Heavy duty bus and thin droppers??

Hi All.   As I understand it, from watching YouTube videos on DCC, the bus must be heavy duty, but the droppers from the rails are a lot thinner(please excuse my poor terminology). And I , (like a lot of other modellers) am using Peco Electrofrog points, but I noticed how "thin and fragile" the frog wire is, I appreciate that there must be a good reason for this, and if that wire is so thin then the wire(in my case is connected to a DPDT slide switch) connecting it to the point motor can be as thin. My question is "Why such a variation ? Three different gauges of wire, all carrying the same? current.     all the best. Kevin

Hi Kevin

Think of it like water pipes.

The mains are much bigger in diameter than the pipes in your bathroom.

The bus is carrying the current for the whole layout, while the wires in the frog are only supplying those wheels which are on the frog.

The more water flowing in the mains, the larger diameter pipe you need to get all of the water through for everyone.

The more current you have, the larger the diameter of the wire you need to keep the resistance low.

Cheers

Hi Max.   Thank you for your reply, it sounds so simple when you put it like that.   all the best. Kevin

[user=269]MaxSouthOz[/user] wrote:

Hi Kevin

Think of it like water pipes.

The mains are much bigger in diameter than the pipes in your bathroom.

The bus is carrying the current for the whole layout, while the wires in the frog are only supplying those wheels which are on the frog.

The more water flowing in the mains, the larger diameter pipe you need to get all of the water through for everyone.

The more current you have, the larger the diameter of the wire you need to keep the resistance low.

Cheers

That's a great description Max  :thumbs

Tony.

Thanks, guys.   :cool:

Will the water leak out if I cut the insulation …………………….?   :cheers :cheers

Great analogy Max.  Most people (me included) can understand water but fail on electricity - probably because you can see water rather than just having to imagine it ………… :roll: :roll:

Hi Kevin,

Nice analogy from Max.

It all depends on the current draw at the point of operation.That thin wire to the frog is 25 gauge wire (I measured the one on a Peco Code 83), it's good for at least 0.45A (0.457A for pure copper) and more realistically somewhere approaching 3.5A.The current draw on a large OO engine running across the frog is probably 0.2-0.5A. And that is not continuous, so heating of the wire is not an issue.



Nigel

[user=1632]BCDR[/user] wrote:

Hi Kevin,

Nice analogy from Max.

It all depends on the current draw at the point of operation.That thin wire to the frog is 25 gauge wire (I measured the one on a Peco Code 83), it's good for at least 0.45A (0.457A for pure copper) and more realistically somewhere approaching 3.5A.The current draw on a large OO engine running across the frog is probably 0.2-0.5A. And that is not continuous, so heating of the wire is not an issue.



Nigel

Nigel, is what you said correct ?  frog wire good for 0.45A and more realistically approaching 3.5A

Hi Nigel. Thank you for your reply , that explains a lot. But why is such an important piece of wire so fragile?Maybe it is a "ruse" to sell more sets of points , I have three sets that I needed to repair after changing my plan.
all the best. Kevin

Hi Ron.   Everyone is getting very technical today, is that milliamperes or what? it is all Chinese to me.The" Black Art" of DCC strikes again??    all the best. Kevin

Kevin   0.45A = 450  milliamps    DC , AC  or  DCC - it is all the same

Hi Ron,

That's what the tables say. 

American Wire Gauge Chart and AWG Electrical Current Load Limits table with ampacities, wire sizes, skin depth frequencies and wire breaking strength

24 gauge, 3.5amp for chassis wiring, 0.577amp for power transmission. Somewhere in this range will be the reality.

This is for soft copper wire. Multicores have lower capacity.

http://www.engineeringtoolbox.com/wire-gauges-d_419.html

And of course:

Transwik

Nigel

Hi Kevin,

If the original wires put there by Peco have come adrift from the underside of the frog, and you're worried about replacing with gauge 24 wire (as you know I use 24 gauge tinned wire ready for soldering),just replace with 22 gauge wire (or whatever wire you're using for the rail droppers). That will give you 0.92amp. Anything bigger than 22 gauge (20 for example) is getting a bit big, unless you start hacking the plastic around the existing access hole to the frog underside. Of course you can just hold the tip of the iron in the hole - the diameter will increase dramatically.

