What gauge wire for LED lighting?

Model Railroader Electronics and DCC
1

This is a question for those who know electricity.

I need to buy wire to connect my LED 12 volt layout lighting with the power supplies. Each connection will handle a maximum of 1.6 amps @ 12 volts over a maximum distance of 20 ft. The lighting strips will have a max. of 300 LEDs which are all 3528s. (1.6 amps is what the specs say).

Will 18 ga solid copper wire handle the load properly or do I need something heavier?

Thanks

Dave

2

Personally I think 18 is way overkill. For only an amp and a half you could run something closer to 26 and still be good. Check out the gauge/amp table here for more.

http://www.powerstream.com/Wire_Size.htm

It actually says you could get away with 27 but you could always do 26 just to be on the safe side.

Mike

3

No needed.

4

And that’s the thing. Even if the calculation holds up, 26 may easily cost as much or more than plain ol’ 22 gauge. And it never hurts to err on the side of a little extra capacity. It’ll also be a bit more snag resistant and easier to run being thicker.

5

I’ve run what seems like miles of ex-telephone wire (cause it was free) under my layout for LED signals and structures. I believe telephone wire is 24 gauge.

Mark.

6

I use 22awg black/red stranded auto rip cord, from All Electronics (or Mouser, I forget). Can be ordered to the length you like, was 11 cents per foot IIRC.

7

Mike (5150WS6)

Thanks for the wire chart. I saved it in my ‘favourites’.

Mike L, Rich, and Mark R:

Thanks for your quick responses.

To everyone, even though 18 ga. is way heavier than I need, I’m going to go with it because I can get it cheap ($51.00 Cdn. for 225 ft - 2 conductor with outer shield).

The 18 ga will also allow me to use crimped ring connectors in the power supplies.

Dave

8

Another way to get cheap wire is old CAT cables that you use for computers or network stuff. They have 5 or 6 wires in them that work pretty good for hobby stuff. And out of a 15’ CAT cable you can get a LOT of wire. We always have extra at work that have had the plug or something smashed.

9

Hi Paul:

I’ll have a look at what you suggested before I spend my money. I’m sure I will be able to find it here in Canada. Paying the exchange rate right now is dumb.

Thanks

Dave

10

I’m sorry … I believe I mis-read your opening post …

When you say layout lighting, are you referring to the lighting you are using to light your layout / room ? - or the LED lighting for your structures / signals ?

IF you are referring your to room lighting, I take back my post above - that refers to the LED lighting for structures, signals, etc… For LED light strips used to illuminate your layout / room - I too would go with no lighter than 18 gauge.

Mark.

11

Hi Mark:

Sorry, I could have worded my post better. We are talking about these guys which will be mounted on the ceiling for overall layout lighting:

http://www.ebay.ca/itm/200926217258?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Each strip will be about 16 ft long and will have 300 x 3528 white or blue LEDs. According to the specs. they draw 1.6 amps @ 12 volts max.

Structure and vehicle lighting will be a separate issue.

I thought some of the wire recommendations were a little on the light side.

Dave

12

Personally, I would run 18 ga lamp cord or 2 conductor thermostat wire. probably a little heavier then needed but easier to run and keep the job neat.

Martin Myers

13

Hi Martin:

The 18 ga. wire I am looking at is virtually the same as thermostat wire but it has an additional insulation sheath on the outside. The price difference is marginal and I like the idea of the solid wire being easier to keep straight vs the lamp cord. There will be quite a few wires coming off the ‘power wall’ and I want to keep things neat and tidy. The power wall will have 3 x 12 volt - 18 amp power supplies with 9 circuits each, although not all the circuits in each power supply will be in use.

Thanks for your input.

Dave

14

Dave,

There’s quite a few places on my layout where I have used wire duct or raceway to run multiple wires and keep everything neat (well, at least that was my original goal)

Here are some examples but you can search for others:

http://www.electriduct.com/Cable-Raceways.html

The stuff I used has snap on covers and some had notches already cut in and other was solid. Sometimes a commercial electrical contractor may have scraps of this stuff they may give you a deal on.

Some of the big-box stores sell stuff for concealing wire on walls for TVs and such that may work, too, but may be too small for the number of wires we model RR types need.

