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What gauge wire for LED lighting?

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Posted by Mark R. on Saturday, January 9, 2016 10:06 AM

I think what has been missing above is the fact we are talking about 12 volts, not 110/120 volts. This chart shows considerbly smaller values for 12 volt applications ....

Mark.

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Posted by Mark R. on Saturday, January 9, 2016 10:11 AM

To fine tune the lower current ratings, according to this chart, at 12 volts, you can push 5 amps through 22 gauge wire for almost 3 feet ....

Mark.

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Posted by rrinker on Saturday, January 9, 2016 1:08 PM

Mark R.

Can someone explain how the paper-thin circuit traces can carry 5 amps the length of the 16 foot strip, yet you have to connect it with 16 feet (for example) of wire 20 times plus that size to the power supply ?

Mark.

 

 I don;t know about your LED strips but the ones I have, that is no paper thin trace running the length of the reel, it's a pretty darn wide trace, actually. And relatively thick compared to a typical low voltage low power electronic PC board.

 There are two different things here - one is the current carrying capacity of a given size wire, which is the larger of the two numbers and represents how much current you can run through the wire without it heating up excessive. Then there is the voltage drop based on the wire resistence per foot and thus also directly proportional to the current. For a reasonable voltage drop of less than 1 volt, and with only 12V to start with, 1/2V is more reasonable, the amount of current that you can have will be much less than that size wire's absolute maximum current capacity.

 Per the chart - #18 wire is good for 5 amps at 25 feet. But draw 5 amps through 25 feet #18 wire and you will have almost a full volt less at the end. Not sure how they laid out that chart, if they mean 25 total feet for the circuit or 25 feet absolute distance. If they mean 25 feet for the circuit, that's only a distance of 12.5 feet. If they mean 25 feet actual distance, a complete circuit would comprise 50 total feet of wire, in which case the voltage drop is almost TWO full volts. The same length of #12 wire would drop .2 or .4 volt at 5 amps, depending on if they mean 25 total or 25 distance, with 50 feet of wire total. Significantly less voltage drop.

                           --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by Mark R. on Saturday, January 9, 2016 2:18 PM

Well, instead of guessing through online charts, I checked out a few online professional sites for LED ribbon lighting ....

Their recommendation for hook-up wire to be soldered to the strips is to use between 18 and 22 gauge stranded wire.

Don't shoot the messenger ....

Mark.

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Posted by rrinker on Saturday, January 9, 2016 2:42 PM

 Yes but for how long a wire run? The power supply and controller that came with the reel of LEDs I bought is only like #22 wire, but it's also only about 3 feet total.

                    --Randy


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Posted by Mark R. on Saturday, January 9, 2016 4:25 PM

rrinker

 Yes but for how long a wire run? The power supply and controller that came with the reel of LEDs I bought is only like #22 wire, but it's also only about 3 feet total.

                    --Randy

 

That would make sense based on the second chart I posted ....

Mark.

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Posted by rrinker on Saturday, January 9, 2016 5:08 PM

 Because I can guarantee that when I install LED strips on my layout, if I ever get to the point of building it, the wire runs from the power supplies to the strips will be #12 wire, like I use for my DCC bus, because they will be a lot longer than 3-5 feet. Like DCC boosters, the LED power supplies will be distributed along the layout to keep the wiring as short as possible. If sized for at least 2 strands, ideally it will be located in the center of the two strands, in order to get the most coverage possible. Assuming 5 meter reels - 5 meters in from one end is a power supply, then the second 5 meter reel, then another 5 meter real, thent he second power supply, etc.

>----------PS----------<>----------PS-----------<>----------PS---------<

Further complicated by two levels of benchwork and more than one strnad of LEDs, and some home bre controllers. In addition to white LEDs, I want a string of RGB ones to do dawn, dusk, and night effects. The ones I have are severely limited in the colors they display but until I dissect the controller I don't know if the limitation is in the way the controller was designed or in the IR remote that came with it which is the only way to control it. I need more steps per color to make the transistions smoother, plus I need to drive multiple spools. Not a terribly complex circuit, but for the number I need, it will have to work something like a DCC command station and boosters, where the main controller outputs a low level signal to multiple controllers, each running a reel or two of the LEDs so i don;t have to use massive heatsinks and fans to cool the controller. Multiple smaller, distributed controllers all keyed off one master signal. Should be fun to design and build.

                              --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by hon30critter on Saturday, January 9, 2016 6:30 PM

Hi Mark:

Yes, the subject was broached in another thread, but what I am asking is: is there any technical difference between speaker wire and other wire which would prevent its use.

As to the need for 12 gauge wire, there were several opinions offered but the PowerStream chart that Frank refers to seems to suggest that a continuous 5 amp load requires the heavy wire. I understand the apparent conflict between the trace wires used in the LED strips and the power supply wires but I want to get this right.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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Posted by hon30critter on Saturday, January 9, 2016 6:30 PM

Hi Frank.

