What size wire?


C

Chemdawg

Member
I need to buy the wire to hook everything up on my layout. Here are some specifics:

Digital zephyr
Two digitrax pm42's for 8 districts
Three digitrax ds64's for 11 turnouts.

What gauges of wire should I use? Solid or stranded?
 
For bus wires, most use 12-18 gauge. The longer the runs, the larger the wire. Personally, I like stranded wire for the bus.

For track feeders, most use 18-22 gauge. I use 22 gauge solid for feeders on my N-scale layout. You could comfortably use 18 gauge for HO. I find solid wire much easier than stranded for soldering to the track.

- Jeff
 
I don't really know your lengths of run, but you should be well served with a stranded bus of about 16 gauge...meaning the mostly-clear plastic insulated speaker wire, one copper, the other steel or aluminum. You get those as bundles at Radio Shack. Also at RS, get the four-wire 22 gauge cable in white plastic casing on a spool. The wires are insulated red, black, green, and yellow. Each one makes great feeders. They are solid copper.
 
I have a double main of 44 feet each. I also have my yard and a few other feet here and there. When your talking bus wire, where does that come in with the pm42? That's how I make my districts. Those are mounted real close to my zephyr. Within 4 feet I would say.
 
Run four feet of 16 gauge to the PM42, and use that gauge for its outputs to your districts. Once you reach the districts, run feeders off each bus wire, one feeder per rail coming off each pair of your bus wires.
 
If I was running a buss wire around the track, I would do it in 12 gauge and then not worry about it for the rest of my life. You don't really say how long the runs actually are and resistance builds with distance.

Railroads tend to get bigger, not smaller. Wire now for expansion IMHO.
 
I dont remeber if you are using dcc or not, but if you are be sure to twist your wires around each other. 2 twists per foot or more, this will prevent cross talk in the wires. Allso, you may want to keep the bus runs shorter than 25 feet.
 
Let us not forget that our wires essentially parallel the entire runs of rails, themselves not-so-great conduits for electricity. Yet, we never worry about how much rail we have on our layouts, do we...in fact, more is preferrably to many of us. So, if the rails don't seem to have much of an impact on the passage of electricity, why should the larger gauge wire below it? 16 gauge wire is plenty robust, and is larger than what is found in your common 50' garden extension cords. There are no expressions of concern about the lengths of 50, even 100' extension cords of the type commonly used at construction sites to power 10 amp reciprocating saws and table saws.

Go light, keep it simple, no need for trans-oceanic gauge cable for your 25-40foot runs on a layout.
 
My experience with long cord runs on power tools is different. The longer the run the bigger the gauge needs to be or you will see voltage drops which will cause power tools to overheat and fail. The NEC specifies those calculations and I don't have them handy but I know they exist. My runs from the main shop to the lumber storage sheds are in #8 because of the distance- about 120 yards and that is for a simple table saw.

My point was to not have to come back and re do it ever.
 
Selector said:
Let us not forget that our wires essentially parallel the entire runs of rails, themselves not-so-great conduits for electricity. Yet, we never worry about how much rail we have on our layouts, do we...in fact, more is preferrably to many of us. So, if the rails don't seem to have much of an impact on the passage of electricity, why should the larger gauge wire below it? 16 gauge wire is plenty robust, and is larger than what is found in your common 50' garden extension cords. There are no expressions of concern about the lengths of 50, even 100' extension cords of the type commonly used at construction sites to power 10 amp reciprocating saws and table saws.

Go light, keep it simple, no need for trans-oceanic gauge cable for your 25-40foot runs on a layout.
Click to expand...

My layout uses 14 ga. wire for Busses & I wish I had started w/12 ga. From my transformer to the back of the layout is about 35 feet. When I run 4 engines & about 70 cars I have a voltage drop back there. Just recently an Electrician did a complete check of my whole layout as I was running trains.
He said I need to change the wire to the fartherest part of the layout to 12 ga. stranded. I have a terminal strip just below my main transformers that I run the Buss wires from to diff. parts of the layout. I started out w/one continous Buss right at the beginning & that didn't seem to have the response that I needed. So, I changed it to the seperate Buss wires.
I only run HO scale. So, this summer I'm changing the main wire to 12 ga. to the fartherest point & leaving the 14 ga. to the nearest points.
If I was running DCC I would run 12 ga. for sure & 10 ga. to the longest part.
I run multiple trains on 1 mainline all the time.
 
