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drop leads

Started by SteamGene, July 02, 2007, 09:05:41 AM

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SteamGene

I'm using 18 gauge wire for my drops.  How long can they be?  Here's the situation - the sceniced portion on the west penninsula is over and a bit (2") to the west of the reverse loop lead.  The elevation averages about ten inches.  Can I run leads to both tracks from one buss without sustaining too much drop in current?  If I can drop leads from the one buss, it saves running one buss line.  The reverse loop itself already has its own separate buss. 
Gene
Chief Brass Hat
Virginia Tidewater and Piedmont Railroad
"Only coal fired steam locomotives"

Bojangle

#1
Gene:
What is your maximum current draw and the maximum run?  That would determine the voltage drop for a particular length of run.  I have voltage drop charts for 12 and 24 volts circuits.  A voltage drop of 1-2% is acceptable. 

http://www.currentsolutions.com/knowledge/vdrop.htm

Calculators aren't exact, but gives you a rough idea.
Bo

r.cprmier

Gene;
If you are talking DCC, you are also talking  18VAC or so, and a 6' or less pigtail (drop) shouldn't create major havoc.  BTW; use stranded wire for better results; my choice of weapon is #18 THWN stranded.   I do NOT use solid wire on my layout.

RIch

Rich

NEW YORK NEW HAVEN & HARTFORD RR. CO.
-GONE, BUT NOT FORGOTTEN!

SteamGene

It will work, then.  I hae both solid and stranded so far.  Which wire is another "It's my way so the right way," it would appear.  I had a friend who is well established in DCC see my Atlas 18 gauge and turned up his nose at the idea of stranded wire.

Gene
Chief Brass Hat
Virginia Tidewater and Piedmont Railroad
"Only coal fired steam locomotives"

duker1

Good website that you offered Bo!

Duke....

r.cprmier

Gene;

Ok;  There is some credibility to what you say.  My thoughts are based on my years and knowledge of my trade.  As a practice, both 16 and 18 will work-there is negligible difference at that six-foot length; one might be attempting to make a mountain out of a molehill.   If someone has a better idea, wonderful.  What I go by has worked like gangbusters for a long time; so, to quote; I'll stick with a winner.  Solid or stranded:  it is your call.  Don't forget; your buss wire is (should be) heavier-like #12 THHN-again, solid or stranded-your bag.

Rich

PS:  there are idiots who will use phone wire to conduct power type circuits.  You do not strike me as one of them...
Rich

NEW YORK NEW HAVEN & HARTFORD RR. CO.
-GONE, BUT NOT FORGOTTEN!

SteamGene

Then buss wire is #14, mostly solid.  I've had three people who know electricity look at it and not a one has said "It's too thin."  So I hope.
Gene
Chief Brass Hat
Virginia Tidewater and Piedmont Railroad
"Only coal fired steam locomotives"

Bojangle

Duke:
Thanks.  It's not a perfect calculator, but gets you in the ball park.  For those who want more specific "circular mil and resistance" there is a link, and you can fine tune your own values.
The 14 awg will provide acceptable voltage drops for 2, possibly 3 locos. 
My biggest concern is always adequate over current protection  in case of shorts.  Without it, 5 amp boosters can provide some extra smoke for atmosphere lol
Gene:  Get 'er done, wanna see it run.
Bo

r.cprmier

Gene and Bo;

Yep; the number 14 will work.  For my money, I will take #12.  The difference for this application is hardly any, the ampacity and reslutant peace of mind more than make up for any.  BTW, stranded wire has something going for it in an AC application:  first, current travels on the outer surface of it-each strand actually-and also that solid isn't as flexible as stranded, and can break when stranded might not.

The bottom line is still each person's call.  I have always said, it is your money, and your railroad.  You should do as you see fit.  Gene, I go with Bo...Get 'er done!

Have a good-and safe-Fourth of July all!!!!!


Rich
Rich

NEW YORK NEW HAVEN & HARTFORD RR. CO.
-GONE, BUT NOT FORGOTTEN!

SteamGene

did you notice that Tony Koesler says to lay track in the winter, not summer?  ;D  Actually, what's holding me up right now are the new kitchen cabinets resting on the patio, almost blocking the door to the train barn. 
Gene
Chief Brass Hat
Virginia Tidewater and Piedmont Railroad
"Only coal fired steam locomotives"

Craig

I'm with Rich. Stranded wire has a higher load rating so it is the logical choice. But then not everyone has a mobile THHN dispenser in their driveway.

Craig

Bojangle

Here is another good link:

http://www.rowand.net/Shop/Tech/WireCapacityChart.htm

Note the "Solid vs Stranded" 

Bo

r.cprmier

Craig;
If  you are not aware of it, THHN, THWN THNN TW etc, are insulating types, and are suitable in varying situations, some best for this or that, others differ, that is what that is about; application.  Stranded wire is jacketed with any of the abovementioned and solid can be as well.  The insulating capacity of most of the above, is rated at 105 degrees c., so actually, any insulator composition would be suitable for our use.

As I said before, my money goes with #12THHN.  It is relatively cheap, works well, takes suitcase connectors, and is more than adequate for several engine operations at a time, considering that it is generally rated for 20amp circuits, 600VAC max; though Art. 310, NEC, has some other applications, and varying ampacities; but that is pretty much beyond the scope here.

As far as availability, you can find TW type insulated wire at any electrical supply house.  In Ct, and Mass, try Electrical WHolesalers, Graybar, Eastern, etc. New York, try Kennedy or Swift Electric Sy if you live in Westchester, Dutchess, or Putnam county.  Without digging out invoices, I believe a 500-foot roll generally goes for in the neighborhood of about 35.00.  Not bad, considering what the other operations are hooking you for in lesser quantities.

RIch
Rich

NEW YORK NEW HAVEN & HARTFORD RR. CO.
-GONE, BUT NOT FORGOTTEN!

Craig

Rich,

I'm well aware. I was an electrician, once upon a time. I was thinking that if you are an electrician you probably have a van full of THHN in your driveway, thus my remark.

Craig

r.cprmier

Craig;
OK, Gotcha, Man.  A lot of laymen are under the impression that the insulation lettering designation has something to do with the wire properties.  I thought you might be a layman.

I do use a lot of THN" type insulated wire, as most of my work is commercial/industrial.  In the van are chiefly three sizes; #12, #10, and #14 gauge, stranded.  I find that #16 works well in this hobby in a variety of applications, and I don't carry a lot of it in the truck.

I re-read your original reply to me, and caught the "mobile" thing and got a good laugh out of it.

Hey, I am going out to plant some more pachysandra.  Have a great fourth, all.

Rich
Rich

NEW YORK NEW HAVEN & HARTFORD RR. CO.
-GONE, BUT NOT FORGOTTEN!