I’m looking for advice on what types of power supplies are suited to model railroading and how to wire them.
I would prefer to not have umpteen dozen wall warts plugged into multiple power strips. I would like to have a few larger power supplies from which the various components of the layout can be powered.
Specifically, I am asking if something like this power supply will work if I use four of them:
If they will work, which terminals do I connect to?
I have calculated that I will need about 40 amps to feed the whole layout. That includes 23 amps to feed 50 meters of LED strips, 6 amps to feed the DCC system, and about 10 amps to feed structure lighting, street lighting, vehicle lighting, and 30 or so tortoises.
All the power draw estimates include about a 15% safety margin. Is that enough?
Also, are there any guides out there which explain how to put all of this together? I understand the DCC aspect pretty well, but my understanding of how to distribute the power to the rest of the components is a bit vague.
I love camp fires, but I would really prefer to not start one in my garage![swg][(-D][(-D]
I have amassed many dozens of various power supplies in my quest for “electronic nirvana” on my layout. I have used some of the type you show in your link but keep in mind that many of these are not UL or CSA rated and may pose a risk due to poor quality or workmanship… however mine are still going strong but I only load them to about 50% since I do not trust some of the capacity claims.
The bad thing about these is that the high voltage terminals are right next to the low voltage ones and ARE exposed so you run the risk of shock, OR accidentally kicking 115 volts into your layout unless you put them into a secondary enclosure.
If you wire them CAREFULLY you’re OK but a strand from the hot to either of the low voltage terminals will make things go poof real quick.
The terminals on mine are clearly marked: line, neutral, ground: + out, — out.
[edit] I see in the third photo on the ebay page in your link that this model has line, neutral, ground, two commons and two pluses so there is more distance, but still a bit of a risk if you don’t protect those Hi Voltage terminals.
I bought one of these last year and it turned out that it would only provide about 25% of the stated capacity! Yet it gets 4 stars?
I put a 4.5 amp 12V light bulb on it and it tripped the overload. Amazon gave me my money back and said to keep the thing, we don’t want it back. It works fine for my Tortoise power supply and the total
You have confirmed my concerns about the power supply that I posted the link to. The terminals are uncomfortably close together.
I had also looked at the CCTV power supplies with their enclosures, but now I understand the benefits of the way they are laid out much better. I also like the idea of being able to close them off with their included door panels.
I was aware of Rob Paisley’s web site but I will spend more time studying it.
Dave, you should know best how much power you require for your layout, so I do not mean to appear to challenge your calculation.
But, to my mind, 40 amps seems incredibly high. As I am sure you know, 1 amp equals 120 watts, so 40 amps equals 4,800 watts.
I run a fairly large layout with 60+Tortoises, lots of signals and control panels, and an NCE PH-Pro DCC system, all off a 15 amp circuit including a dozen overhead fluorescent lamp fixtures.
Back to your question, it seems to me that you could simply install a 50 amp sub panel in your garage and run separate circuits to each segment of your layout.
Amps, Volts… 10 amps at 12 volts is about the same as 1 amp at 120 volts (or something like that) Out on the poer pole, the fuses that isolate our property from the utility are 100 Amp, but that is at 4000 volts. Chop that down, and we have plenty of ampeers for our entire campus.
Primary Power Supply of LION provides 10 volts at 10 Amps. Runs 10 trains. Ameters show LION has snever used more than 3 amps, but him knew that knot when him specified power supply.
LION does have several power supplies for different reasons. But if you are using all of those LEDs for lighting, in the valance or elsewhere, those should be separate from the model power, and should be specified by your electrician. Stick to the model power, and you will not use all that much.
The reason for using LEDs for lighting is they draw so little power. If you are using 40 amps, then there is something that I do not understand.
Third rail (above) is 650vdc… each car has 700 amp fuses, and 10 cars there are, ergo 7000 amps per train, and maybe three or four trains on a particular circuit at one time figure 40,000 amps draw possible. (And there are almost 300 trains operating during rush hour!) That is a lot of power. I’d go on, but that would be political, and Mr. Steve would withold my wildebeest if I did that. Do not ditz with the third rail, and if you are really using that many amps, you need an electrician.
