Wiring a power bus for structure lighting

[jacon12]

In the coming weeks I'll be running a bus(s?) beneath my layout to power the lights in various structures.  It will be approx. 40 to 50 feet long and I plan to power it with an older DC power pack, but I have questions... namely

1-  what guage wire should I use for this main.?

2- stranded or solid?

3-  will my old MRC dc power pak be sufficient?

Any other tips/suggestions are appreciated.

Thanks,

Jarrell

[slickfg]

 Jarrell,

 For your main bus lines I would recommend that you use at least #14 stranded wire. Stranded wire is more forgiving to being bent and twisted than solid wire, also not nearly as frustrating to work with. Installing terminal strips at regular points along you layout to connect your structures to. By adding terminal strips will help keep your wiring neat and makes trouble shooting easier. I would also recommend (due to past headaches) that you keep your track wires to one set of colors and your accessories to another set of colors. (ie. track power - red and black, accessories green and yellow)

Another tip with stranded wire is that when using terminals - 1. Tighten the wire under the lug 2. wiggle the wire a few times (this will help the wires to settle if you want to call it) 3. Retighten the lug. You will find that it will not be as tight as when you first tightened it. Now you will have a good connection that shoud give you trouble free service for years to come.

 As far as your MRC power pack it should do the trick

 Hope it helps

Jonathan

[ewl01]

I'm sure you already have one. A terminal crimper for putting solderless connectors at those terminal strips.  Makes life a lot easier and eliminates the possiblity of a stray strand touching something you don't want it to.

[jacon12]

 Those are some great tips, Jonathan.. I really appreciate it.  I hadn't even thought of the terminal strips but that would help to simplify things greatly and besides that it makes perfect sense!  Thanks for the tip on wire/lug tightening too!

Jarrell

[MisterBeasley]

For any bus, the thicker the wire, the better off you'll be.

I also like the idea of using terminal strips, particularly the kind with screw terminals.  They allow you to easily remove the structure for maintenance, if necessary.  If possible, though, mount the lighting on the layout, not the structure.  I know, in many cases that's not possible, but it's a lot easier to just lift the building off its foundations if the wires aren't attached to it.

I use 16-volt bulbs for all of my structure lighting.  By standardizing on one voltage rating, I only need one power supply for the whole thing, assuming it's got enough capacity.  I run the lights at 10 volts, which greatly extends their life.  I don't need the brightness associated with running them at 16 volts.

[tstage]

Jarrell,

I'm in the process of also trying to think this through myself so I look forward to the responses that others will be offering you.  Here are a few thoughts of my own:

• Your old MRC power pack should work just fine in this capacity.  This has the advantage of allowing you the ability to "turn down" the voltage to your bulbs; thereby increasing their overall life expectancy (hrs rating) significantly.
• Do you want to be able to turn individual lighting (e.g. interior rooms in houses) on and off?  I do so I plan on having at least two separate lighting buses: One for exterior lighting; one for interior lighting.  I also prefer to wire my lighting "in parallel" rather than "in series".  Wiring "in parallel" allows you the option of controlling an individual light (or groups of lights) separately.  Course, this complicates wiring more than it does if you just wire "in series".  However, it does have the advantage of easily detecting which bulbs have burned out and individually switching them out without bringing down the remaining bulbs in the string.  Using terminal strips in this capacity will make troubleshooting and bulb replacement a lot easier, too.
  
• What size/type bulbs will you be using for your lighting?  I definitely like LEDs for locomotive headlights but prefer incandescents for everything else.  Incandescent lighting gives off a warmer, more diffuse glow than LEDs, which tend to be very focused and too directional for my taste.  Also, as mentioned in Point 1, incandescents are adjustable and can be dimmed for more subtle lighting effects with your power pack.
  