Thanks. I already had the chart but maybe I'm not understanding it.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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Posted by hon30critter on Saturday, January 9, 2016 7:00 PM

I guess I should have added this question to the thread on wire gauge. I'll send Mr. Otte a note asking if he can combine the two.

There appears to be some conflicting information between the three charts referenced above. Based on a 20 foot run with 5 amps continuous draw @ 12 volts:

- The calculator in Frank's PowerStream chart suggests a minimum of 14 ga. to keep the voltage drop to about .5 volts.

- The first calculator that Mark shows suggests that 18 ga is sufficient, but it doesn't reference voltage drop.

- The second chart that Mark references suggests that 12 ga is required although you might get away with 14 ga if the actual run is only 18.4 ft.

 

Based on two out of three, my conclusion is that, in order to play it safe. I should work with 12 ga. wire. Many of the runs will be shorter than 20 ft. but I choose to use the same wire throughout.

As far as the original question about 'speaker wire', nobody has said it can't be used. I told you it was probably a dumb question!Smile, Wink & Grin

Thanks again

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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Posted by Bayfield Transfer Railway on Saturday, January 9, 2016 7:14 PM

1) Wire isn't THAT expensive.

2) Nobody ever said "Darn, my house burned down because the wire I used was too heavy."

 

 

Disclaimer:  This post may contain humor, sarcasm, and/or flatulence.

Michael Mornard

Bringing the North Woods to South Dakota!

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Posted by hon30critter on Saturday, January 9, 2016 7:22 PM

Michael:

You are right! Perhaps this is too much fuss over a simple problem, but I'm looking at running about 180' of feed wire for the LED strips. That's 10 x 5 meter strips on the ceiling and 2 x 5 meter strips in the staging. Working with lighter gauge wire would be nice but it's no big deal.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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Posted by Mark R. on Saturday, January 9, 2016 8:50 PM

I'm curious where the trade-off is .... you're running a total of 12 strips at 5 amps each for a total of 60 amps. Obviously this must equate fractionally to the amperage the power supply draws (?), otherwise you would need four dedicated breakers to hold it.

Most LED power supplies (like computer power supplies) are known as switching power supplies that utilize a much smaller transformer. Is there a co-relation to the step-down voltage that creates a step-up current ? Don't really understand the basics of a switching power supply myself .... Randy must know ....

Mark.

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Posted by rrinker on Saturday, January 9, 2016 9:18 PM

 Speaker wire should be fine. Sometimes it is rahter 'aggressively' rated and #12 speaker wire might not be a true #12. Something else to check is low voltage lighting wire - that is usually #12 and fairly heavy wire, used for pathway lights and so forth. Also known as landscape lighting wire.

 Mark - don't fall in to the same trap we covered back on one of the previous threads on critter's power requirements. When you drop voltage you raise current. That 60 amps is at 12 volts. That doesn't mean it needs 60 amps from the wall outlet - at 120V AC, it needs 1/10th the power, 6 amps - however no power supply is 100% efficient so it will be slightly higher. Say the power supply is 80% efficient, it would draw 7.5 amps from the wall outlet - well within limits of a 15 amp circuit.

                       --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by zstripe on Saturday, January 9, 2016 9:30 PM

Dave,

I am curious....Do You know Your electric service capacity of Your house? 100amp,150amp,200amp or even 250amp. I'm just wondering with all You plan on doing with lighting and layout...If You have the service capacity to accomplish that!

Year's ago, I had to up-grade My service and that included the power co. installing a larger cap. wire's from the pole to My service, I did the rest of the work, with help from My licensed electrician friend.....that included 50a 240v service in the ground for My compressor in garage, 40 amp arc welder, 40amp central air, 40amp dryer, along with the rest of the circuits in the house and I'm still at only 75% of the capacity. Using larger wire in My opinion is a plus...in the long run.

Take Care! Big Smile

Frank

BTW: Speaker wire....as long as it has the proper insulation,,,like heavy duty lamp cord wire. I use 14ga,speaker wire for My stereo system, which has a 250 watt amp and other goodies. But heavy gauge speaker wire,,,is not cheap!

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Posted by hon30critter on Saturday, January 9, 2016 9:42 PM

Hi Mark:

Here is how I think the setup will operate. Keep in mind that the 60 amps is at 12 volts:

- The supply circuit for the layout room is 20 amps @ 120 volts.

- Each of the LED strips draws 5 amps at 12 volts which, if I understand correctly, equals .5 amps @120 volts. Therefore, 12 LED strips will draw 6 amps @ 120 volts. The only other circuits that will be added to the 20 amp/120 volt circuit will be the outlets for the DCC system. Power for any power tools will be supplied by circuits that are already in place in the garage that are separate from the 20 amp/120 volt layout supply.