Those sort of power supplies are used in all sorts of equipment. This is why there are ring terminals - you don’t take a line cord and wrap bare or even tinned wire around those screws, you put on ring (and rings, NOT spade) connectors and put them under the screw. The screw would have to fully back out for any wire to come loose. And of course you unplug the thing before messing with any of the wire connections/ The dual outputs make it easy to run two seperate 12V lines wach with a more reasonable 5 amp fuse in it.
Most of the ones like that when new have a plastic shield that covers the wire connections to you don’t accidently touch them. This comes off to access the terminals and should be put back in place for obvious reasons. The whole thing should be placed in a ventilated enclosure with a strain relief on the line cord and ideally a switch to turn it on and off, although just enclosing the terminal end is enough to prevent accidental contact. Think of a bus shelter sort of thing, or the covers over the third rail there in Lion’s photo - the business end of the power supply slides under there which keeps fingers and tools from the exposed terminals.
I’d just build my own, but the parts to make a quality power supply cost more than you can buy these things for, let alone design and build time. These things are cheap enough to even keep a spare on the shelf in case one fails during a critical operating session. With my planned LED lighting, I’ll need lots of amps at 12V to run it all - these things are just the ticket.
It seems high to me too, and I’ll readily admit that I don’t understand the power needs as well as I would like to.
Here is the logic behind my calculations:
Layout general lighting - I am going to use LED strips with 60 LEDs/meter. The layout is 24’ x 10’ on two levels. For the main level ceiling lighting I am going to use two parallel strips of warm white LEDs plus a bit more over the return loops, and I am going to run a single strip of blue LEDs around the layout as well for night operations. There will also be a single strip of white LEDs in the lower level which is all staging.
I calculate that the combined length of all the LED strips will be about 50 meters in total. If I understand the power requirements for the LED strips, each 5 meters requires about 2 amps @ 12 volts. That works out to 20 amps, plus a safety margin of 5 amps (25%) = 25 amps for the main lighting.
For the DCC system I am allowing 6 amps which is likely way more than I will ever use.
For the accessories like structure lighting, vehicle lighting, signals, street lamps etc., as well as 39 tortoises I am allowing 10 amps. If that seems high, keep in mind that I am an LED nut so I could end up with 300 - 400 LEDs on the layout.
I do plan on using an electrician. Before I go too much further I have to find out if I can get another 20 amp circuit out of my panel, which is 100 amps total. I had the panel replaced a couple of years ago and I had the electrician install an additional 20 amp circuit into the garage. At the time I thought that would be plenty but now I’m not so sure. Anyhow, my days of working inside the fuse panel are over!
Dave, I am neither a licensed electrician nor an electrical engineer, so I will leave it those who are more expert in this area to comment on your power requirements. But, given that cautionary note, let me make a few points.
Circuitron does comment on wattage by noting that a 1 amp power supply can control up to 20 Tortoises, so only 2 amps would be needed to power your 39 Tortoises. I agree that 6 amps is more than enough for your DCC command station. So, the remaining issue seems to be how much power you need to drive your layout lighting. But with 8 amps accounted for, another 32 amps (3,840 watts) for your lighting?
Regarding your 100 amp service panel, the total amperage of your circuit breakers can, and often do, exceed the service panel capacity. The key is the maximum number of amps being consumed at any one time. For heavy users of electricity, there will be an eventual need to upgrade the service panel and bring in a heavier line to your home.
Just an FYI, but those are rack-mount power supplies with exposed line-in connections rather than a socket/plug connection.
That means they have to be mounted in an enclosed equipment rack to meet applicable wiring/safety codes.
They look like they’re 2U, so you’d need at least an 8U cabinet. Standard size is 10U, so probably something like one of these.
Of course, you could just hang them under the layout or something, but if you ever have a house fire (even if caused by anything else) and the insurance co sees those, they’ll likely wash their hands and walk away…
I don’t think you’re out of line with the calculations. Note that a 12V DC power supply is going to be too low to supply the DCC system, so you will need a different source there.