Ed

15

Hey Ed!

I was just looking at exactly what you are talking about.

I have mapped out my plan for the wall where the power supplies will be mounted. It will be on the outside of the layout room walls. There is enough space to allow me to simply staple the wires to the plywood backing sheet.

However, once things go through the wall into the layout room I want to keep them as organized as possible. That’s where I was considering the square conduit with the slots in the sides and a removable cap, like this:

http://www.digikey.ca/product-detail/en/3240189/277-5412-ND/2525017

I want to try to keep as much of the wiring as possible right behind the fascia. The track power buss will be mounted separately for obvious reasons, but I’m hoping to keep all the connections for things like the structure and vehicle lighting as close to the aisle as I can. I’m still trying to figure out exactly where the wires need to run.

Thanks.

Dave

16

Dave - Do you actually have those strips in hand ? Curious as to how bright they are. I tried a strip like that and it was no where near bright enough for MY room.

That strip you linked to has the 3528 size LEDs which produce about 7 lumens per LED with a total of 300 leds per 5M.

I found the 5050 size leds that produce about 12 lumens per led and had 600 leds per 5M lit my benchwork to the point I might seriously consider using them. Each led is almost twice as bright, with twice as many of them !

I also got to try a 5M strip that had a double row of the 5050 size that totalled 1200 leds per 5m … those were REALLY nice, but kind of pricey as well. Still mulling over that one.

Mark.

17

Hi Mark:

I have the strips on order. I haven’t received them yet.

I am very curious to see how much light they produce. I bought 5 of them but if they don’t work I’m not out much money. The were a little over $5.00 each with free shipping.

Worst case scenario as I see it is that I will have to buy the brighter LED strips and another power supply. That will still be way less than a decent new locomotive with sound.

Dave

18

Hi Mark:

After you asked the question regarding how bright the 3528 3000K warm white LEDs were I got to wondering if they would indeed be bright enough so I did a little more research. I have determined that they would not be quite bright enough so I have ordered 10 x 5 meter strips of 5630 Natural white LED strips with 60 LEDs per meter.

http://www.ebay.ca/itm/221604259638?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

The ‘white’ is brighter at about 4000 - 4500K vs 3000K for the warm white strips, and the larger LEDs will obviously put out a lot more light. I also have dimmers on order so I can control them as I wish.

I had to order two more power supplies but that was no big deal. I found a really good supplier in California - Mega Watt Power Supplies:

http://www.12voltpowersupplies.us/

John was really nice to deal with. Of course I haven’t had the opportunity to work with the power supplies yet, but at least i know they were made in North America and are not Chinese clones. I hope they are less likely to let the smoke out! That reminds me that I need to put smoke detectors in the train room and in the garage where the train room will be.

Dave

19

Now that I have increased the amperage for the 5 meter LED strips from 1.6 amps to 5 amps at 12 volts, what gauge wire should I use to connect them?

Mike 5159WS6 gave me a link to the American Wire Gauge chart but I am confused by whether my wiring would be classified as “chassis wiring” or “power transmission”. The two categories have hugely different amperage capabilities. Here’s the chart:

http://www.powerstream.com/Wire_Size.htm

Sorry to be so limited in my understanding of electricity.

Dave

20

Use the calculator at the bottom. Maximum amp capacity of the wire is the last thing to worry about. Voltage drop is the concern with long runs. It’s all proportional - a wire size that has less voltage drop will also have a greater maximum current capacity. Running wires along the fascia to power LED strips is not chassis wiring. The difference has to do witht he ability to dissipate heat. Inside a closed up box, there’s much less air movement compared to a wire in the open air.

The calculator at the bottom of the page will show the voltage drop for various sizes of wire based on the input voltage and the length. You’ll probably want #12 wire to run to an LED strip that draws 5 amps and even heavier wiring, or else locate the power supply closer to the strip, for runs much over 20 feet (one way). That keeps the voltage drop to under half a volt.

Unlike doing the same calculation for a DCC bus, where you might have the POTENTIAL to put a 5 amp load on the line, these LED strips WILL draw 5 amps, so using 5 amps in the voltage drop calculator makes sense here.

–Randy