Maximum cable run - Massoth Central Station

the center conductor of RG9 is .0855", 12 gauge solid wire is normally .0808, so it'e even bigger than 12 gauge.

The center conductor is also silver plated, great. Shielding is not really what you want in DCC, common mode rejection is.. (twists)

RG9 costs about a dollar a foot here if you buy 1,000 feet. It's 50 ohm, so it should be fine. It would definitely handle the current.

Greg
 
Probably a bit late now but I have a big layout with 3 DCC power sections. In two sections the feeds are close to control box. The third one is fed about 25+meters (28yds) from the booster to the track feed. I used 2.5mm copper cable for this thinking it would be adequate. It is not. There is a significant slowing down of the trains as they enter the new section. I discussed this with a friend who knows about these things and he told be he is not surprised. We are running 24 volts (give or take). Apparently using 2.5mm cable is not adequate to run from the front to the back of the trailer of a big artic truck as the voltage drop is too high. Oh well will be rewiring with 5mm cable (which he suggested) next year. I will report back.
 
When you say 2.5 mm cable, you mean 2.5 mm squared, i.e. the cross sectional area, or do you mean the copper wire is actually 2.5 mm in diameter (without insulation)?

From reading, the standard is in square millimeters area, which equates to 13 gauge wire... I use 10 gauge wire for shorter runs.. (lower number larger wire)

2.5mm wire is 6.8 ohms per kilometer, so 0.0068 ohms per meter times 25 meters = 0.17 ohms, so at 10 amps you would lose a little under 2 volts. That is actually noticeable. I've noticed big differences in top speeds with just a few volts drop.

I went from an NCE system to a Zimo system because the NCE only put out 20 volts, and I can get the full 24 from the Zimo. One loco went from a scale 65 mph, to 90 mph from 20 volts to 23 volts... a huge difference.

(this was a passenger train, which I run close to 75 mph some times)

So, if you have enough current load, I'd go to at least 4.0 mm wire... that's still under what I am running no more than 40-50 feet. My wire would be close to 5.0 mm wire... If I was over there, I'd guess I would have to use 6 mm wire.

Greg
 
Greg Elmassian said:
2.5mm wire is 6.8 ohms per kilometer, so 0.0068 ohms per meter times 25 meters = 0.17 ohms, so at 10 amps you would lose a little under 2 volts. That is actually noticeable. I've noticed big differences in top speeds with just a few volts drop.
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That's an interesting calc, Greg.

I am the President for Life, Chairman, Treasurer, Secretary and sole member of the cooker cable club. When I was getting ready to lay my first garden railroad, I wanted to put a jumper cable half way round (bisecting the circle) and asked a friend (qualified electrically) to calculate what I'd need to avoid voltage drop. I suspect that he provided me the answer from readily available domestic cable sizes, which this side of the pond jump from 2.5mm2 to 6.5mm2 - which is cooker cable.

A number of people pooh-poohed the idea, and one was frantically against it on spurious safety grounds ( he was worried about a subsequent occupier of the house trying to connect a cooker to it o_O ) but I have repeated the practice on my current railroad.

So, while the cooker cable may be over the top - although you certainly won't see a voltage drop - the principle is a good'un >:)>:)

Being a simple person, I worked out that if a bisected the circuit with a jumper cable that produced the full operating voltage half way round, then the track joints have only got to provide good continuity for a quarter of the circle before they meet the stuff coming the other way :nod::nod::nod:

So, on my 300 ft of track, the fishplates only have to provide good continuity for 75ft, and as about half the track is 1m flexi lengths (bought second hand) then that's only about 50 joints with about one third being rail clamps - which gives OK track power continuity.

The cooker cable club is always open to new members :cool::cool:
 
I must be lucky because I now and on my previous layout used approx 1 mm dia multi wire cable with no problems of voltage loss. The layout is sectioned up with feeds to both ends of of each section on the largely end to end layout. Longest cable run is 30ft and 80ft(approx) for the doubled connections. I split the cable at the first (closest) section feed to give the feed for the other end. Each section has a switch for fault finding. Not that I have had any since laying out or when some nutmeg plonks a Metal Item touching both rails! Usually a Simplifier Clipboard with a Metal Paper Holder!
 
Also worth noting:
If you are running DCC, then the 'signal' and 'power' are the same thing, and something called 'skin-effect' starts to come into play.. - This basically says that if you have a 'RF' (DCC) signal, it will tend to travel along the outside of the conductor..

So if you can find a cable with the same overall size of conductor (6.5mm squared), but with many strands, then this will be 'better' for the job. :nerd::nod:
 
PhilP said:
Also worth noting:
If you are running DCC, then the 'signal' and 'power' are the same thing, and something called 'skin-effect' starts to come into play.. - This basically says that if you have a 'RF' (DCC) signal, it will tend to travel along the outside of the conductor..

