wire size from nce power cab?


J

joed2323

Member
Ok guys i have a nce power cab and im getting closer to installing it on my layout after i get
my feeders soldered to my bus wire.

I used 14 gauge for my bus and 18 guage foe my feeders.

I played around before with my nce power cab on a simple test track but i had to use 18 guage or smaller wire to get the wire hooked up into those tiny little wire ports on the back side of the power panel.

So my question is whats the proper wire size to supply power to my bus wires from the power panel?
To me it seems like i could never get my 14 gauge bus wires to fit in those tiny ports, unless im slow and didnt try hard enough?

Should i just use 18 guage from power panel to the 14 gauge bus wires feeding my track? This way seems wrong since im using Small wire to supply power to bigger size wire!

Thanks guys, any help would br appreciated
 
Funny, I just did this recently. The 14 awg is indeed a pain to get into the pcp panel track wire contacts, but it will work. Try to use a short run from the track wire contacts to the bus. You can connect this short run to the 14 awg bus easily by using those screw on wire nuts.
 
If the smaller wire is short then it is ok.

The heavy gauge wire that is recommended for DCC is not for current carrying as in your house wiring it is to reduce the I*R voltage loss. A heaver wire has less resistance.

How long is your 14ga buss and how long are each feeder and how long would be the connection from the command station/booster to the buss?
 
I probably have atleast 2 50 foot bus runs approx, under 50 for sure, each

I have enough 14 guage buss wire to run it straight up to the back on the nce power panel and then some, gave myself wiggle room.
So that connection could be as short or as long as i need.

Each of my feeder wires feeding each section of track is probably no longer then a foot.
 
Last edited by a moderator:
Ok. If the 18ga connection from the NCE panel to the buss is less than two feet all should work fine.
 
Can you explain why using the 18awg from the power source to the 14awg bus doesn't increase the resistance as long as the 18awg run is short? It's not intuitive certainly.
 
Yes thats a good question??

Maybe cutting a few strands off the 14 guage and snaking the 14 guage into the power port might be better then using 18 guage for a short run???
 
Ken Portner said:
Can you explain why using the 18awg from the power source to the 14awg bus doesn't increase the resistance as long as the 18awg run is short? It's not intuitive certainly.
Click to expand...

From a wire chart:
http://en.wikipedia.org/wiki/American_wire_gauge

Wire resistance is measured in Ohms per some unit length (column 6, Ohms per kilofoot or milliOhm per foot).
For 14ga its 2.525 mOhm/ft
for 18ga its 6.385 mOhm/ft

A 50 ft length (I'm only considering one half of the circuit since I am looking at the ratios) of 14ga is a total of 0.12625 Ohms
A 1 foot length of 18ga is 0.006385 Ohms which is almost 20 times less.
The total resistance for both is 0.1268885 Ohms so the short piece of 18ga barely increases the total resistance.

Another way is looking at the voltage drop across the wires.
Assume a 5 Amp booster and enough engines and accessories to draw the full 5Amps, all at the end of the 14ga bus.
The voltage drop on 50ft of 14ga is R*I or 0.12625 Ohm * 5 A = 0.63125 Volts
The voltage drop on a foot of 18ga is 0.006358 Ohm * 5A = 0.03179 Volts which is negligible compared to the drop on the 50ft of 14ga.
Even a 2 ft length of 18Ga drops only 0.06358 Volts with a 5 Amp load.

Ok, without considering the 14Ga buss, the voltage drop on the short 18ga is still negligible compared to the full voltage from the booster of 12 to 15V.

Does this make sense now?
 
Thanks waltr, makes more sensr now. Now i can take the easy way out tonight and hook uo my nce power cab power panel and splice in a short section of 18 guage from 14 guage to the panel and be done with that and move on to thd next hurdle.

I appreciate your help you guys :)
 
I guess my mistake is thinking of electricity as water and the wires as pipes. A smaller pipe allows a smaller flow over the same period of time.
 
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