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Hi All,

I'm quite new to railway modelling, and I'm just about to wire my first layout. In order to apply power to the track and to my turnouts I recently purchased some 7/0.2mm wire from Rapid Electronics. I'm working in N scale, and so I suspect that anything meatier than this would be over the top (over rated). This is, by the way, a small layout at 3' by 6'. Is this a reasonable assumption or as a newby should I be working with large gauge wires? I find the 7/0.2mm wire hard to strip cleanly, however I have been advised that an adjustable stripper would do the job better.

I would be interested to hear your advice, please.

Best Regards -- David Baker.
 

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QUOTE (scotterdavid @ 19 Jan 2009, 17:15) <{POST_SNAPBACK}>Hi All,

I'm quite new to railway modelling, and I'm just about to wire my first layout. In order to apply power to the track and to my turnouts I recently purchased some 7/0.2mm wire from Rapid Electronics. I'm working in N scale, and so I suspect that anything meatier than this would be over the top (over rated). This is, by the way, a small layout at 3' by 6'. Is this a reasonable assumption or as a newby should I be working with large gauge wires? I find the 7/0.2mm wire hard to strip cleanly, however I have been advised that an adjustable stripper would do the job better.

I would be interested to hear your advice, please.

Best Regards -- David Baker.

Hi David,
Welcome to the forum


An automatic wire stripper is the tool you need as here with one squeeze the wire is left clean and ready to solder

http://www.maplin.co.uk/Module.aspx?ModuleNo=45237

They can be found cheaper many times at car boots.
 

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**** Are you using DC or DCC David? To be honest 7/.02 is marginal on either really, but is definately far too small for DCC track bus wiring.

It is WAY too small for turnout motors - for that you need at the very least double the size, preferably larger (voltage drop will be an issue - a peco or seep point motor draws about 4 amps momentarily and over any length of that small wire, you will lose a lot of voltage)

Richard
 

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7/02 wire has a maximum continuous current rating of 1.4A and a resistance or .1 ohm per metre. While it can handle much higher currents for a very short time the voltage could be a significant factor. For instance, 0.5A over a 2m length will give a voltage drop of 1 Volt; hardly significant for traction. Point motors take much higher currents. However, if you are using a CDU with a reasonably high voltage, there should be no problem unless you are using route switching, in which case, the wire supplying the diode matrix should be heavier duty. Also, you might have problems with a long wire run feeding two points (as in a crossover with linked points switching).

Reference: Model Rail Forum > The Engine Sheds - Community Forums > Tracks, Layouts & Scenery > Wiring for pont (sic) motors, last post 14th April 2008.
 

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***Chris: Literal translations of linear impedance are not useful for what we do if long term reliability and best performance is the objective. I see myriad problems with underwired layouts, virtually none with those wired to good standards. Compromise has a cost.

(1) Modellers make imperfect wiring usually - and even when well done, each soldered joint is resistive. Using a linear calculation for wire voltage drop is useful for calculating circuit design such as coil impedances but not for model railways. There are too many other factors.
(2) For example if we use AC then the inductance of the two wires which complete the circuit greatly increases the linear impedance and voltage drop will be magnified many times. Drops of 15~25% would be reasonably expected with fine wire to an AC coil depending on how the wires are run on an average layout.
(3) The momentary current draw of a PL10 peco point motor is 4 amps minimum. If the switch sticks, then 7/.02 will literally burn off the insulation as it fails. We should be using wire which has at least double the maximum current expected for point motors - and that is very much larger than 7/.02
(4) If DCC is being considered at any stage, now or in the future, it would pay to wire more heavily....With DCC, 7/.02 is marginally OK for short droppers or low current devices like LEDs or detectors but not enough for any other part of the layout.

regards

Richard
 

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Hi everybody, I also are new to modelling and am just about to start a small (1.5m x 0.9m) layout as a trial, full DCC with all electrical items fitted with decoders.