Nigel

Thanks Nigel, learning new things each day,

Hi Ron.  Thank you, I was thinking that when the Telecom engineers are working around junction boxes they leave behind lengths of fine wire, which until now I have been collecting for scenic effects( trunking etc ) but that wire is very similar to the frog wire. Could that wire be good be good enough to extend the frog wire the two or more feet to the DPDT slide switches that I use for point control?? I could have a fire extinguisher handy just in caseLOLall the best. Kevin

Hi Nigel.  Thank you. I am a complete "Bodger", alas there is no "Finesse" with my work. I have been bullying regular wire into the underside of the frog and soldering, hoping for the best, one idea I came up with, terminal blocks under the baseboard , for the junction between the two wires, which I hope would make things easier. all the best. Kevin

[user=1801]Passed Driver[/user] wrote:

Hi Ron.  Thank you, I was thinking that when the Telecom engineers are working around junction boxes they leave behind lengths of fine wire, which until now I have been collecting for scenic effects( trunking etc ) but that wire is very similar to the frog wire. Could that wire be good be good enough to extend the frog wire the two or more feet to the DPDT slide switches that I use for point control??

YES

Hi Kevin,

Terminal/barrier blocks? Yes, it's a good idea for several reasons. No splicing of the power bus, easy to move dropper leads around (track and DPDT switches), if you use 6-8 terminal ones you can add a DC bus and still have 4-8 terminals for droppers. Run a 240v circuit and have a socket for the kettle. Label the wires.I use 30amp double row blocks that take 10-22 gauge wire.

Mount them 3-4 inches from the end of the module to the underside of the top. It's a good idea to standardize on the length of the droppers, that way resistance and voltage drop is constant. If you mount them parallel to the sides of the module rather than parallel with the ends it's a lot easier poking wires into the terminals, and you can have them flush to the ends. There is no reason why they have to be parallel to the ends. I use Powerpoles from the terminals to connect modules.

Get the big ones as you will have several leads connected to the same terminals (power bus in/power bus out, dropper(s) out, and if necessary daisy-chain smaller ones off the big ones (power bus out, power bus to dropper block out).

Nigel

Hi Nigel.  Thank you for your reply. I had only thought about using terminal blocks for the frog wires. But with a stretch of the imagination ? The possibilities are endless.   all the best. Kevin

[user=606]Sol[/user] wrote:

[user=1801]Passed Driver[/user] wrote:

Hi Ron.  Thank you, I was thinking that when the Telecom engineers are working around junction boxes they leave behind lengths of fine wire, which until now I have been collecting for scenic effects( trunking etc ) but that wire is very similar to the frog wire. Could that wire be good be good enough to extend the frog wire the two or more feet to the DPDT slide switches that I use for point control??

YES

Hi Ron and Kevin,

MAYBE. This is a "devil in the detail" one. Telephone wire is either 22 or 24 gauge,  :thumbs :thumbs :thumbs,telecommunication wire such as RJ12 (computers, your layout, etc.) is 28 gauge and is only intended for low voltage/low current applications such as sending signals. AWG says 1.4 amp chassis wiring, 0.23 amp power line. Hmm. Borderline at best. Ethernet cable (Cat5 for example) is 24 gauge (and a lot of it)  :thumbs :thumbs. If Ethernet cable or telephone cable is going for free, it can be re-purposed. You get some funny colors though with and without stripes. Use labels attached to each wire JIC, because 6-months down the road and you will be having an "oh dear" moment or three.

You can get spools of 22 or 24 gauge wire for a couple of groats. And zero time getting it out of a multiwire cable and deciding which shade of puce to use next.

Nigel
Save