One thing you must definitely do - run multiple power busses with individual fuses/circuit breakers. You do not want 12V at 10 amps running everywhere - that’s 120 watts and a short with some resistence can easily generate 100+ watts of heat without overloading the 10 amp supply. And if you’ve ever touched a 100 watt light bulb…
The LED strip lighting is a special case. You can conenct a few strips end to end, but at some point it no longe works since the current draw will cause too much voltage drop in the traces on each strip. This should be specified in the information for the strips. And I’d go half - if it says you can chain 4 strips, chain 2 and use heavy (#12 at least) bus lines to take power to the next set of strips, and so forth. It’s the same concept as having a track power bus and feeders. I’d still use multiple power supplies and distribute them around, having the bus runs go out to both sides to cover the greatest area with the shortest wiring runs. Don’t be tempted by higher current power supplies - they do make them, but I would not want to run everythign off a single 100+ amp power supply - not to mention when you get up to a certain level they end up needing 20 amp wall outlets and then eventually 3 phase power to run them. Relatively high current is unavoidable for the LED strip lights, but you should try to keep it in sensible chunks - also if all layout lighting ran from a single supply and that one failed…
For the on layout stuff, structure lights, Tortosies, etc - here is where the first thing after one of those hefty power supplies should be a board with multiple fuses/breakers on it, limiting things to an amp or 2 with multiple circuits. Things like building lights and Tortoises are generally wired with rather thin wire, since
What I wonder about in a situation like this is how to measure actual amps being consumed and at what point a breaker is being tripped.
While the situation is different, I had a toaster oven and a deep fryer on the same 15 amp circuit. Never had a problem running one or the other, but when we ran them both together, the breaker tripped. So, I rewired the circuit from 14 ga to 12 ga wire and changed out the 15 amp circuit breaker for a 20 amp circuit breaker and my problems were over.
When I added up the watts listed on the two appliances, the total was around 2,000 watts, as I recall. But is there a way to measure those watts (amps)? I just can’t believe that Dave needs 40 amps for this purpose.
OK you are talking about amps at 12 volts. LION would indeed use separate supplies for each level or zone of LED lighting. Ergo, stick with the wall warts.
12v Transformers at 25 amps would be VERY expensive, and not worth the effort.
Stick to the wall warts. You had it right the first time.
Thanks for explaining the proper housing for the rack mounted power supplies.
As Ed suggested, I am looking at power supplies that come with their own enclosures. The price isn’t significantly more than the rack mounted ones, and they come with multiple output connections already built into the case. They are primarily intended for CCTV applications. This is one example that Ed suggested:
Thanks for pointing out that I had included the DCC power supply in my 12 volt calculations. It would be run off of 110 volts using its own power supply.
Look at the thread from last week about blowign up power supplies with those LED strips. They take a lot of power. But this is amps at 12 volts - not amps at 120V, which, if the power supplies were 100% efficient, would be 1/10th - 40 amps at 12V is 4 amps at 120. More like 6 or so when you add in the inefficiencies in the power supplies, but still not taxing even a single 15 amp circuit.
Steve - I don’t think those power supplies are for full NEMA racks, they’d need shelves or some sort of mounts as well, they are quite narrow. They’e meant to go in some sort of chassis, which may or may not be rack mounted. SO if they are palced in some sort of enclosure that prevents contact with the terminals, that would be more than sufficient. There’s an AUssie guy with a YouTube channel, EEVBlog, does a lot of equipment teardowns and stuff, quite entertaining - one of the things he recently looked at was a 600V (!) 8 amp power supply, what uses 600V DC I do not know, but it was a 2U rack mount unit with effectively two power supplies internally paralleled to get the 4800 watts. Now this one needed phase AC input to run it - not only is it high power, it also is super precise. He got it for free - the company that bought it got a US spec model and tried plugging it in to AUssie 3 phase power (they use 240V there, not 120), and it promptly blew up. He tore it apart and found the blown components. Now that is a power supply - amazing build quality, also equally amazing price, many thousands of dollars.