- The Led strips will be powered by three power supplies. Each power supply is rated at 36 amps @ 12 volts. Two of the power supplies will run 5 LED strips each which is a total of 25 amps each so they will not be anywhere near their maximum output. The third will run the remaining two 5 meter strips plus the structure lighting and the tortoises which will probably amount to less than half the power supply's capacity.

- Each of the 12 LED strips will be fed through a fuse block with an individual 7.5 amp automotive style fuse per 5 meter strip.

- The maximum length for the runs to the LED strips from the power supplies will be about 20 feet. Most will be less, but I'm going with 12 ga wire regardless of how much overkill that is.

Just for safety's sake, I will ask an electrician to approve the whole thing before turning on the power.

Comments please.

Thanks

Dave 

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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Posted by hon30critter on Saturday, January 9, 2016 9:53 PM

Hi Frank:

To answer your question, the house has a 100 amp fuse panel. That is at 120 volts. The power for the LED strips is at 12 volts, which is what is confusing the whole issue. 60 amps at 12 volts equals 6 amps at 120 volts so the load on my house supply will be peanuts.

If I have that wrong, somebody please tell me before I light up the whole neighbourhood!Smile, Wink & GrinLaughLaugh

I do appreciate your concern.

By the way, the price of speaker wire  isn't that far off the price of 12/2 house wiring so I'm still undecided as to which I will use. There are pluses and minuses to both. Speaker wire brings the risk of stray strands but is easier to pull.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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Posted by rrinker on Saturday, January 9, 2016 11:09 PM

 Sounds all fine, using 25 out of 36 amps leavea s nice safety margin on the power supplies. Switching power supplies are strange beasts - they are usually most efficient from 50-80% load, so you don't want to run them too lightly loaded, nor do you want to load them right to the limit. Light load doesn't  hurt anything, it just means it uses more power relative to the output - say 75% efficient instead of 85% efficient at 80% load.

 100 amp service to the house is pretty light these days - I take it you don't have too many electrical appliances like water heater, AC, stove, or clothes dryer. Most newer houses are all 200 amp minimum - and I don;t have much in terms of high power electrical appliances, just my central AC and pool pump. Stove, heat, water heater, and clothes dryer are all gas.

                     --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by hon30critter on Saturday, January 9, 2016 11:47 PM

Hi Randy:

Yes, 100 amp service to the house is not exactly up to modern standards, but we seem to do fine. The house is 38 years old. I had the panel replaced a couple of years ago when we put in a hot tub and even though the hot tub circuit itself is capable of handling 50 amps it won't unless we run all three pumps at high speed which we never do. In fact we rarely run the pumps at all beyond what is needed for heating and filtration purposes. We do have an electric stove, AC and dryer. The water heater is gas. The whole system passed inspection so I have to assume that things are OK.

More to the subject, the electrician installed the 20 amp circuit for the model railroad when the new panel was installed, and he said it would be no problem to run a second one if needed, which it won't be.

So, however the electrical gods work, we seem to be fine.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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Speaker wire for LED strip lighting?
Posted by hon30critter on Sunday, January 10, 2016 1:18 PM

Hi guys (and girls):

This is probably a dumb question, but here goes.

It has been suggested that I use 12 ga. wire for connecting my LED strip lighting. The lighting draws 5 amps at 12 volts for every 5 meters, hence the heavy duty wire.

Can I use 12 ga speaker wire?

Thanks

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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Posted by rrinker on Sunday, January 10, 2016 1:18 PM

 Wow, your house is newer than mine, and I have 200 amp service - it doesn't look like it was replaced and upgraded, but when the house was built it didn't even have AC, or the pool. It did have electric stove and oven which I replaced with gas. There is an outlet for an electric dryer, but the one that was here is gas. I'm sure you're OK, especially if an electrician has looked at it. My Mom's house was built in the 50's and only has 100 ampo service, and outside of oil heat, it's all electric. Never had a problem expanding the top bedroom (mine) and running several window air conditioners and all my computer equipment plus small train layouts (4x8 max). It all works because you never actually tuen on everything all at the same time. If you turned on all the lights in your house, had the hot tub going, were baking a cake, drying a load of clothes, and it was the middle of August so you had the AC cranked up you might end up drawing enough to trip the main breaker. But we tend to not do things like that, which is how it all works - during normal everyday life you won't max out that input.

                       --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by Steven Otte on Monday, January 11, 2016 8:52 AM

Threads have been combined at the OP's request.

--
Steven Otte, Model Railroader associate editor
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Posted by mfm37 on Monday, January 11, 2016 4:50 PM

Simplest way to find the capacity of a circuit is to convert to Watts. 60 amps at 12 volts is 720 watts. A 120 volt circuit with a 20 amp breaker will handle 2400 watts. Using 80% of the circuit's capacity for safety you get 1920 watts. Plenty to handle those led light strips and still run the trains.

Martin Myers

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Posted by hon30critter on Monday, January 11, 2016 6:13 PM

Thanks Martin:

I had used the conversion to watts to come to the same conclusion so I'm glad to see I had the numbers correct.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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