So if you can find a cable with the same overall size of conductor (6.5mm squared), but with many strands, then this will be 'better' for the job. :nerd::nod:
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Aha I can see math comming into effect here with PieR Squared and measuring small 10 thou cables plus counting how many there are plus making sure that none are broken on wire stripping at other joints. Seriously guys I think we are over complicating stuff a little. Though what Phil says is sound.
 
dunnyrail said:
Aha I can see math comming into effect here with PieR Squared and measuring small 10 thou cables plus counting how many there are plus making sure that none are broken on wire stripping at other joints. Seriously guys I think we are over complicating stuff a little. Though what Phil says is sound.
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Nah - the caveat is 'if you can find' :nod:

I remain the President for Life, Chairman, Treasurer, Secretary and sole member of the cooker cable club. Remember we're talking of preventing voltage drop over distances around 70 - 100 ft.

The membership list remains open :nerd::nerd::nerd::nerd:
 
Yes, PhilP, very true, and there's some other even more interesting side-effects to the skin effect.

One is that stainless steel rail is a better conductor for DCC than brass or aluminum rail... now no one will believe this until it is explained.

I always was "taking a hit" from people because they reminded me that the SS rail would need more feeders and have greater voltage drop... but the weird thing is that when I changed over from brass to SS, I swear it worked better.

Reading up on the skin effect the other day (since I wanted to confirm that there was noticable skin effect at DCC frequencies), I figured out this tid-bit... I leave this as a teaser for others to discover for a bit. Now I understand why it works so well for me, and I have no "noise" issues, no terminators/snubbers, but 850 foot that all works well.

Greg
 
I have heard it say amongst the older guys that were into 3 Rail and Stud Contact with both 0 and Gauge 1 that Steel Rail is the better of all metals for conducting. Of course they were looking at two steel rails for return current and more often or not were indoors. Of course one has to accept the Rusting Effect of Steel and the work to keep clean outside hence I can well beleive that Stainless Steel will perform better than Brass or Nickel Silver Rails.
 
I am pleased to report that a 50 meter run has not seemed to cause any problems at all. I have used heavy duty 240vac extension cord.

POM and all communications do not appear to be affected.

The most I have ever been able to draw at once is 4 amps with four trains (sound and smoke) running at once so that is a far as I have stretched it with this.
 
I seem to remember (from about half-a-century ago) that voltage drop on cables was called Potential Difference - or was it Drop? The days of 3029 and upwards.
 
Slawman said:
I am pleased to report that a 50 meter run has not seemed to cause any problems at all. I have used heavy duty 240vac extension cord.

POM and all communications do not appear to be affected.

The most I have ever been able to draw at once is 4 amps with four trains (sound and smoke) running at once so that is a far as I have stretched it with this.
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Yea, while being multi strand - and benefiting DCC as above - it all depends on the size of cable. Heavy duty suggests at least 2.5mm2. Sheathing will be better, but for garden use it's probably best laid in conduit unless, like my original layout, you bury it under the trackbed.
 
For my layout wiring, I bought (several years ago) two reels of very heavy-duty speaker cable (twin stranded cores) from the now-departed Maplins; three runs of this were laid under the chippings that form the trackbed, to feed the ground-level loop at three roughly even-spaced locations. Where the trackbed comes within four feet or so of the Conservatory, the three cable runs were routed through some buried conduit under the block pavers, then led through the Conservatory base brick wall via a short vertical conduit - inside the Conservatory the three cables exit from the wall and are connected together via a very large choc-block connector housed in a Rapid project box, from which a single set of the cable leads to the green plug for the Massoth 1200Z.

The wiring was all put in a good 2-3 years ago, but has only been finally connected up in the last few weeks now that I've finally got a running loop of track down, and it doesn't seem to have suffered any ill effects in that time - it's certainly all working well now!

Jon.
 
Zerogee said:
For my layout wiring, I bought (several years ago) two reels of very heavy-duty speaker cable (twin stranded cores) from the now-departed Maplins; three runs of this were laid under the chippings that form the trackbed, to feed the ground-level loop at three roughly even-spaced locations. Where the trackbed comes within four feet or so of the Conservatory, the three cable runs were routed through some buried conduit under the block pavers, then led through the Conservatory base brick wall via a short vertical conduit - inside the Conservatory the three cables exit from the wall and are connected together via a very large choc-block connector housed in a Rapid project box, from which a single set of the cable leads to the green plug for the Massoth 1200Z.

The wiring was all put in a good 2-3 years ago, but has only been finally connected up in the last few weeks now that I've finally got a running loop of track down, and it doesn't seem to have suffered any ill effects in that time - it's certainly all working well now!

Jon.
Click to expand...
Yes, it's all in the planning :nod::nod:

I was two days away from the turf delivery when I remembered my intention to lay the cooker cable - a quick dash to Q&B to purchase some 20mm conduit and a length of my son's best dyneema (don't let anyone cut that length :punch::punch: ) and I quickly dug a trench across the garden, backfilled and rolled before I laid the turf :whew::whew::whew::whew::whew:

I managed to draw the 6.5mm2 cable without any problems some time later >:)>:)
 
This subject comes up quite often, it comes up at least once a year since I have been in the hobby on every forum.

Some people go on about the absolute smallest (cheapest) wire that can be used. Some over engineer it a bit larger than worst case. Some people hit it pretty close.

Years later, the people who designed for 10 amps or over engineered it are happy, the under-sized wire people have issues, re-laid wire or gone to battery.

Your track, and if track powered, your power distribution system is the foundation of your layout, if it does not work well, nothing will work well.

Greg
 
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