# Looking for some opinions



## mopac (Feb 24, 2011)

My next and final layout is still in the planning stage. I have purchased probably 95% of
what I will need. At least 20 years of purchases for this "dream" layout. Glad I bought my
atlas N/S flex track a long time ago. Layout will be around the walls. 30" deep. Right at
80 feet of layout. Room is 15' by 26'. Where I live the UP double main and the BNSF double
main are within hundreds of feet of each other so I want to loosely duplicate this on my
layout. So that is 2 RRs with 4 mainlines around the layout. Lots of tracks. My questions today are concerning the wiring. I have an 8 amp command station and an 8 amp booster.
My first thought was to power 40' of layout with the CS and power 40' with the booster.
A pm42 with each power unit. The 4 bus wires from each line from the pm42. One for each
main. That should give me 2 amps on each main. Now I am starting to think that will
take a lot of of 12 guage wire I want to use for the bus wires. How about I just run 2 bus
wires. one for each RR. So that would be 1 bus wire for 2 mainlines. That should give me 
4 amps per mainline. I have many athearn BB engines and have started adding decoders.
I think 3 BB engines would be the most I would have on each mainline. I know 8 amps will
weld wheels to the track. Is 4 amps too much or should I keep it to 2 amps per main line.
Is that enough for 3 BBs? Sorry for long post.


----------



## DonR (Oct 18, 2012)

Whoa Nellie.

You've got an awfully large amount of power there.

You say you expect to run 3 locos on each Railroad, 
total of 6 simultaneously. At about .5 amps per loco 8 amps would
run 16 trains simultaneously. And even those would
take less than 8 amps because likely you won't
be running them at full speed. Slower speeds
use less current, so your 8 amp controller alone would be sufficient
to power 6 locos, even sound.

You could use your PM42 to protect four
blocks, one section for each of your 4 mains.

12 gauge seems a bit heavy even for a buss, but it
sure won't do any harm. Just don't wire it into
a circle. Connect your controller feed in the middle
and let the runners dead end. With that much
power you may want to add buffers at the end
of each buss run.

You may want to put your 8 amp booster in storage
for a while.

To get more technical you could profit by checking
in on WiringforDCC. They work with heavy power
DCC layouts.

http://www.wiringfordcc.com/wirefordcc_toc.htm

Don


----------



## Brakeman Jake (Mar 8, 2009)

One eight amps command station and one PM42 is more than you need...a 5 amps CS would do the job just fine.Keep in mind that required power is dictated by the amount of current that trains will need,not the size of the layout.But then,larger layouts can handle more trains.so this is your call.

Electrical problems with model trains generally are caused by either poor connections,sloppy joiners and dirty tracks,often a combination but rarely are caused by wire size.Limiting your sectors (mains) to two amps means you could get away with 18 Ga. wire,providing connections are good,much easier to work with and cheaper.Twelve gauge is overkill and would build in much bigger harnesses too.However,I'd use 16 Ga. for a safer margin in case you may have more than one train on the same main at one time wich "may" occasionally trip the PM42 set for two amps...not a big pain and safe.

I have wired my layout the same way but run N scale,so I know it will work fine.HO draw a little more though.


----------



## mopac (Feb 24, 2011)

I think 12 wire is probably overkill but I was thinking of voltage drop because of long runs.
Probably 20 feet to the left and 20 feet to the right. And that is for each of my power units. Is 2 amps enough for 3 athearn BBs? Is 4 amps to much?


Don. 
The 8 amp units were only 20 some bucks more than the 5 amp units. Those extra 3 amps are the
cheapest amps you will ever buy.


----------



## Brakeman Jake (Mar 8, 2009)

Voltage drop?An 18 Ga. wire can carry over 10 amps. 20 ft. away without a sweat and you could spread the same distance in opposite directions from a single power supply without ever seeing any difference in performance.

Food for thoughts...look at the terminals on the PM42's blue connectors...they can't take much larger wire gauge anyway and I haven't heard of one failing yet for this reason.I bet Digitrax know what they're doing...

Two amps may be a little tight for three old Athearn BBs.I suggest you test first as 2 amps. is good safety but 4 amps will do too.In fact,being lucky,you may operate for years without any protection,it's a "just in case" protection.

BTW,sound equipped loco may need to raise to 4 amps. if running more than one at a time.


----------



## feldon30 (Dec 30, 2012)

Agree with others above. No need for the 12 gauge wrestling match. Go with 14.


----------



## mopac (Feb 24, 2011)

Great info . Thanks. That's exactly what I was asking for. Ok, 12 guage is out and
14 or 16 will be fine. I think I will go with 4 amp mains, and try to be carefull.


Any ideas on this

I have the 2012 power supply and want to run both of my power units off of it. It should not be a problem cause Ken of DJ RR said he runs 3 power units from the 2012. The power units
are 40 layout feet from each other. So I will put the power supply in the middle of them. So
I will have 20' runs to the power units. What would be a good guage for that wire?


----------

