Layout wire size and route choice of wiring

[NittenDormer]

Two wiring questions that confuse me.

 

My layout is 00 gauge. It is non-DCC.

 

It is approx. 18 feet long x 4.5 feet deep.

 

The separate boards are laid out as per the diagram below.

 

1. What would be a suitable size of wire for a layout of this size? I’ve read various stuff referring to ‘big’ layouts and ‘long’ wiring runs, without any clear definition of ‘big’ or ‘long’. As for ‘voltage drop’… I’ve got 16/0.2 and 7/0.2 equipment wire. Which would be better? Do track feeds and point motors have different requirements? Can I mix the two without impact?

 

2. Which would be a better way or running my wiring (basically, track feeds and point motor feeds)?

Option A is looping it around in a circle following the track loop.

 

Option B is having each baseboard connected separately to the control panel.

 

Either way, they are likely to have 15-pin male/female connectors.

 

NB please show your working out (i.e. explain the reasoning behind your preference). Also, please don’t decide on the basis of imperial/metric!

 

 

Scan0009.pdf

Edited November 24, 2018 by NittenDormer

[Miss Prism]

I can squeeze 16/0.2 wires into the ferrules of a D-type plug/socket, so that it what I prefer, and what I would recommend for general board wiring. (I use 24SWG TCW droppers from that underboard wiring to the rails themselves.) Short spurs off the main feed wiring from e.g. a point motor switch to a local turnout vee can use 7/0.2 with impunity. If you're using heavy-duty uncouplers for AJ magnets, then 16/0.2 is recommended.

 

Regarding your architectural choice, your option A (the 'ring main') makes slightly more sense electrically, but has the disadvantage that the whole layout has to be up and connected for things to work or be tested. The 'star' system (your option B) doesn't have that limitation, but is likely to involve more cores coming from your control panel. The choice does depend on the actual track plan and the other electrical things (signals and turnouts etc) you have.

[Suzie]

Hi Nitten

 

I would favour going with star connected to save having to route a lot of circuits through the front boards making the connectors a lot larger than they need to be. It will make fault finding a lot easier and you may be able to get away with 15-pin 'D' connectors, but I suspect in practice some will need to be 25-pin or perhaps 37-pin.

 

That said there are circumstances that will make the ring connected system preferable, or possibly a hybrid system with smaller stars (is that 'snowflake' topology?) if there are a lot of connections going between baseboards which can be a feature of DC wiring when local power routing is used.

 

I would use 16/02 wire for your track feeds. A 9' run is not long in layout terms. It would not be sufficient for DCC but I am assuming that you have no plans to upgrade at any time in the future.

 

You have not specified which point motors you are using. High current solenoids such as SEEP or standard Peco PL10 will need big wire like 32/02. When going through the 'D' connectors they will need to split to two 16/02 wires and use two pins on the 'D'. Low power solenoids like PL10W will be OK with 16/02. If using a common wire for solenoids make sure that you only fire one at a time or there will be excessive losses in the common wire.

 

Servos will be OK with 16/02 for the red and black wires with 7/02 suitable for the signal wire.

 

Stall motors and end cutoff motors should be OK with 7/02 wire.

[Crosland]

You don't say how you want to operate the layout, but any but the very simplest DC layout will need to be split into sections with individual feeds from the  switches on the control panel. Also, it's not DCC, so any talk of ring mains is probably inappropriate.

[LongRail]

Feed goes to toes of points so,that the power is switched along with rather point blade

[BR60103]

I would probably follow the track along the near side but cross the layout and folow the track on the far side. It might also depend on where the complexities are on the end tables.

My long bits of layout wring are what we call lamp cord as it is easily and cheaply obtained at local hardware stores. It is massive overkill for the amperage (10-15 amps) but available in a hurry when needed. Smaller wire for going to the rails.

[Junctionmad]

I would probably follow the track along the near side but cross the layout and folow the track on the far side. It might also depend on where the complexities are on the end tables.

My long bits of layout wring are what we call lamp cord as it is easily and cheaply obtained at local hardware stores. It is massive overkill for the amperage (10-15 amps) but available in a hurry when needed. Smaller wire for going to the rails.

Lamp cord is typically 1mm2 twin flexible , wire bought in Diy stores is always way more expensive then buying rolls of proper cable from an electronics supplier.

 

The other source of good cable is car electrics dustributors , you can often get reduced insulation cable there , as normal hook up wire has insulation ratings and hence thickness way beyond what we need. Car loom wiring has lower insulation ratings and thinner jackets and often is more cost effective , especially in higher diameters

 

Dave

[Ian Morgan]

With reasonable size wire, the connectors will probably cause the most voltage drop, so 'daisy-chaining' across boards requiring 6 or 8 connectors along the run can give a noticeable drop of voltage. By connecting in 'star' formation, each wire run will only have a single connector (or one at each end), so should impose less of a voltage drop, and also result in better reliability.