• I'm not an electrical guru on this topic but the bus size would be contingent on the type/quantity of bulbs you use for lighting.  Incandescents come in a variety of sizes, voltages and amperages.  Miniatronics sells 0.7, 1.2, 1.7, and 2.4mm diameter bulbs (plus a few larger sizes) and they mostly come in either 1.5V or 12V, with a few other voltages thrown in.  The most common amperages are usually 15, 30, and 40 mA.  Generally, the larger the bulb diameter and voltage, the more hours it's rated at.  So, you would need to determine how many bulbs you plan on using on your bus and what their accumulative mAs add up to to figure out which bus wire gauge would be correct in your application.  Anyone with more electrical knowhow than myself is more than welcome to refute this.  Ballpark speaking: Although bigger can't hurt - especially with longer runs of wire, 16 or 18ga wire should be more than ample for a lighting bus.
• As far as the type of wiring, like a DCC power bus: Stranded or solid shouldn't really make any difference.  It's your choice.

Okay, Jarrell, I've pontificated my ignorance enough.  I hope some of this has been helpful.

Tom

[howmus]

jacon12

In the coming weeks I'll be running a bus(s?) beneath my layout to power the lights in various structures.  It will be approx. 40 to 50 feet long and I plan to power it with an older DC power pack, but I have questions... namely

1-  what guage wire should I use for this main.? 

 

Unless you are planning on running several hundred lights.......  I would use 16 Gauge.

jacon12

2- stranded or solid?

 

Makes absolutely no difference in practical application.  Which ever you like best for the use.

jacon12

3-  will my old MRC dc power pak be sufficient?

 

Should be.  Again you need to know the current draw of the total lighting on the bus and make sure the pack is rated for a bit more than that.

jacon12

Any other tips/suggestions are appreciated.

 

As others have suggested terminal strips with spade connectors is the easiest route, especially if you want to ever add more or make some changes.  Also I both crimp and then solder the spade lug/wire connections.  Reason?  Often when you crimp only a very small spot is actually making contact.  Some time, a bit of humidity, and some friends over to see and run your RR and you will know why I take about 5 seconds more and solder each spade lug.........

Example.  Not my lighting bus, but you get the idea.

 

[jbinkley60]

jacon12

In the coming weeks I'll be running a bus(s?) beneath my layout to power the lights in various structures.  It will be approx. 40 to 50 feet long and I plan to power it with an older DC power pack, but I have questions... namely

1-  what guage wire should I use for this main.?

2- stranded or solid?

3-  will my old MRC dc power pak be sufficient?

Any other tips/suggestions are appreciated.

Thanks,

Jarrell

I have a lighting bus around my layout.  It is actually 3 buses.  One has fixed 12VDC for control panels, accesory panels and decoders and such.  The second is a swicthed off/on for exterior building lighting.  The third is variable for interior building lighting.  I use 7 conductor 18ga thermostat wire.  It should be plenty large enough for your needs.  Nobody is going to notice a small amount of voltage drop for lighting. 

You might want to run certain sections through toggle switches to be able to turn portions of your lights off/on independently.  I built my own customer DCC controllers for doing this via DCC on my layout.  I use Minatronics 14V 30ma bulbs for my lighting.  They have 15,000 hour rated lives.

 

 

[UpNorth]

14 AWG cable is rated for 5 amps. 18AWG is rated for 2.32A.  18AWG gets 6ohm resistance for 1000 feet.  If you have a layout that needs 1000 feet of cable or pulls 5A with all these bulbs, I envy you.

You will require more than one power pack for any amount of bulbs you put in.  

The power pack is probably rated for  20VA (on the high side). The power pack would be good for 1.6A at 12V ( 20VA / 12 ). So 30 of those little 30ma bulbs will hit 1A.  Since you are going to run them at half the voltage (6V) to save bulb life, you get 3A .

But then you must factore in that  for every bulb you add,  the voltage availlable will drop. So you get to crank up the volts to get the bulbs just right. So your volts have gone up and your availlable amps are going down.

So depending on the number of loads (bulbs), how you wire it all up, you will be faced  with more than one power pack to cover the TOTAL load so you do not overload anything or get so much voltage drop that the bulbs don't  even light up.

Marc F

[jacon12]

 Thanks to everyone for the responses, the tips, suggestions and advice will be a big help.  Now, if you'll take a look at my other thread, Part 2 of this one, I'd appreciate it.

Jarrell