Loads

[aLf]

I'm adding a Low Voltage (magnetic) transformer for outdoor lighting. 110v to 12v. It is rated at 500w. The InlineLinc I ordered says 480w Max-15a. Question is that it is not an incandescent load, is it limited to the watts or amps? My layout calls for 400 watts worth of 25 watt bulbs. I'd like to expand the layout in time, but do not want to go over the 480 limit on the Inline. Does anyone have a good rule of thumb on this?

 

Thanks,

 

aLf

[Sub-Routine]

Hi aLf,

 

You have to consider the load plus some loss in the transformer. You should be fine with 400W of load.

 

Rand

[apostolakisl]

Your safest bet would be to hook up the lighting system minus the insteon unit and use the kill-a-watt or similar to measure the actual consumption. If it is under 480 watt then you should be good.

[IndyMike]

Hello Alf,

 

Sorry I'm a bit slow on the reply...

 

Since your outdoor lighting will be powered through the transformer the load will appear inductive to the InlineLinc. SH rates the InlineLinc at 15A inductive.

 

The incandescent rating on the Inlinelinc is due to inrush current that occurs when an incandescent lamp is first turned on. This inrush can be 10X the normal current for the bulb. For a 500W incandescent this would be on the order of 42 amps.

 

On the flip side, transformers also demand inrush current when first switched on. The amount of current demanded is far less predictable (depends on the transformer type, where the AC signal is at turn on, and residual magnetism in the core) and can actually exceed that of an incandescent bulb. The fact that SH rates the relay contacts of the Inlinelinc at 15A implies that they are either using compensation or consider the likelihood (rate of occurrence) of a max inrush as small. Edit - this is incorrect. The website information is misleading. The label on the back of the relay devices (V2.5 Switchlinc) specified 480W Incandescent and Inductive.

So much for the long hair stuff - I was browsing some sites the other day and came across an interesting guide for planning outdoor lighting. Most of my outdoor lighting is far lower power than what you're planning. At 500 watts, you'll need to plan your system to avoid voltage losses over the length of the run. The manufacturer suggests using 3 - wire cable and staggering the lamps across the phases to cut down on voltage losses and cable runs. It was something I hadn't thought of before (maybe it's standard). The article is located here: http://www.ruudlightingdirect.com/landscape/5_step.asp

 

The specific circuit diagram is here: http://www.ruudlightingdirect.com/landscape/dualcircuit.html

[aLf]

Indy:

 

Thanks. As always you have the "deep" answer. I have another transformer running the first edition of the system. It has worked well for a number of years. I will look at the amp draw for the new system and be sure it falls into that criteria. When shopping for the new fixtures (Kichler), I noted that almost everything I have is now outdated and being discontinued where they are switching over to LED's. One fixture that was 24.4 w, is now 4 w. At that rate, a guy could just about do the whole thing in a 500 w transformer. So wrapping this up, I assume that according to your info, as klong as the amps are less than 15 the SWL is OK? In this case Watts divided by 12 Volts = Amps?

 

aLf

[oberkc]

When shopping for the new fixtures (Kichler), I noted that almost everything I have is now outdated and being discontinued where they are switching over to LED's.

 

I did not want to jump in here, but wanted to throw my support for the LED approach. I have re-lamped all my fixtures with LEDs, and am very satisfied. I have four switching power supplies, controlled by four appliance modules. All power supplies are mounted inside, with LV wire exiting the house through conduit. Total power is less than 50 watts for about 40 fixtures.

 

Voltage drop is not much a consideration at these levels. I have runs over 200 feet. I have negligible (none so far) bulb failures. I highly recommend this approach.

[aLf]

Oberkc:

 

Is there a source that I could look at to find what I need to convert everything over? What about the transformer. Do you need to do anything to it when you lessen the load? I'm all over converting. I just don't want to do it twice. I'm a sponge with info, so feel free to soak me with sources for the change-over.

 

Thanks,

 

aLf

[IndyMike]

Alf,

 

Yes, as long as the current draw is below 15A you should be OK.

 

The 500W / 12V = Output current. You are looking for the input current to the transformer.

 

As Rand indicated, the transformer isn't 100% efficient. Most run above 90% efficiency, but some are designed to be less efficient to protect themselves from output shorts.

 

To be safe, use 80% efficiency - 500W/.8 = 625 W input power

 

Input Current = 625W/120V = 5.2 Amps (plenty of margin). Incorrect

Edit: Just looked at the back of an old Switchlinc Relay unit - The label stipulates 13A resistive/480W Incandescent and Inductive. This is the only place I've ever seen an Inductive rating for a relay unit. The website ratings for the relay units are "non-specific and misleading" in regard to Inductive loads. While I believe that a 480W rating is conservative for an inductive load, it is what SH has certified the device to. Please disregard my earlier comments regarding a 15A rating for inductive loads.

[IndyMike]

Oberkc makes an excellent point.

 

I'm not sure how much the Led lamps cost, but the price would be offset by the lower cost of a smaller transformer and lighter gauge wire.

