Is 24 gauge wire to small to use for feeder wire?
Thanks
Billy21
For the short runs of rail drops (rail to DCC bus) 24 gauge wire is good for SEVEN AMPERES!!![:O]
Yup. Surprised me, too.
If you are modeling in HO or smaller, or even larger if the locos have modern low-amperage motors, 24 gauge wire will carry the load on any layout smaller than a basketball court. It is more than adequate for Tortoise switch machines, and will even handle the momentary power spikes of twin-coil machines. The only legitimate use for larger wire is in the main power busses of a DCC system.
My own layout is a double-garage filler, analog DC, and wired almost entirely with 24 gauge wire recovered from the dumpster after communications upgrades at a number of places where I was able to liberate it. I haven’t had any problems with it, and am not anticipating any.
Slightly [#offtopic], but important nonetheless. When you wire your layout, document everything. The first time you have to chase down some electrical glitch (and every time thereafter,) you’ll be glad you did.
Chuck (Modeling Central Japan in September, 1964 - and wiring with 24 gauge wire)
‘Good for’ and not too much voltage drop are NOT the same thing. That 7 amp rating is how much the wire can carry without melting. The key to wire use is the ohms per foot resistance, x 2 (complete circuit!) x number of feet x amps. This will give the voltage drop. In this case, a 1 foot section of #24 (total 2 feet of wire) with 7 amps will drop about .36 volts - probably not noticable, so you’re safe. Double that feeder length and you’re up to about .72 volts - that you will see a difference in loco speed. That’s at a full 7 amps. If there is never more than one loco, 1 amp or less, there will be neglibile drop even with 1 foot long feeders
Small wire is perfectly fine - if you KEEP IT SHORT. Consider current draw as well as wire size and length - if there’s a 1 volt drop with 7 amps but your power supply or DCC breaker or DCC booster can only supply 3 amps over that piece of wire, calculating loss at 7 amps is pointless. Try to keep voltage drops under 1/2 volt, and you shoudl be fine.
Here’s a table of wire resistance per 100, 10, and 1 foot: http://www.cirris.com/testing/resistance/wire.html
Remember drop = resistance per foot X length of run X 2 X maximum current. If less than 0.5, you should be fine.
–Randy
For this application, I’d say no. You would be better off (electrically) using a heavier gauge like 18AWG. According to an ampacity table I looked at, the recommended free air current was 3.5A. Changing to 18 gauge increases that to 16A, and reduces the resistance by three-quarters in the process. The side effect is that too much resistance in the wiring can interfere with circuit protection systems.
I wired my layout with 16 gauge bus and 24 gauge feeder wires. I intentionally kept the feeders short. The longest feeder is only about 7 inches long. I haven’t had any problems at all although to be fair I only run 3 locomotives at a time. (Not to say I don’t want to buy more!)
Stewart
Great link, Randy; thanks.
Rick Krall
Hi!
I’ve been known for “overkill”, but after reading all the comments and DCC books about the importance of getting good power to the locos, I am using 14 awg power bus wiring, and 20 awg feeders. So far in my wiring process, feeders are running 8 inches in length - and are spaced every three feet. And, connectivity is checked after each set is installed.
Some may say this is overkill, but this layout (probably my last) will be with me for hopefully a long time. Its predecessor lasted 14 years. My point is, who knows what advances will pop up in the next few years that will have a greater need for heavier wire???
Hey, for what its worth,
Mobilman44
Regarding voltage drop, remember that the current will be divided over the total number of feeders in the circuit. For example, if you have a locomotive drawing 1 amp, and the section of track it is on is connected to four sets of feeders (not blocked by insulators or turnouts), then each set of feeders will have .25 amps of current flowing through them. This is why a locomotive runs better when there are multiple feeders, even when all the track is soldered together.
John
Electricity takes the path of least resistance.
In this case, the most current will be flowing in the feeder nearest the load, and that will change as the load travels down the track. The track has resistance too, and the current will see that in series with the load.
The idea of the multiple feeders is not to spread the current flow, but to minimize the track resistance by placing a much lower resistance in parallel with it. In this manner a moving locomotive is both moving away, and toward a feeder. With just a single connection, as the load travels down the track, the resistance will be increasing until it is at a point (assuming a loop) halfway along the track, then the resistance will decrease as the load moves toward it. Sort of like a potentiometer.
In the case of DCC, a high frequency signal is also going to alter the parameters compared to DC. It doesn’t hurt to do it right the first time. Not to forget the effect of increased resistance on the operation of any electronic circuit protections that DCC likes to use.
I will have to go with Betamax with this one. I rather error on the to big side than the to small side. some of my feeders are way to long, but with them being 18 gage not a problem. On the other hand the new section has 24 gage and cannot keep the track clean, or should I say I have to clean it more often due to the drop in voltage.
To thin of wire can all so effect your booster shutting down. In my case it was because my Bus wire was to thin to the new section. Betamax could explain it if he feels like, but to thin of wires cost me $200.00 in decoders.
Next bench the bus wire will be 14 gage and 18 gage feeders.
By the way, is it gauge or gage? Spell check does not like it spelled gauge but is fine with gage?
Cuda Ken
I still say #18 is too big to solder neatly to HO scale rails. And completely unecessary, especially if you put feeder drops every 3 feet. #20 or #22 is plenty sufficient. But remember we mean FEEDERS not “halfway across the layout to connect to the bus” If you MUST run the wire a longer distance, definitely use something heavier.
As for ‘gauge’ or ‘gage’, either/or. They are interchangeable spellings. I even looked it up to make sure.
–Randy
Another nail in the coffin of the english language.
First the demise of the adverb, next “crispy”, then the bastardized pronunciation of forte’, now an officially recognized dual spelling for gauge.
[sigh]
I’m not shooting the messenger Randy, just getting a favorite rant off my chest. [:)]
Oh yes, 24 ga. is a bit light (or is it lite?) 18 - 22 is fine IMHO.
Karl
While 24 gauge wire is capable of pulling the load you’ll be much better off using something heavier, say 18 gauge. I used 14 guage on mine. That’s heavy enough for household current. The reason for it was that was what I had at the time. The wiring from my control panel and my Zephyr is 18 gauge.
18 gauge is overkill and 14 gauge is just ridiculous unless thats all you have laying around. Like the other poster said use the smaller gauge as it looks much better and is easier to solder to the layout rails. I use 22 gauge and my longest run is about 2’ and I’ve had no problems.
If you’re going to be like Cuda Ken and run 50’ or so feeder wires, then yes, a larger gauge would be necessary.
I’ve been using 14 ga for my power bus and 20 ga for my track feeders. It’s worked very well so far. I’ve also been soldering the track feeders to the underside of the rail rather than along the side.
Tom
Agree with Driline, I use 14 ga. stranded for the buss and 22 ga solid for the feeders. Longest feeders being 2 feet in length. Use a Zepher at 2.5 amps. Gleamed the track two years ago and haven’t had to do it since. Very happy with the results.
I don’t think anyone would disagree with this statement!!! Wish someone had told me that way back when while wiring my first layout. Wish someone had told me that a little later on my second. Wish I figured out it would have been a good idea on my third . . . . As I move forward to tracklaying on my current - I hope I follow this advice!! Gonna keep some sort of standard color code also this time. 