I think what I'm going to do is run 16 gauge from my power supply to my PM42's. Instead of putting all the electronics in one central spot, I'm going to run buss wires around each side of the table, and put a PM42 on each end. That way the feeder wires don't have to be super long. I will use 18 gauge for those.

My layout is a duck under. NOT too big. 8 X 13. It's about all I could afford in real estate in my recroom.

I am using a PC power supply to power my PM42's and possibly my DS64's. Since everything is loconet, I don't necessarily have to have everything sitting together. It would sure be nice to have everything central though so I can see the panels if there is a problem.
 
I ran a loop of 12-2 Romex around my layouts main line under the bench work for my bus. It's fairly cheap, color coded and easy to work with. I just open the jacket where I want to make a connection to the track and solder them onto the main bus wires.

picture.php
 
At 8x13 feet, 14 gauge should be fine. Use stranded if you can IMHO.

You can also get these little scotchlock connections that they call suitcase clamps which run a feeder wire and your buss wire in the same connector. It's like a little compression saddle. I found them at Home despot.
 
This chart and calculator say that a 30' run of 16 gauge wire carrying only 12 volts and delivering 5 amps will suffer a voltage drop of 1.2 volts. Our DCC systems in HO deliver about 15 volts, so you may end up with about 1.0 volts drop...the calculator doesn't have that finely discrete a range of settings, so I am guessing.

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

The note above the chart states that the amperage rating "...is very very conservative." Ambient temperatures, insulation type and warmth, and other factors may degrade the ability of the wire of a given gauge to conduct power.
 
Selector said:
This chart and calculator say that a 30' run of 16 gauge wire carrying only 12 volts and delivering 5 amps will suffer a voltage drop of 1.2 volts. Our DCC systems in HO deliver about 15 volts, so you may end up with about 1.0 volts drop...the calculator doesn't have that finely discrete a range of settings, so I am guessing...
Click to expand...

The voltage drop would be the same at 15 volts, or 20, or 100. The voltage drop is a product of the current and the resistance of the wire, and does not vary with the source voltage.
 
Pete V said:
At 8x13 feet, 14 gauge should be fine. Use stranded if you can IMHO.

You can also get these little scotchlock connections that they call suitcase clamps which run a feeder wire and your buss wire in the same connector. It's like a little compression saddle. I found them at Home despot.
Click to expand...

Please don't use these connectors; when used on solid strand wire the actually cut a grove in the wire that are joined together. and when used with stranded wire that will actually cut the strands of wire thus resulting in the load of the wire (capability of the wire to carry its' complete load) being reduced and they will also oxide over a period of time eventually cutting the power through them off.

Jim
 
UPBigBoy said:
Please don't use these connectors; when used on solid strand wire the actually cut a grove in the wire that are joined together. and when used with stranded wire that will actually cut the strands of wire thus resulting in the load of the wire (capability of the wire to carry its' complete load) being reduced and they will also oxide over a period of time eventually cutting the power through them off.

Jim
Click to expand...

What would be a good alternative to use? We are very close to putting down and wiring up the track, and this thread has been very helpful. I thought about stripping an inch of the bus wire, and looping the feeder wire around that and electrical taping it, but that seems like a pain, especially doing it about 50 times... lol
 
Im sure there are more elegant ways of doing this, but i just cut my bus wire then connected them back together along with the feeder wires with wire nuts. I allso taped the nuts tightly with electrical tape after the connection was made. I made three feeder wires at every connection.
 
TRAINFAN9510 said:
What would be a good alternative to use? We are very close to putting down and wiring up the track, and this thread has been very helpful. I thought about stripping an inch of the bus wire, and looping the feeder wire around that and electrical taping it, but that seems like a pain, especially doing it about 50 times... lol
Click to expand...

Sounds to me like a good opportunity to polish your soldering skills. :)
 
You can get wire strippers that also displace insulation along your bus wire at intervals of your choosing. You wrap the bare end of a feeder around the bared bus wire and solder that connection. Takes a minute per connection once you are on a roll. If done well, the soldered joint will last indefinitely.
 
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