 

The 500/600W transformers I saw were above $200. Wire gauge for any appreciable run length would be 8 or 10Awg - ain't cheap. That's without mentioning electric bills.

[apostolakisl]

I think it will depend mostly on the style plug your current fixtures require. LED's are polarity specific DC, not AC. Since I assume you are running a 12v AC transformer you will need LEDs that correct for that and fit into your fixture sockets.

[aLf]

Has anyone done this kind of transformation (inc. to LED)? Where would I start looking for appropriate bulbs?

 

These are the transformers I use. They are bullet proof. This company makes some really cool back lighting, mainly steps, etc. 500W ran me a bit over $200.

 

http://www.robertssteplite.com/

http://www.robertssteplite.com/Websites/RSL/Files/Content/35040/Transformer%2012v%201-09.pdf

 

aLf

[apostolakisl]

I can tell you where they don't have them. Lowe's. I was just there an hour ago and asked.

 

I have never seen LED's that would work in the confined, poorly ventilated , outdoor exposure type fixture, except for the solar ones which in my mind pretty much stink.

 

I would be very interested to find out if someone else has non-solar outdoor LED fixtures and how it all works (replacement bulbs versus needing entire new fixtures).

[oberkc]

Is there a source that I could look at to find what I need to convert everything over? What about the transformer. Do you need to do anything to it when you lessen the load? I'm all over converting. I just don't want to do it twice. I'm a sponge with info, so feel free to soak me with sources for the change-over.

 

Most of my fixtures are those commonly available at the normal places. I tend to look for the aluminum or copper ones. Plastic has simply not held up for me. They use either wedge base or bi-pin lamps.

 

Regarding lamps, I have used exclusively:

 

http://www.superbrightleds.com/led_prods.htm.

 

All lamps that I use came from here. Also, my four power supplies came from this outlet. I am a happy customer of this company.

 

Be sure to pay attention to light color. I prefer mostly the "warm" whites. find the lamp with the correct base to fit your fixtures. Try a couple to see how you like them, find your favorites, then do your entire landscape.

 

Based on guidance from this company, I understand that LED lamps work better on a regulated power supply. Many of the standard landscape lighting transformers may send to high a voltage, due to the low power consumption of LEDs. So far, this has worked for me.

[apostolakisl]

Have you bought any of their other lights? I am interested in the spots for my china cabinet. The incandescent ones cost like $5 a piece and only last about 6 months at most. I am getting very anoyed at having to keep replace them. I was looking at these E27-xW4 White LED bulb. The color I was thinking might be best is natural white for the crystal to shine.

[jerlands]

Regarding lamps, I have used exclusively:

 

http://www.superbrightleds.com/led_prods.htm.'>http://www.superbrightleds.com/led_prods.htm.

 

All lamps that I use came from here. Also, my four power supplies came from this outlet. I am a happy customer of this company.

 

 

I love the low wattage LED's offer and in certain apps they're great. I purchased 6 of the "Model E12-W32 Candelabra Base bulb" from http://www.superbrightleds.com at $20 a pop and am not a happy camper. These particular LED's are nowhere near as bright as the advertised 15-20W comparison but more like a 7 watt incandescent. Also, one arrived with the foot only partial and wouldn't make contact and 2 failed within 4 months. I did however purchase an inexpensive spot and rope LED from Home Depot and these work great in my china and display cases. I'm of the opinion screw base LED's are not yet ready for prime time.

[oberkc]

Have you bought any of their other lights?

 

I have purchased many lamps from superbrightLED. All of my purchases, however, were for 12V bulbs for use in my landscape fixtures and for my car. As said by apostolakisl, one must be selective. The output claims about some LEDs are overstated. Another factor about LEDs that I have seen it in the beam patterns. Incadescents, by nature, tend to send light in all directions. LEDs are typically designed in such a way as to as to concentrate their output in a more limited direction.

 

Like apostolakisl, I have purchased (from other sources such as sam's club, Lowes, Home Depot) replacement bulbs with medium edison base and candelabra base. I have fount that most of these are not good replacements in all uses. Most of their light is concentrated straight "up" (away from base). This tends to limit the useful applications.

 

In general, I like from superbrightLED those that have the "SMD" high power LEDs, such as:

 

http://www.superbrightleds.com/cgi-bin/ ... tm%23OTHER

 

http://www.superbrightleds.com/cgi-bin/ ... m%23MALIBU

 

http://www.superbrightleds.com/cgi-bin/ ... m%23MALIBU

 

http://www.superbrightleds.com/cgi-bin/ ... x48SMD.htm

 

I like them all in warm white. This is somewhere between incadescent and hologen, by my eye.

 

Have you bought any of their other lights? I am interested in the spots for my china cabinet. The incandescent ones cost like $5 a piece and only last about 6 months at most. I am getting very anoyed at having to keep replace them. I was looking at these E27-xW4 White LED bulb. The color I was thinking might be best is natural white for the crystal to shine.