 

You don't say if you will operate points by servos, 'stall' type motors or old-fashioned solenoids. The wiring requirements for these will depend on your choice.

[DCB]

A couple of tricks I use on a DC layout.  1 The control panel on the indoor terminus is loose,  the switches are rotary switches and poke through the baseboard framing so they can be pushed back to allow soldering etc.  2 Wiring runs as far as possible through trunking, either long runs or just short lengths or have hardboard sheets attached to the bottom of the baseboard under the wiring.  3 points.   The wires go to the outer rails on the points, that is the same as saying they are fed from the toe but by feeding the buffer stop end I have saved ten feet of wiring. Only do this if you understand what I am saying.

[LongRail]

David,

 

I don’t understand what you would want to generally feed the buffer stop ends of the points on a DC layout as you don’t get the isolation from the points

[jpendle]

I think what is m===

 

David,

I don’t understand what you would want to generally feed the buffer stop ends of the points on a DC layout as you don’t get the isolation from the points

 

David said he wires to the OUTER RAILS of the points, topographically and electrically this is the same as wiring the TOE end.

 

Now if you were to wire the inner rails of the points this way fun would ensue.

 

Regards,

 

John P

[Junctionmad]

A couple of tricks I use on a DC layout.  1 The control panel on the indoor terminus is loose,  the switches are rotary switches and poke through the baseboard framing so they can be pushed back to allow soldering etc.  2 Wiring runs as far as possible through trunking, either long runs or just short lengths or have hardboard sheets attached to the bottom of the baseboard under the wiring.  3 points.   The wires go to the outer rails on the points, that is the same as saying they are fed from the toe but by feeding the buffer stop end I have saved ten feet of wiring. Only do this if you understand what I am saying.

I don’t really see any advantages in this approach

 

Running wiring through trunking or worse still hiding it all be behind hardboard “ cosmetic “ sheets makes debugging or fixing anything a right PITA , far better to group wires by destination item , or function and constrain them simply using methods that allow you to unbundle selectively if needed

 

Wiring the buffer stop end essentially is the same as wiring the toe , but inherently relies on rail joiners to feed the associated point , it only saves wire if the wiring topology and the track layout lend itself to that approach

 

Dave

[NittenDormer]

Have just bought my first point motor (gauge master seep). 1 point motor reuquires 3 wires from control panel, 2 motors means 5 wires... Seems like just too many to wander around 3 boards beforehand, so current thinking is the star formation.

[Junctionmad]

Two wiring questions that confuse me.

 

My layout is 00 gauge. It is non-DCC.

 

It is approx. 18 feet long x 4.5 feet deep.

 

The separate boards are laid out as per the diagram below.

 

1. What would be a suitable size of wire for a layout of this size? I’ve read various stuff referring to ‘big’ layouts and ‘long’ wiring runs, without any clear definition of ‘big’ or ‘long’. As for ‘voltage drop’… I’ve got 16/0.2 and 7/0.2 equipment wire. Which would be better? Do track feeds and point motors have different requirements? Can I mix the two without impact?

 

2. Which would be a better way or running my wiring (basically, track feeds and point motor feeds)?

Option A is looping it around in a circle following the track loop.

 

Option B is having each baseboard connected separately to the control panel.

 

Either way, they are likely to have 15-pin male/female connectors.

 

NB please show your working out (i.e. explain the reasoning behind your preference). Also, please don’t decide on the basis of imperial/metric!

 

Scan0004.jpg

There is no advantage shadowing the track with track cable , depending on where you want track connections , optimize the wiring runs , to achieve the minimal length from power source to consumption point, consistent with your connector strategy ( ie if you have one baseboard to baseboard connector then wires will congregate at these points.

 

For OO you can get away with short ( <3 meters ) of 7/0.2 but it’s borderline after this and 16 strand is better , personally I’d run 1mm2 dc feeds to each baseboard and tap off with 7strand , but this is very much a function of how much section switching you envisage. doing

 

If you have significant section switching , meaning you are running multiple feeds from your control panel to track sections via control panel switches , then it may be entirely practical to wire with 7 strand , given it’s likely only one engine will be powered up in any section

 

On a recent club layout , approx 12 feet by 4 feet , all the wiring was 7 strand

 

Dave

[O-Gauge-Phil]

You were asking about the formula, this is:-

 

Volt drop = current x length x factor

For 1mm copper it’s 47mV per amp per metre.

 

So if your longest run is 7 metres and your locos draw 500 mA then the volt drop is 0.5 x 7 x 47 = 164 mV. You’ll probably lose about 2 volts across pickups and commutator, therefore 0.75 or 1 mm2 is going to be good. Or if you have something to hand and the price is good and it won’t be mistaken for mains cabling then that’s good, generally the bigger the better.

 

When you’re looking for connectors try to get gold plated, they are meant for low analog voltages, for digital circuits the drop across a connector is not a factor.

 

DCC is slightly different.

 

If you have servos keep your wiring well away from this or cross at 90 degrees.

 

Phil