Wire Gauge for DCC on an HO Layout

[kenben]

I've seen and heard many opinions of wire gauge for HO layouts. But what is the most reliable wire gauges for a 8' x 6' DCC HO layout with Peco electro turnouts. Bus wire? Feeder wire? Peco electro turnouts with Tortoise switch motors (about 17 of them)? 

Thanks. 

[peahrens]

A frequent question.

I went by a table in the Kalmbach "The DCC Guide" (ed. 1) that is based on keeping within 1/2 volt drop.  Bus wires for a 2A system, for AWG 12, 14, 16, 18 can be 157', 99', 62' or 39' length, respectively.  For a 5A system (my case) for AWG 12, 14, 16, 18, bus wire lengths can be 63', 40', 25', 16', respectively.  

My HO layout is about 5-1/2' x 9-1/2', comparable to your size.  I chose AWG 16 stranded wire (from Lowes) for my bus wires as none would exceed 25'.  (I have 3 subdistricts from circuit breakers so each section has less than 25' length, including the 2' or upstream of the circuit breakers.) 

I used AWG 22 solid wire (from Jim's Hobby Engineering) for feeders, as I liked the way the end could be bent to cozy up to the rail for soldering.  I used 3M suitcase connectors (with the correct tool) for joining the bus / feeder wires. 

For my 12v Tortoise (20-plus) wiring, I used AWG 24 red/black auto zip / rip paired wire from All Electronics (sold by the foot). 

[BigDaddy]

A question like that is only going to get you more opinions.  I use this as a guide

https://dccwiki.com/Wire_Sizes_and_Spacing

If you put your power supply in the middle, your longest run is only 4' so Paul's suggestion is good enough.  The tortoise should be a separate power supply from the track bus.

[kenben]

Thanks guys. I went with 16 AWG for my buss and 22 AWG for my feededs and probably us the  16 AWG for the turnout motors. And getting the 3M suitcase connectors.

My next challenge is I will need to have two (2) buttons/switches for each turnout motor because my layout has a 2'x3' opening in the center, so I'd need access to control all the turnouts from the center as well as from front the outside of the layout.

[peahrens]

On the dual locations for switching a Tortoise, I'll take a stab.  I have not done that, so others may offer other ideas.  The following presumes you do not want to operate the Tortoise via your DCC throttle.  (I avoided that.)

Normally one would put one "cross-wired" DPDT between the 12v incoming power and each Tortoise.  So when the DPDT is thrown, the polarity to the Tortoise changes and the turnout is thrown.  So, if one used 2 DPDTs in series, either one, when thrown, will cause the polarity TO the Tortoise to switch from the existing polarity, and the turnout will change positon, as desired.

http://www.circuitron.com/index_files/INS/800-6000ins.pdf

But I don't know how well that will fit your pistol concerning visibility of turnout position when looking at the control panel mounted DPDTs.  With one DPDT, it can be mounted on a track schematic, for instance, and the handle position can indicate the turnout position directly.  With 2 series DPDTs, the turnout position is a function of the position of both DPDTs, so looking at one does not tell the tale of turnout position.  You could use LEDs (eg., red & green, or bicolor) to indicate turnout position IF they are powered (in series) by the leads to the Tortoise from the 2nd DPDT; i.e., where the polarity exists that the Tortoise is seeing.   Alternately, you could simply mount realistic model RR red/green LED switch indicator lights at the turnout that are visible from both DPDT locations, using the Tortoise auxiliary contacts.  Or use the Tortoise aux connections to power contol panel(s) LED indicators.  Using the aux contacts for light indicators makes the indicator lights an independent circuit, which requires separate power.  Of course, some of these options get into a fair amount of wires to get the indicators one might desire.

In my case, I installed bi-color LEDs at the control panel DPDTs, wired in series with the DPDT output to the Tortoise.  The Tortoise sees about 10v, as the LED voltage drop is about 2v.

IMG_4565 by Paul Ahrens, on Flickr

 

[carl425]

kenben

probably us the 16 AWG for the turnout motors

That's way overkill for the Tortoise.  24 - 28 AWG works fine since they draw such low current.  You want different colors anyway so you can tell Tortoise wires from feeders easily.

[kenben]

Yeah, 16 AWG was an overkill. I ment 22 AWG, but 24 or 28 AWG is even better.

THX

[richhotrain]

I use 28 gauge wire for Tortoises. That is sufficient.

Rich