Mike Nowakowski
Member
Is a 18 gauge feeder wire spaced 4ft apart on a 12 gauge 40 ft long bus good.
Feeder wires
- Thread starter Mike Nowakowski
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I handlay or use flex track and put a feeder to each individual rail. All my rail joiners do is hold the ends together.
It's actually voltage drop that is the issue. Smaller gauge wires drop voltage in much shorter distance with low voltage. Since the wire becomes part of the circuit, if the voltage drops enough, the circuit breaker or protection circuit cannot tell when there is a short circuit and won't shut off. This can result in damaged equipment or decoders that require some re-programming since the dcc signal gets compromised.
Precisely...the whole point of DCC is to also impose a signal on the current to the rails that the decoder can make sense of. Back at the base controller, it must be able to sense a change in the wiring system so that it knows to shut off power to the rails if there is a short way out in the far reaches. Significant drops of voltage in DC just mean slower trains and dimmer headlamps...boo hoo. Substantial drops in voltage on DCC layouts means the system may permit a nasty short to persist, at which your expensive decoder and you both do a very big BOO HOO. Decoder then gasps, emits its magic smoke, and you might as well remove that loco if for no other reason than it is still causing a short.
26 gauge wires would be fine if they were very short and not intended to carry more than about 1 amp. I don't honestly know what that means, but short would be less than 6-8", and you would need a great many such hair-thin feeders to supply strong usable voltage for all the purposes we have mentioned.
The wisdom across six fora that I frequent is that your bus wires seldom need to be much heavier than 16-14 gauge. They'll handle 8 amps well.
Feeders should be in the 20-22 gauge range, be kept as short as practicable (less than 2' is ideal), and should run to the rails about every 6'-8'. If they are also soldered, you are virtually assured of perfect continuity (barring turnout problems), and also safe detection of shorts.
-Crandell
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cncproadwarrior
North of the 49th
It'll work but sounds like overkill to me. I used 14 gauge 40' bus with 22 gauge feeders every 3-4 feet on a 12x8 layout with about 250' of track.
Selector
Well-Known Member
A single feeder pair will handily power an oval of properly joined rails totaling 16'. Sure, there will be a bit of voltage drop-off on the farthest point opposite of where the feeders join the rails, but maybe only 1/2 volt....barely noticeable.
The best and safest application of joiners is short ones in the 20-22 gauge thickness, and soldered to soldered joiners. However, logically you only need every other joiner pair done that way. The rest should be left to allow the rails to slide so that expansion can be accommodated...contraction, too. The rails have to move at times. By soldering every other joiner pair you assure yourself of 100% continuity in either direction until the next joiner. The joiners on either side aren't needed for continuity...only for alignment.
-Crandell
The best and safest application of joiners is short ones in the 20-22 gauge thickness, and soldered to soldered joiners. However, logically you only need every other joiner pair done that way. The rest should be left to allow the rails to slide so that expansion can be accommodated...contraction, too. The rails have to move at times. By soldering every other joiner pair you assure yourself of 100% continuity in either direction until the next joiner. The joiners on either side aren't needed for continuity...only for alignment.
-Crandell
Mike Nowakowski
Member
My DCC control system wires are 26 gauge and its going into a 12 gauge bus, is the 12 gauge bus really nessary when you can only get the same voltage through the 26 gauge line.
Im just a novice, but there seems to be way too much overkill about needing a big bus wire guage, feeder wires every 4 feet, and soldering every joint. I dont know, maybe the experts saying this have huge, huge layouts and operate 10 cabs at once. Or maybe they get a kickback on wire and solder gun sales (ha ha).
I have a 11 X 6 layout and have mostly 20 and 18 guage wire on the track bus with some 20-22 guage feeders. My cab bus is 14 guage. All flex track is soldered, feeders about every 6 feet. No problems yet...
I have a 11 X 6 layout and have mostly 20 and 18 guage wire on the track bus with some 20-22 guage feeders. My cab bus is 14 guage. All flex track is soldered, feeders about every 6 feet. No problems yet...
Sure.
I handlay or use flex track and put a feeder to each individual rail. All my rail joiners do is hold the ends together.
BigB you are quite right...much overkill when you think only of current ratings of wire. Generally, a 14-16awg bus will be optimum for an average sized layout. Smaller wire may have the current rating, but that doesn't mean it is best for the layout if the voltage drop of the wire has to be considered. I use 12awg solid bus because of layout size and because the layout is used for Op sessions with many trains. I like the solid conductor for the ease in shaping/forming around corners,etc, of the benchwork and what I find to be easier soldering for the drop feeds.
All my track drop feeds are 22awg wire and are generally spaced 6-9 feet apart, joiners soldered. What many don't realize is the current is divided to the track through all these feeds, so no one pair is handling that much current at any one time (Voltage drop of these short feeds isn't even a factor.) The idea of "more feeds the better" is mostly to eliminate potentially bad track connections by supplying power to more points and hopefully having power on both sides of those connections. Soldering joiners is a way to eliminate many of those feeds.
Mike: Are you sure, 26awg? That is very small for any system, particularly when we use 28awg for signal lights. That is smaller than most telephone wire (24awg).