Regarding cabinet lighting,

 

Besides those for landscape and car, I have not purchased any others. However, the MR-16s I use for landscaping would work anywhere else that requires MR-16 (12 volts). In my estimation, the warm white might be too yellow for your application, and the cool white too blue. The color of halogen (4000K?) would be ideal. For some reason, I could not identify the E27-xW4 from their web page. My only suggestion is to pay attention to color (look for about 4000K +/-500) and beam pattern/spread. If this is an edison medium base, check out sam's club. They had a screw-in spot bulb that I have tried and currently use. It is close to halogen in color and a pretty narrow beam that might work well in highlighting your cabinet.

[aLf]

Hey IndyMike &Guru's!

 

Maybe a dumb question and should remember from my airplane mechanic's days.

 

I know Watts=Volts X Amps, but here is my dumb. (I read your post Indy and am a bit confused as to the Wattage calc's. I'm not quite sure how the input/output Wattage works.

 

I am installing a low voltage transformer ( 500 Watt, 12 Volt output) to run some landscape stuff. It will be controlled from a SWL. I "think" the SWL is OK for 500W and 13 Amps (chime in if not). The transformer has two circuits built in that are capable of carrying half each. My total load (in planning) is about 300 Watts worth of lights. Do I figure the load off 12 Volt or the 110 input? Obviously will make a big difference in Wattage.

 

Thanks,

 

aLf

[Brian H]

300 Watts on the output is 12 volts 25 amps 12V X 25A=300W

Since the transformer is not 100% efficient. The 120 volt primary will draw more than 300 watts.

 

Now my math maybe rusty here. I believe at an efficiency of 80%. The AC 120 volt side would be drawing 375 watts or 120V X 3.125 A.

If the transformer was a impossible 100% it would be 120V X 2.5 A =300 W.

[aLf]

Hey Brian:

 

So let me get this.

 

The wattage is the same on both sides (a perfect world 100% efficient), if I had 300Watts on the LV side would equal 300Watts on the 110 side? That said, just figure the inneficency (80% would equal 375Watts). Then take the old therory of W=V*A ( 375/110=3.4Amps) or there abouts. The SWL takes 13-15 Amps, so it's good to go? If this is right, my 1,000 Watt (fist transformer is drawing 11 amps on another SWL?

 

I'm still unsure why there is a difference between inductive and a load like a light bulb? I assume a modern transformer (magnetic) is an iductive load.

 

Thanks for the info.

 

aLf

[Brian H]

Yes the light bulb is resistive and the voltage and current are in phase with each other.

 

Inductive and the current lags the voltage by 90 degrees in a perfect world.

 

If the supply is a transformer and not one of those new electronic ones. I would expect it to be an Inductive load.

 

This current lagging the voltage maybe why some modules have a different rating for inductive loads. I didn't see one for the SWL or just plain missed it.

[jerlands]

300 Watts on the output is 12 volts 25 amps 12V X 25A=300W

Since the transformer is not 100% efficient. The 120 volt primary will draw more than 300 watts.

 

Now my math maybe rusty here. I believe at an efficiency of 80%. The AC 120 volt side would be drawing 375 watts or 120V X 3.125 A.

If the transformer was a impossible 100% it would be 120V X 2.5 A =300 W.

 

I'm not certain, and of course it would depend on the type and manufacturer but I think transformers are fairly efficient, something like 98+% for a large single phase supplying a home. Smaller magnetic transformers perform similarly but not quite.

 

Jon

[aLf]

The transformer manufacture shows the 500W as a Max 400W output, I would assume from that without seeing printed specs that equates to 80% or else it is legal CYA.

 

aLf

[Brian H]

Sounds like they did the math for you.

When fully loaded 500 watts on the AC Input with 400 watts for the 12 volt lights on the load side.

[aLf]

Hey Guys!

 

I decided that the best way to skin this cat is to just link the new In-Line Linc with the original SWL that controls the first transformer. Due to load exceedence on the first SWL circuit in the house, I have to run another new circuit to the new In-Line Linc (which controls only the new transformer). I have two options, 1) just link the two. 2) Make a program in ISY that turns the In-Line Linc on when the SWL goes on. There are benefits to both ways. Option 1 will just work, but in winter when the transformer is not used will still turn on when the SWL goes on (SWL does have winter use, In-Line Linc only runs in summer). Option 2 can be setup for the winter/summer schedule. I have security concerns with all Insteon and have everything turned off hourly when I'm not home. What do you guys think is the best way to handle this. Keep in mind that any time SWL is on, I want In-Line Linc on as well, just not in winter nad never should come on when my "AWAY" or (all off) is running.

 

Thanks,

 

aLf

[IndyMike]

Hello Alf,

 

I apologize, but I have to retract my earlier posts indicating that the relay units were rated for 15A inductive loads. This was a bad assumption based on the website information.

 

Today I found an old photo that I had taken of a V2.5 relay unit. Based on the label, the inductive rating is the same as the incandescent.