# Basic wiring question



## Walman (Dec 18, 2011)

See the attached drawing of my layout. During my planning I had assumed that for my bus wire I would create a loop that basically followed my mainline around the layout (not shown for simplicity but basically a single-track dogbone along the outside circling the layout). But now that it is time to start wiring I think that just complicates this not overly large layout. 

So I'm thinking of just running a "T" of bus wire down the middle of this layout as shown. As you can see I have a Superchief DCC so will have the DCS100 command station and UR92 duplex receiver as part of the main system. I will wire a Digitrax PM42 to manage my power districts and handle reversing duties. I'll eventually add a BDL168 for block detection. I'll drop my feeder wires and run to the bus at 5 foot intervals and on each side of my insulfrog switches.

So any reason I can't wire as shown? What am I missing?

Thank you,

Walman


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## mopac (Feb 24, 2011)

Ok first, let me say I have not wired anything more than a 4x8 layout. So I am
just asking. I will be doing a large layout soon. You have 1 pm42. 4 districts from
that. You have reverse loops at each end of layout. Do you run a seperate bus
to each loop from the pm42? That leaves 2 districts. One for left part of mainline
and one for the right side of layout main. Make any sense?


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## Walman (Dec 18, 2011)

mopac said:


> Ok first, let me say I have not wired anything more than a 4x8 layout. So I am
> just asking. I will be doing a large layout soon. You have 1 pm42. 4 districts from
> that. You have reverse loops at each end of layout. Do you run a seperate bus
> to each loop from the pm42? That leaves 2 districts. One for left part of mainline
> and one for the right side of layout main. Make any sense?


Well let me say upfront you are a 4 X 8 layout ahead of me  I've never wired anything so I may be wrong but a plain loop itself will not create a reversing situation (inner and outer rails are always inner and outer right?) so in the strictest since I don't believe that would present a problem. Am I wrong about that?

I've attached a poorly drawn picture of my actual track plan where red = mainline and green = industry/sidings. I've circled in black where I believe I will need isolation between the mainline and industry lines. Basically anywhere that they touch I will isolate. I do have the one reversing section of mainline track and show it isolated as well. Since this is a single piece of track with no switches or other connections my thought is I will isolate it as shown and wire it with an Digitrax AR1 autoreversing unit. Someone please tell me if this is unneeded, won't work, better way to do it, etc..

So regarding power districts I planned on breaking the layout in half (forgot to show that). I'd have one mainline power district and one industry/siding power district for each half of the layout. Technically the one small section of mainline reversal track mentioned above will technically be a 5th district but not run by the PM42. When I expand in the future I'd add another PM42. 

So any/all please jump in and tell me if I am missing the mark anywhere.

Walman


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## mopac (Feb 24, 2011)

No, those turns at the ends will not cause a reversing situation. I thought you had a single track with real loops at the ends.


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## DonR (Oct 18, 2012)

Walman

Yes, your reversing unit will be needed. Think I pointed out
in another thread a choice of where to isolate it. There are
two possibilities. If the length of the of the red track that angles 
across and creates a reverse loop is only a couple of feet, it should
not be the isolated section. Instead make the whole
lower loop isolated. Put your insulated joiners just above the turnout on the right side,
and just below the opposing turnout on the left side. You would also
need to use them on that connecting track just after the turnout on
the left side as it will become part of the reverse loop isolated section.

If that angle track is a train length long it would be more simple to use
it as your isolated section and only need insulated joiners in both rails
at both ends of it where the rails connect to the turnouts.

Don


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## Walman (Dec 18, 2011)

DonR said:


> Walman
> 
> Yes, your reversing unit will be needed. Think I pointed out
> in another thread a choice of where to isolate it. There are
> ...


Thank you Don yes I printed your original note and put it in my reference folder thank you. That angled red mainline is just short of 3 feet. During normal operations for realism's sake I don't envision having any train longer than that due to spacing of my industries and such. However, the area adjacent to the train area is going to become our family room (moving from upstairs). I can envision evenings where we are not playing with the trains but I place an extra long train on the tracks and have it run along the mainline for the sheer joy of just watching it go around. 

So based on that does it change your opinion on best placement? 

Over-thinking as always,

Walman


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## DonR (Oct 18, 2012)

That 3 foot section could work. However, I feel more comfortable with
the longer loop section...or even an isolated section of it. Mind you, tho,
that the angle red track that actually creates the reverse loop would
have to be part of the isolated reverse loop track but you would not need
to go all the way around. There is no reason not to tho. unless you are using
that angle track, the polarity of the large loop will stay the same as the 
rest of the layout. You can let your trains run continually over it and
the reverse controller will remain quiet. It only operates when it 'sees'
a momentary 'short circuit' as the loco crosses the border between the
main line power and the reverse loop power. At that point it does a very
fast polarity reverse in the reverse loop track.

Don


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