the LV legs with the Insteon relay module?

No. I switch off power to the transformer. While insteon has devices that could be used to switch the LV zones, I opted for the simple, plug-in relay module, and plugged the transformer into this.

I actually have six "zones" of lighting, powered by the four transformers. Transformers are located at the four corners of the house, where wires exit through the foundation. One transformer powers three circuits, so this sounds similar to what you intend to do. One of the reasons I went with multiple transformers is to have different lighting scenes during different times of the year. I suppose you could do the same thing by switching the various LV "zones", but I chose the other route.

I would measure your current power consumption and size the power supply to have AMPLE extra capacity (double maybe?). I see little downside to this (maybe a slight loss of efficiency?). If you are like me, you are constantly fooling around with landscape lighting, adding and moving fixtures. The added capacity gives me comfort.

 

[pete_c]

Thank-you oberkc

I wired all of the LV zones to one area / corner in the basement exiting the foundation of the home there except for one front front of the house area where I have three LV wires going out to one small section . In one corner of the basement I put 4 commercial toroidal multi circuit / multivoltage transformers.

I've been going very slow until this year. I decided to change out the entire front of the home with LEDs. It is multizone multihomed LV cables so it was easy to do one zone at a time. While doing this though I started to change out many of the light fixtures that were over 6 years old.

I'm at a point now where I can measure the draw per zone. Do you have any suggestions for how to best measure a per zone draw of electricity?

Can I put a multimeter between the source voltage and destination voltage and get amperage draw; then figure out the watts from those numbers?

 

[oberkc]

Can I put a multimeter between the source voltage and destination voltage and get amperage draw; then figure out the watts from those numbers?

I have never done anything like this. I suppose, theoretically, this might be possible, but requires knowing the resistance of your wire. I am not sure that I would trust this method for accurate readings.

How easy is it to isolate the zones? Can you temporarily disconnect them? If there are few fixtures, you could simply remove lamps from individual zones and keep one zone wholly intact. Once isolated, I would use a killawatt meter.

 

[mdesmarais]

Can I put a multimeter between the source voltage and destination voltage and get amperage draw; then figure out the watts from those numbers?

Sure. You need to open the circuit to run the amperage measurement. (meter in series) Then close the circuit and check the voltage drop. (meter in parallel) If the loads are changing and causing ripple on the supply you may not get an accurate measurement unless your meter can average.

This will not take into account the losses of your AC/DC supply. Typically the larger the supply, the more passive loss it will have. I understand your discussions above about having headroom, but most supplies are most efficient when running at a particular load, near their max.

 

[oberkc]

Sure. You need to open the circuit to run the amperage measurement.

Good point. If one knows voltage drop and current, then one can calculate power. Power factor may come into play, if AC. One needs to know two of the following three: voltage, current, or resistance. I don't know how common it is to be able to measure current. I don't believe any of my meters can read current beyond the mA range, which would be too low for this measurement, I would guess.

but most supplies are most efficient when running at a particular load,

Thus my comment about the slight loss of efficiency. For my own edification, do you know how much efficiency penalty one pays for operating at 50% versus 90%? Does the type of power supply matter?

 

[pete_c]

My LV zones are set up such that they are easy to disconnect or switch off. I have labels set up and drawn a sort of map of what ons them and where they are located. Its not really an issue as I do not believe I will have any problems. I kind of over did the original LV set up with the multiple commercial transformers and wiring etc.

I'll just purchase a 50 12VDC transformer and start moving over to the conversion on the PS side of things.