Thank you, my education continues.It isn't quite as simple as 100W. It's really 100VA, but can also be as low as 60VA if you are using 12V drivers. Class 2 requires that a transformer or power supply inherently limit its output to 100VA (or less). This is to keep the current low enough to reduce the risk of fire in case of a short or other failure.
That said, there are some Class 2 drivers that are over 100VA, but achieve this by have multiple outputs, each limited to 100VA. So you would still need to have more than one 24V power feed from the driver to your LED strips. That will also help reduce the current in feed, further reducing voltage drop.
When choosing a power supply or driver, don't confuse a Class 2 rating with IEC Class II. IEC Class II governs the construction and insulation of the power supply and protecting users from the risk of shock, and has nothing to do with limiting the power output.
In addition to a Class 2 driver, you need to use wire/cable that is also rated CL2 or better.
With Class 2 wiring, the rules are more relaxed, allowing you to make splices and connections without them being inside an approved junction box. Wires can be smaller; 18AWG and smaller can be used.
If you go with Class 1, then the rules are as if you were wiring a 120V circuit. Junction boxes required, wires no smaller than 16AWG, properly protected using conduit, or NM-B cables.
In theory, you could connect more than one single output driver to a single dimmer. BUT, there could be some potential problems. One is that for a particular setting of the dimmer, the two drivers might choose slightly different dimming levels (such as 60% on one and 50% on the other), and that could be noticeable. It might require fiddling with the dimmer setting to get them both to the same level.
For example, if say 18 gauge wire used in system and amounts to 30 feet, is that the footage used for the driver maximum plus 10%?In theory, you could connect more than one single output driver to a single dimmer. BUT, there could be some potential problems. One is that for a particular setting of the dimmer, the two drivers might choose slightly different dimming levels (such as 60% on one and 50% on the other), and that could be noticeable. It might require fiddling with the dimmer setting to get them both to the same level.
The other possible problem is inrush current when you first turn on the lights. The drivers have pretty high inrush currents, and two of them kicking in at the same time might exceed the specs of what the dimmer can handle. For example, the Zurik 200W driver has an inrush current of 15A, which should be ok. But two 60W drivers have 28A (14A + 14A) of inrush current, which could blow the dimmer. So for this to work, you would need a dimmer that can handle the much higher current load.
Your photo of the driver doesn't have enough resolution to read the output specs, but from the pigtails, it does appear to have 4 outputs (2 in each cable).
The advantage of using a multi-output driver is that it should set the dimming level on all outputs to the same level.
Zurik does make a 192W multi-output model, similar to the 200W single output model you originally mentioned. That would appear to fit your needs. Still, check with the folks at Flexfire to see if they agree. This driver has an inrush current of 19A, so be sure to choose a dimmer that can handle the load.
**I sent a better photoSince you will have a driver with two separate outputs, each output must drive separate sets of LED strips, with no connection between them. You can't common the two outputs together.
Calculating voltage drop gets a little complicated in layouts like this because one 4' wire segment carries just the current from say a single LED strip, but then the next upstream segment back to the driver carries current from two or more segments. So you need to calculate the voltage drop for each segment and add those numbers for a each full path back to the driver together to figure the actual voltage drop a strip will see.
The voltage drop along the length of the actual LED strip matters, but as long as the last LED at the far end of the strip gets enough voltage, it will be fine. Since we don't know the gauge of the conductors on the LED strip, we can't easily calculate what the drop would be. So all we can do is worry about providing enough voltage at the connection point to the strip and make sure it is within the manufacturers specs.
Your picture of the wire layout got cropped a bit, and I can't see the length of the strip all the way on the left. But adding up the other lengths, I'm guessing it might be a long one of about 15', since you say you will have 30' of LED strips.
You show one 4' drop feeding two LED strips. It's ok to do it that way, but you will need a splice there under the cabinet to branch out left and right to the two strips. Consider how you want to make the splice and hide it or protect it from damage. Another option would be to make 2 drops, one for each strip, and make the splice up at the top of the cabinets where it will be more out of the way.
One easy way to make the splices is with Dolphin Connectors (aka "B" Connectors). They are pretty compact, and you can splice up to 3 20 gauge wires in one connector. You need to use proper crimping pliers in order to make a solid connection. They are made to connect right through the insulation without stripping, but for beginners, it is often better to strip and twist the wires and then crimp them in the connector. No extra insulation is needed.
Here are two different ways you could lay out the wiring. The longest run on the left, at 22', would have a voltage drop of just under a volt powering a full 15' LED strip using 20 AWG wire. I didn't calculate the voltage drop for the other driver output, but since it is shorter than 18' and doesn't carry the current of all the segments along the entire length, it will be less.
The bottom layout would have the lowest voltage drop, since every segment has its own run back to the driver, and no segment is carrying power for more than one segment. It's probably overkill.
If you want to conceal the wiring within the cabinets, you could use some plastic Wiremold.
View attachment 679337
Ok, I'm confused. Originally you said that there would be 2 runs of 16'. I took that to mean two 16' strips of LEDs. Now you are saying there is approx 30' of load. Is that the total length of the LED strips, or are you including wire lengths in that? Makes a big difference. Although wire has some resistance and that consumes a bit of power, it is usually not considered part of the load.Thanks.
