Heavy duty bus and thin droppers??

Hi Nigel.  Thank you, so making a general rule "blindly"? Without knowing the gauge of the wire could drop one into deep water. And at least if one purchases it from a reliable source it shoul be okay? But (not eBay?). But where? because the power poles that I purchased on the eBay site really look lightweight., Maybe I was expecting too much?all the best  Kevin

I use it all the time and for the last 55yrs for everything except bus wire,never had a prob in all that time
:thumbs ;-) :cool:
Owen

Hi Owen.  Thank you for your reply. When you say " You use it all the time and for the last 55 years", what part of the thread is it?? 22 gauge wire, 24 gauge wire , odd unknown lengths of Telecom wire or what?:???::???::???:.all the best Kevin

Hi Kevin,

Telephone wire is fine. Some of the very thin wire used in modern communication devices (USB or JST cables for example) is meant for low current. Using thin low capacity wire is fine until the day a locomotive derails on the frog, shorts it out and full track amperage goes through it. OK with 1.7 amps, not so good with 15 or 20 amps. Bit like putting a screwdriver across the ends of a live socket, interesting things can happen.  I believe you have an NCE Powercab system, there is a reason why there are 2 different cables ("telephone" and coiled). One for power, the other for when the unit is used as a dedicated controller.

I was just reading an article where a Soundtraxx Soundcar decoder (cattle, clickity-click, etc.) was connected to wheel pick-ups in a freight car. The wire used was 30 gauge, which is fine because a sound only decoder doesn't draw that much current (primarily to drive the speaker, 15-20 mAmp) and the risk of shorting out is minimal.

Owen is right, you can use pretty thin wire as long as everything else is OK and you have control over the load they will carry. I take a more cautious approach and if possible go up (down actually) a gauge. You get the benefit of decreased resistance as well. 24 gauge copper is 25.7 milliOhm/foot, 28 gauge is 65, 30 gauge is 103. This translates into heat. Not that important for a frog, which may have current flowing for 1-2 seconds at a time, but droppers (depending on how frequent you have them) could be passing current much longer than this. Wiring does get hot, and this is when the type of insulation used gets important.

This the reason why club set-ups tend to be cautious electrically ,and are wired to minimize resistance and voltage drops and have wiring standards. Careful attention is also paid to how many engines will run at anyone time and what amperage will be required.

Nigel

Edit: There is plenty of information on wire gauge and wiring available. In general, 12-14 gauge for the power bus, 20-22 for the rail droppers, down to 24-30 for things like frogs and sound decoders, lights, speakers, etc. I have a GWR Castle with working oil lamps, they are wired directly to the track pick-ups with 30 gauge enameled armature wire (plus an appropriate resister, these are surface-mount LED's). Horses for courses really. 

Hi Nigel. Thank you for your reply on electrickery. I don't know much about the gauge size of wire that I am using, but,when I resumed the hobby I referred to the forum, and followed the advice there on. At first there was advice about purchasing coils so wire on eBay which I was not completely satisfied with, then I found a "Thread by Max" about stripping 2.5 mm 240 volt cable(twin and earth) for the DCC bus wires, which I did. The droppers quote "I use multi strand cable" unquote.  So I set off to the local electrical dealers and purchased 10 metres of the cable that he had used, but for the droppers, I used regular lighting "multi core" again stripped, the only difference being "Red and Black" in the 2.5mm , and "Brown and Blue" in the multi strand. The Brown and Blue multi strand being the wire of choice for connecting the frog terminal block to the DPDT slide switch centre contact.
The only reason that I mentioned the Telecom cable was "it was of a similar appearance to the frog wire". 
That I will keep for scenery.    all the best. Kevin

Hi Kevin

Can you point me to the thread, please?  I think I must have made a mistake.

The droppers are multi-strand, but 1.0 mm.

Cheers

telephone wire which I was told carried 50vlt at 10amp also alarm cable slightly finer but 5 amp which I use for my street lights
:thumbs  ;-) :cool:
Owen

Hi Max.  At the time? I photocopied the "under baseboard layout and your description of the very neat job". I do have a copy of it on file, but I don't know how to find the thread, otherwise I would point you in the correct direction .Wish I could help you, all the best. Kevin

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

. Bit like putting a screwdriver across the ends of a live socket, interesting things can happen.

Not in DCC of course, all that will happen is power goes off (layout or block, depends on the wiring). :roll:

Nigel

[user=1681]Silver Fox[/user] wrote:

telephone wire which I was told carried 50vlt at 10amp also alarm cable slightly finer but 5 amp which I use for my street lights
:thumbs  ;-) :cool:
Owen
 

Hi Owen,

The following is from Superior Essex, a telecom company:

Voltage and Current Limits for Telephone Wire and Cable Based
on Telephone Operating Company Experience

Maximum Voltage (dc)              Maximum Current

Pair-to-Ground     Pair-to-Pair   (Amps)
150                       300               0.15

Nigel
SaveSave

well you live and learn,my info came from a BT engineer too,still nice to know  thanks
:thumbs ;-) :cool:
Owen

Hi Owen and Kevin,

Tin cans and string never had these issues.