I read the replies to scotterdavid's post and am confused - what is the best spec. for the wiring if the 7/.02 is too "light"? My trial layout will gave 9 points, 2 uncouplers, and two trains.

Also, can anyone recommend a good book or guide for beginners, particularly for the electrical side of things?

I will be very grateful for help in this area.

I am looking forward to read on this forum as I am sure it is full of wise and helpful information.

Pimkib
 

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Hi Richard.

I note your comments which are, of course, valid as a general statement. However, I was taking into account two things, maybe erroneously. One was that David does not mention DCC so I assumed that he is operating in DC; I know virtually nothing about DCC, my one foray with it being not very satisfactory. Secondly that he is using a small layout. (I ought to add a third to that - namely that his layout isn't going to be subjected to rigours of the exhibiiton circuit.) My experience of modelling is limited; I built several 'layouts' some 50-45 years ago but not having much money none every got finished. I built a layout 20 years or so ago that was 13' x 8' HO and used 7/02 for the track power with no adverse results. I am in the process of building a new Z scale 6' x 2' layout and am, again using 7/02 as all the runs are very short so straightforward resistive drops are not significant and, as it is DC, AC is only present in signalling and lighting circuits. (I note that the Viessmann Z scale semaphore signals work fine on 10Vac, just over half the recommended 16Vac so, at 50Hz, not a problem.

(1) Yes, point taken. I am well used to using a soldering iron on electronic circuits and have an Weller iron that is temperature controlled. So the only time I have a problem is when I solder to track though even there I am getting better at it. Joint resistance could be a problem with dry joints etc. I haven't checked the resistance of my solder joints but I might do that some time to see exactly how much it is (hopefully negligible).

(2) Again, taking the specific layout and assuming the use of DC for all but tasks mentioned above I don't see inductance as being a problem. I understand that DCC works well above 50Hz and inductance would introduce phase shifts as well as increasing the impedance.

(3) From what you say, wiring for point motors should be 8A minimum and take your point regarding sticking switches. With Peco point motors taking 4 amps continuous you might just get away with using 24/0.2 with a continuous rating of 6A as long as the wires were not loomed. (This was dramatically brought home to me when, as a teenager, I used some 5A flex folded back on itself to form a 6 or 8 wire bundle to drive a 2kW fire. When I undid the string holding it all together - pre tywrap days - the whole lot was a solid wadge of insulation. I kept it as a reminder for years. The current flowing through it was 8 amps.) Mind you, how quickly would you no longer have a point motor? Would that burn out first. A while back I deliberately burned out a faulty Marklin point motor. It only took a couple of seconds to do it.

(4) See above. If David had said that he was using DCC I wouldn't even have bothered replying.

I am using 7/02 throughout my Z scale layout. The only exception will be where there is a common cable that could be carrying multiples returns from a number of sources (e.g. the common return buss from the track that could be carrying current from four (unlit) trains in which case I will use 16/0.2). I will also require heavier cable if I go down the route selection system of turnout control just to prevent excess voltage drop.

I hope that shows where I was coming from when I wrote my response above. When I come to build my N scale layout (13' x 12') I will certainly use a heavier wire.

Once again, thank you for your response to my message.

With best wishes,
Chris.
 

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***Hi Pimkib

For the power bus 32/.2 is a good size - big enough for a small layout but not too hard to work with. For droppers, about half that weight would be ideal, but as long as they are shortish - ie less than 300mm, then 7/02 will be OK but its better to go a wee bit heavier if you can. DCC Wiring isn't complicated, just ask whatever you like and we'll help - or, if you like, send me by email (or post on list if you can post images) and it can be marked up for wiring for you.

Richard
 

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Thank you very much Richard. I will take you up on your kind offer when I have settled the layout and seen the instructions which will come with the various items - all are ordered, just awaiting delivery. It seems I am a victom of "stocktaking" with all chosen suppliers so I don't expect any deliveries before next week.

Thanks again, Paddy
 
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