There is approx 30’ of load. The 5 LED strips are approx a total of 14’. I thought by T’ing off on 2 of the LED’s, it would lessen the load by 8’, but maybe that s not necessary.
An electrician friend suggested using a 12V 75W dimmable driver. He also said I could use 14/2 wire. I’d rather use 16g or 18g wire as it would be much easier to hide.
The LED strips that Fireflex recommended use 3.5W per foot.
I’m right probably making this harder than need be, but I try to do the best just possible.
You are very kind to take this interest.
Sorry, I’m confusing the situation.Ok, I'm confused. Originally you said that there would be 2 runs of 16'. I took that to mean two 16' strips of LEDs. Now you are saying there is approx 30' of load. Is that the total length of the LED strips, or are you including wire lengths in that? Makes a big difference. Although wire has some resistance and that consumes a bit of power, it is usually not considered part of the load.
I don't see an updated photo. What is the length of the LED strip all the way on the left side?Sorry, I’m confusing the situation.
Yes, I started out with 2, 16’ runs but have changed to the one contiguous run.
Instead of explaining it, maybe look at the non cropped photo I just sent.
The 2nd layout you sent is close to the that photo.
Ok, based on the updated diagram, you have 160" or 13.3' of LED strips. At 3.5W per foot, that's a total of 46.7W.
Thank you for your time and it would have been less work and frustration for you, if I had just included a layout and dimensions and you could have gone from that without me muddying the waters.Ok, based on the updated diagram, you have 160" or 13.3' of LED strips. At 3.5W per foot, that's a total of 46.7W.
I think you would be fine with a 60W, 24V single output driver.
Here's a diagram similar to yours with voltage drop calculations. I made up some numbers for the various horizontal wire segment lengths based on the photos of your kitchen. Not sure how close to your actual lengths they might be, but it's simple enough to recalculate things.
[Edit: I got side tracked during my original calculations and forgot that you were using a 24V supply. I've corrected the numbers below to reflect this.]
As I said earlier, the worst drop will be at the 44" segment. I estimate the voltage there will be 23.65V. I don't think you will have any problems due to voltage drop with this layout.
If you really want to be sure before installing everything, do a simple bench test and wire up the full 15' reel of LEDs to the driver using a 22' section of 20 AWG cable and power it up. If that works to your satisfaction, this configuration will also work.
View attachment 679391
Although it is ok to run the wires in the attic, it's best not to place the driver there. The hot attic temperatures will shorten the life of the electronics.If you were to do this from scratch, how would you do it? Layout, driver specs, etc?
I can install the driver anywhere that would be more efficient, just want to have the safest and most professional installation possible. Originally, I was going to T off in the attic but got approval from the boss to run the wire in the upper cabinets, reducing the length from 4' to 3' on three of the drops. Also, I corrected the distance from drop to drop.
Thank you very much!Although it is ok to run the wires in the attic, it's best not to place the driver there. The hot attic temperatures will shorten the life of the electronics.
My first consideration for the layout is driven by what's practical in terms of where to place the driver and how to run the wires. It needs to connect to AC power, so where can it be placed that allows that? If it can be placed somewhere in the middle of the LED strips, then that allows you to run two sets of backbone cables, reducing the length of each - one to the left and one to the right. Even with a single output driver, that will split the load across the two cables and reduce the voltage drop on each one. You've take that approach by having a direct connection to the driver from the rightmost LED strip. A 50/50 split of the load would be nice, but in your case, the load on the backbone is low enough that it still works out.
Sometimes, you may have no choice but to place the driver at one end. Then you are faced with passing the current for all the strips through one backbone cable, which may force you to use a heavier gauge cable. The other choice would be to run multiple cables. In my original pair of drawings, that was what I tried to show with the bottom drawing. You don't necessarily need to run a separate cable for each LED strip. How many strips you can connect to a cable will depend on the length/load of the strip(s) and the voltage drop it creates.
I prefer to use smaller gauge cables if possible. They are easier to conceal, and with 20 AWG, you can use the solderless connectors. I prefer solid wire rather than stranded, as it will keep its shape better when you need to bend it. Just don't bend it in one spot too often!
To calculate the voltage drop, you need to know the wattage and current that each strip requires. At 3.5W per foot, that's 0.292W per inch.
44" strip: 0.292 x 44 = 12.8W
12.8W / 24V = 0.53 A
Do that same set of calculations for each strip.
The next step is to calculate the voltage drop for each wire segment. Start with the segments that feed each strip.
10' of wire x 2 (the current has to travel down and back) = 20'
20 AWG has a resistance of 10.15 Ohms per 1000 feet. So 20' of wire is 0.203 Ohms.
The voltage drop is current x resistance (IxR), so 0.53 x 0.203 = 0.1076V
As you move upstream to the driver, the backbone segments will be carrying current for more than one LED strip, and you need to add the current values for each strip together when calculating the drop for that segment.
Finally, to calculate the total voltage drop that is present at a LED strip, add up all the drops for each segment in the path between the strip and the driver.
For the 44" strip, that's 0.1076 + 0.0853 + 0.1839 = 0.38V. 24 - 0.38 = 23.62V at the strip.
At 23.62V, you're only 1.6% below the nominal 24V requirement, which is a good place to be.
Here's an updated set of calculations based on your wire lengths. Overall, things didn't change much - just a few hundredths of a volt.
View attachment 679456