I suspect most of us are are the mercy of those who (may) know better.Then again…volts, amps and ohms are the fundamentals, I try and get my head around them (and err on the side of caution when wiring). We all tend to ignore the other parameter, watts. All those electrons zipping around encounter resistance, and generate heat. Stranded steel wire is a lot cheaper than solid or stranded copper, but does have a higher resistance (40-times more).

One analogy that may be useful is the high density foam cutter. This uses 12-24v, 2-5 amp, 30-ish gauge stainless steel wire, and gets very hot.  Which then of course makes me wonder about local heating of wires in close proximity to foam baseboards. 12 gauge copper bus wires don't have much resistance, 24 gauge droppers however have 16-times more resistance.

Nigel

Hi Nigel.   Thank you , but all these facts are going over my head? although very important, I am pleased to say that I have chosen a Plywood Baseboard. Suffice to say, when my Triang TT 0-6-0 tank model ran round in circles powered by two 6 volt batteries, things were so simple. But back to the 21 st century, when I was using "Vista" or latterly Windows 8, I was able to scan and email a document but "Windows 10 has got the better of me!  (before you ask where is this going or this isn't in the script??).I am referring to my "Twin and Earth Cable" message. Created by Max, he had ask me to point him towards it on the forum, but even though I scanned it at the time, I am flummoxed, otherwise I would scan it and email it to Max.
all the best. Kevin

Hi Kevin,

Basic electrickery is something I believe railway modelers need to understand (even if it's only the relationship between volts, amps and ohms) once the move from train set to model railway is made. It has a direct impact on layout wiring, electric motors and the DCC decoder capacity, especially if you start putting in decoders yourself.

However, If you stick with 12-14 gauge for the bus, 20-24 gauge for the droppers and 24 gauge for the frogs it will work fine. Your NCE Powercab is putting out 2 amp max, and that is the worst case scenario your wires will ever have to handle. With one modern engine 0.5 amp is the most those wires will carry, half that if you are puttering around shunting.

If you have a look at the wiring in an old Triang or Hornby those wires were big by today's standards, motors were inefficient, and all those sparks and burning smells added to the fun. Rail droppers?   We all made do with fish-plates. It's all a bit more precise with DCC, and should we be inclined we can calculate what wire gauge is going to be appropriate. I just use a tried and tested set of standards.

Some of these issues are important, some are interesting to understand. Some are downright incomprehensible.

I came across this great online tool  for calculating wire gauge from voltage and amps. It's for DC, but should be the same for DCC. See http://www.solar-wind.co.uk/cable-sizing-DC-cables.html

Couple of examples that I plugged in with a 1% loss in current:

15v
2 amp
4 meters (medium layout, bus)

Wire gauge = 13

15v
5 amp
10 meters (large layout, bus)

Wire gauge = 5

15v
0.5 amp
0.25 meters (DPDT to frog)

Wire gauge = 26

24 gauge is therefore quite adequate for the frog feed, and gives over-capacity (which is always better than under). Increase the length to 0.5 meters however and 22 gauge wire is needed.

For a dropper wire 2 amp capacity and 1 meter long 19 gauge is needed, for 0.25 meters long it goes to 26 gauge.

Longer wire always means greater resistance, which requires a bigger wire. Which means keeping droppers and frog wires as short as possible.

Nigel

P.S. I use Windows 7, which I note still gets regular updates and fixes. Which means it wasn't ready for real-time when released. Having watched my wife succumb to Windows 10 and then spend the next month getting things back to what they were I'll stick with 7, as 10 is probably getting updates and fixes. The day MS stops supporting 7 is the day I'll switch to something else.



Save

There has always been a slight problem with wire/cable sizes this side of the pond.  :roll:

The UK, always wanting to be just slightly different from the "others", although in fact, I think the whole of Europe, uses wire diameters in "everyday" use, not gauges.  We refer to a wire being 0.2mm or, in the case of domestic house wiring, 1.0mm, 1.5mm, 2.5mm, 4mm and so on.

I always have to look up "our" equivalent to a gauge size …………………………plus, gauges are not "logical" in that the thicker the wire, the smaller the gauge.  :???: :???: :???:

Hi Peter.    Thank you, or should that be merci ? I never got beyond "schoolboy French". But in my humble opinion it was a mistake to get involved with Europe , but once we did ,I believe that it was Europe that should have toed the line, never mind metrification or decimalisation. The UK had already tried that,with the "Florin", the old two bob, and decided that it was better with  pounds, shillings and pence . At least we still have proper "three pin plugs" it was a pity that the colours of the wire had been messed with . Stick with what you know! That is why I only know franglais ?"Vive La Difference". Sorry for my difference of opinion?  all the best "Bon Chance"?   Kevin

Something I typed up ages ago from various sources.

Bit approximate, but may be of use as a rough guide.





Ed

Hi Ed.  Thank you, with all this useful information flying about, I had better study how to "fax and scan" on my Windows 10. I don't know why I went for 10, Windows 8 was much easier. all the best. Kevin

Hmmm, Windows 10. Brave man Kevin and definitely a case of bon courage rather than bon chance!

Hope the day treats you well,

Bill :)

Hi Bill.  Thank you, Too true, but when I kept getting bombarded with messages I eventually capitulated? What a wallyall the best. Kevin