All my track drop feeds are 22awg wire and are generally spaced 6-9 feet apart, joiners soldered. What many don't realize is the current is divided to the track through all these feeds, so no one pair is handling that much current at any one time (Voltage drop of these short feeds isn't even a factor.) The idea of "more feeds the better" is mostly to eliminate potentially bad track connections by supplying power to more points and hopefully having power on both sides of those connections. Soldering joiners is a way to eliminate many of those feeds.
Mike: Are you sure, 26awg? That is very small for any system, particularly when we use 28awg for signal lights. That is smaller than most telephone wire (24awg).
hamltnblue
Active Member
It's actually voltage drop that is the issue. Smaller gauge wires drop voltage in much shorter distance with low voltage. Since the wire becomes part of the circuit, if the voltage drops enough, the circuit breaker or protection circuit cannot tell when there is a short circuit and won't shut off. This can result in damaged equipment or decoders that require some re-programming since the dcc signal gets compromised.
Selector
Well-Known Member
Precisely...the whole point of DCC is to also impose a signal on the current to the rails that the decoder can make sense of. Back at the base controller, it must be able to sense a change in the wiring system so that it knows to shut off power to the rails if there is a short way out in the far reaches. Significant drops of voltage in DC just mean slower trains and dimmer headlamps...boo hoo. Substantial drops in voltage on DCC layouts means the system may permit a nasty short to persist, at which your expensive decoder and you both do a very big BOO HOO. Decoder then gasps, emits its magic smoke, and you might as well remove that loco if for no other reason than it is still causing a short.
26 gauge wires would be fine if they were very short and not intended to carry more than about 1 amp. I don't honestly know what that means, but short would be less than 6-8", and you would need a great many such hair-thin feeders to supply strong usable voltage for all the purposes we have mentioned.
The wisdom across six fora that I frequent is that your bus wires seldom need to be much heavier than 16-14 gauge. They'll handle 8 amps well.
Feeders should be in the 20-22 gauge range, be kept as short as practicable (less than 2' is ideal), and should run to the rails about every 6'-8'. If they are also soldered, you are virtually assured of perfect continuity (barring turnout problems), and also safe detection of shorts.
-Crandell
hamltnblue
Active Member
Here's an article on voltage drop per foot for different sized wires and for Nickle silver track. Note how high it is for the track. .34 volts per foot at 4 amps!!! Note you have to use the highest value since that's what is drawn when there's a short.
http://www.wiringfordcc.com/trakwire.htm
http://www.wiringfordcc.com/trakwire.htm
Crandell/HBlue: I may have read Mike's post wrong, but I thought he was saying he is coming out of his controller with 26 awg to the 12awg bus. I didn't read it as his track drop feeds. If indeed, he is coming direct from his command center with 26awg, it is the weak link with all the current going through it and he will have a very hot wire when running several amps.
When we talk about size of the bus wires, as you and I noted: 14-16awg is sufficient for the average size layout, but we should also mention "the bigger the better". Larger wire has less resistance and doesn't cost that much more. Needed or not...it is better to be too large than too small. 12awg is probably larger than needed on most layouts, but it doesn't hurt a thing to use it. With large bus we are talking wire resistance and not current capability.
20-22 awg is ideal for drop feeds. As I noted, the current divides itself through each jumper with the most going in the path of least resistance, ie loco in middle of section between two feeds = almost even current through those feeds with near that amount going through all the other feeds. Not much for any single feed.
Voltage values does not trip the breaker on any of the command modules I am aware of, excessive current does. If the "coin test" doesn't trip the breaker, then I would bet you have a lot more wrong than too much resistance in the wiring or track; probably bad connectors. Crandell, you said it all when mentioning good track work and soldering connectors.
I also have read the reports on N/S track resistance with OPSIG having the most detailed. Again, with proper track installation, soldering joints, and a reasonable amount of track feeders, this shouldn't be a problem. How far away will the loco be from a track feeder. I have had as much as 20 feet without any feeds and didn't have any noticeable (lights operation) drop in voltage.
When we talk about size of the bus wires, as you and I noted: 14-16awg is sufficient for the average size layout, but we should also mention "the bigger the better". Larger wire has less resistance and doesn't cost that much more. Needed or not...it is better to be too large than too small. 12awg is probably larger than needed on most layouts, but it doesn't hurt a thing to use it. With large bus we are talking wire resistance and not current capability.
20-22 awg is ideal for drop feeds. As I noted, the current divides itself through each jumper with the most going in the path of least resistance, ie loco in middle of section between two feeds = almost even current through those feeds with near that amount going through all the other feeds. Not much for any single feed.
Voltage values does not trip the breaker on any of the command modules I am aware of, excessive current does. If the "coin test" doesn't trip the breaker, then I would bet you have a lot more wrong than too much resistance in the wiring or track; probably bad connectors. Crandell, you said it all when mentioning good track work and soldering connectors.
I also have read the reports on N/S track resistance with OPSIG having the most detailed. Again, with proper track installation, soldering joints, and a reasonable amount of track feeders, this shouldn't be a problem. How far away will the loco be from a track feeder. I have had as much as 20 feet without any feeds and didn't have any noticeable (lights operation) drop in voltage.
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Mike Nowakowski
Member
I have part of the layout running on it, it works good for now but in the future i am going smaller.
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