selector12 gauge is good for 20 amps continuous, more than enough to run your railroad.
12 gauge is good for 20 amps continuous, more than enough to run your railroad.
As Martin states above, this fact is irrelevant when it comes to whether the wire is sufficient for DCC bus wiring. The determination of whether the wire is "safe" is based on the heat generated in the wire. The fact that you won't burn the house down does not mean that you won't have sufficient voltage loss to cause trouble with the DCC signal, or that that the resistance of the circuit will not be great enough to defeat the short circuit detection of the booster.
It's all about voltage loss. A loss of 2V in a 110V circuit isn't going to bother anyone, a loss of 2V to the rails might well bring your system to it's knees. It's true that most of the rules of thumb are pretty conservative, but it's a lot easier to be conservative at the beginning than redo things later. And it allows for the fact that there are little bits of resistance in our circuits that we tend to ignore, going through connectors, rails to wheels, etc.
Jeff But it's a dry heat!
That buzzing sound is the sound of wheels being welded to rail. A 1.5mm2 wire that's 10m long will not allow the booster to see the short and trip correctly. That's why it works with a shorter piece of the same wire. Same principle applies to a large bus and small feeders. Make the bus large and include frequent small diameter feeders.
2.5mm2 wire is just a bit smaller than 12awg. That size should be fine for your bus. Doesn't matter for DCC if the cable will safely carry 20, 30, or more amps at 110VAC. There should be no more than 1 to 1.5 volts drop and the booster's short circuit protection should trip immediately when shorted at the farthest point electrically from it. I always tell people to start counting as you short the rails. If you get to two before the booster trips, add feeders or a larger bus.
In testing wire size for NTRAK, we found that 12awg wire would handle an 80 foot (one way) run reliably. Remember though that the actual length is out and back - 160 feet.
Here's a link to a table for wire size and current limits. There's a handy voltage drop calculator at the bottom.
Martin Myers
Stevert What standards for gauge numbers are you referring to when you say "2,5 mm(10 gauge) and "4mm (6 gauge)"? Those aren't AWG sizes, are they? The reason I'm asking is that on the chart I referenced before, those sizes don't align. AWG 10 is much larger than 2.5mm2. It's actually between 4mm2 and 6mm2. Yes, that's pretty big. You should be okay using the 2.5mm2. Steve
What standards for gauge numbers are you referring to when you say "2,5 mm(10 gauge) and "4mm (6 gauge)"? Those aren't AWG sizes, are they?
The reason I'm asking is that on the chart I referenced before, those sizes don't align.
AWG 10 is much larger than 2.5mm2. It's actually between 4mm2 and 6mm2. Yes, that's pretty big.
You should be okay using the 2.5mm2.
Steve
It was just me being really really stupid. ;)
I looked at another chart I goggles but made the mistake by looking at the diameter instead of the mm2. Sorry, me bad. :)
I'll get some 2,5 mm2 cable. I rad a recomendation somewhere to use stereo cables. They are decently priced and come in the 2,5 mm2 dimensions.
Once again, thanks for your help and setting me straight about the AWG.
Magnus
LillenThanks all of you for your help. Do you think I can use the 2,5 mm(10 gauge) and get away with it? Their is a rather substantial price difference between that and 4mm (6 gauge) that unless it's necessary would like to get away from. Magnus
Thanks all of you for your help.
Do you think I can use the 2,5 mm(10 gauge) and get away with it? Their is a rather substantial price difference between that and 4mm (6 gauge) that unless it's necessary would like to get away from.
Marcus,
Magnus, 10 gauge is more than sufficient for your purposes. 10 gauge is good for 30 amps continuous service. You only need that gauge for running heavy draw appliances like a kitchen stove. 12 gauge is good for 20 amps continuous, more than enough to run your railroad.
If you are concerned about shorts detection, perhaps you need to re-configure your electrical distribution under your layout. You might benefit, for example, from having a sub-bus of the same 12 gauge wire, and then having your lighter gauge feeders rise up to the rails from the sub. You run an appropriate bus length, and then rise up to two or more subs of appropriate lengths. From the subs, still robust 12 gauge wire, you feed the rails with anything short and light, such as 22 gauge wire as long as 50 cm.
-Crandell
I have an NCE PowerPro 5 Amp system on my HO scale home layout, and we use the same system with four extra boosters on a large HO scale club layout.
For extra protection, I added Power Shield circuit breakers from Tony's Train Exchange to every booster at the club, but the automatic circuit breaker within the PowerPro should be sufficient protection for a home layout. And 5 Amps will NOT cause damage to anything because of the internal circuit protection within the PowerPro, which is extremely fast-acting.
Magnus,
Many folks in the U.S. use 14 gauge or even 12 gauge bus wiring (with AWG, a smaller number is larger wire).
I found a comparison table here, and in metric, it would appear that 2.5mm2 or possibly 4mm2 would be correct for your situation.
You sometimes need to go up a size for long runs or higher currents, and since you seem to be considering some longer bus lengths I'd seriously consider using 4mm2.
I'd also make sure I have plenty of feeders, with one set for every meter or so of track. You should be able to lay a coin across the rails (in the U.S. we use a quarter for HO-scale track) anywhere on the layout and have the booster immediately shut down, with no buzzing at the rails.
HTH, Steve
Hi,
Thanks for the positive and helpful reply. In my manual their is no such info on page 22 though. Might be different printings. On page 14 it mentions that the status light should indicate something but mine is solid red all the time.
The track light do shine consistently and that doesn't change during a short either.
The reason I'm worried is that I do believe the sound of electricity passing through the short rather then having been cut of. Maybe I'm just worried unnecessarily.
With 5 amps you are going to fry something. If it doesn't trip, the buss wires may be too thin. Five amps needs power districts with their own circuit breakers. Others on the forum can give details. My little power cab doesn't need power districts.
Good luck.
Lee
Your system is operating properly. It has recognized the short and shut down the system. This is evident by the loco sound shutting off. The status light should flash a slow steady flash when there is a short circuit (see page 22 of the you manual). The NCE PHP does not have a buzzer to indicate when there is a short. Some checking on the web will turn up a simple ciruit that you can build to to give an audio signal of a short. The PHP will automatically reset itself once the short is removed. There is no need to restart the system by pressing a button.
Yesterday I got my new NCE DCC system, 5 amps, Power Pro. Now I have a problem, maybe?
I can't make it short! A engine stalled at one of my turnouts. It stopped and the sound went off. But as soon as I removed it the system was back on. All I heard was a buzzing sound from the track where the short was. Is this normal. On my previous system, a Roco system, I had to relieve the short by pressing a button after I removed the cause of the short. But I get no signal what so ever. There is no indication of the short besides that the engine doesn't make a sound and that their is a low buzzing sound.
I have used the penny trick and other metal objects and while it do shorts so that no engine can move, the system doesn't react. So what is wrong? I've even tried a electrical wire and it's not enough to short circuit the power?
Is this normal?
Thanks for any help.