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Will 8 Amps Damage My Engines?
Club member Frank has a question for readers:
“I have been dabbling in the hobby for some time now but only in a small space. I thought I would expand my N scale track in another room and go DCC with eventually 8 to 10 engines – that’s my dream. A fellow at the train show said an 8 amp unit might damage my engines and I would be safer sticking to 5 amps. I thought that sounded kinda weird?? Is he right?”
39 Responses to Will 8 Amps Damage My Engines?
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Hi Frank the guy give you the answer 8 amp is to much hi have reason , i be in n scale i use NCE Power Pro 5 amp , and my loco run great don t go for much than 5 amp , i expect this can help you
sylvain drapeau
canada
N gauge engines in my experience only take a maximum current of around 100ma so 10 locos is approx. 1 amp. Whatever power supply that comes with your DCC controller is the max current draw, to protect the controller, not the engines. If you require more power in a DCC set up you need a Booster which will increase power draw to the track but not through the controller. See manufacturers instructions for your CC controller.
Hi Frank I agree with Sylvain if u need more power because u are expanding use a booster or u can’t afford a booster u can use a computer power pack which is know more then 5 amps.
Your DCC circuitry will control what amps go to run the train. If you had 10 trains running full speed at the same drawing 1 amp each you would need a 10 amp power supply to run those trains. The odds that all trains would be running at there max would be rare.
An eight amp supply will not damage an engine. The 8 Amp supply will be required if you plan to run a lot of engines at one time. The key is to know how much power is required by all engines and other equipment and then be sure you purchase a supply that will provide that many amps.
This is correct. This applies to DCC, because the current drawn by a loco is limited by the electronics in the loco. If you are running plain DC (and AC in the USA) control, if the loco is stalled, many loco motors can burn out. For that reason DC controllers have a current limiter or cut out. This also protects the controller from burn-out. These of course normally only feed 1 or max 2 locos at any time. As people have said, you would need to be running a very large number of N gauge locos to need 8 amps, though it wouldn’t harm. It is important to not exceed the supply Voltage, as Jack Zahrly explains.
The amperage of you supply has no effect on you engines as long as it can provide the current that the engines requires. The important factor is the voltage. Your engine is specified to operate at a maximum voltage. At the maximum voltage the engine is specified to draw a maximum current. Your supply must be able to provide that maximum current in order to provide a maximum operating capability. Operating at a voltage above the specified voltage may cause damage to the engine.
If you want to extend track, you should minimize the voltage drop between your power supply and the extended track. To do that, use larger feeder wires from your supply to the extended track. Larger wires will have a smaller resistance and therefore a smaller voltage drop for a given current.
Mo; if you’re going to run multiple units and your wattage is insufficient for that load, then it would burn-up your engines. Say you have a light fixture in your home that is rate for one (1) 60 watt bulb, but you wanted more light and you placed one of those multiple light devices into that one socket that’s for one bulb. Now you have increased the lighting output of the one socket and its using three (3) 60 watt bulbs, so you’ve increased the wattage of that one bulb socket from 60 watts to 180 watts. You will burn that socket up.
So if you increase the size of your layout with out increasing your wattage or amps, you would then burn your engines-up. The damage comes when you do not have enough power (amps) to for the load on the track (your engines, cars and tankers. They are all a part of your load.
Hope this has in some way helped.
Henry.
Wouldn’t that burn up the controller, not the engines?
As Justin Bannah says, this would burn out your power supply, NOT your engines. Unless the power supply had some sort of fault that caused it to put too much voltage on the rails, the engines would be fine. In fact, most power supplies are well able to supply the current required by 1 train, so when only one train is running, they could easily supply enough current to destroy the train. This doesn’t happen because the trains draw current based on the VOLTAGE the power supply supplies, not the current it is ABLE to supply. Most circuits draw current based on the voltage supplied. The power supply supplies the voltage, up to the given maximum current that it is able to supply. Most loads attempt to draw the current they need. If that is less than the maximum the power supply can supply, then all is well (assuming no faults). If the load tries to draw MORE than the supply can provide, that’s when there’s problems. The vast majority of modern power supplies have some sort of protection built in so that they won’t be harmed, and they will supply a LOWER voltage to the load, not a higher one. In some cases they switch off entirely. So the trains will not be harmed.
The only reasons I can see to pick the 5 A over the 8 A are:
1. The obvious one – price.
2. If there is a short somewhere then the 5 A supply will put less current through the track up to and through the short, which MAY mean less damage to the track (like points/turnouts) or wiring. Most modern power supplies have short circuit protection of some sort and should at least partially shut down until the short is removed.
Very weird! Actually I think impossible. Somebody correct me if I am wrong but I don’t think the amps of your dcc system matter as long a you have enough amps to run all your engines. you will run into trouble if you don’t have enough amps for the locos you are running!
Having 8 amps will not harm your locos. Not having sufficient amperage won’t hurt your locos wither, but they will probably not run as fast as they should, and perhaps some features will not work properly. The critical thing is not wattage, but voltage.If your voltage is too high, then you WILL damage your locos motors, and burn out lights and other accessories.. Whatever you run on your layout will determine the amount of amps you consume, so if you have 10 locos running and they each need 1 amp, then 8 amps would not be sufficient. If you had a 10 amp power supply, and your total requirements are 9 amps, then your power supply will put out 9 amps, as much as you ask of it. Your power supply just cannot supply more than it is rated for. Asking more than it can supply could overload and over heat your power supply.
Wattage absolutely does matter. w=amps x volts so if wattage is low you cannot get the correct wattage on your motor,the amp may be there but at the expense of the volts,which will drop leading to eventual “brown out of motor windings.
Frank,
You’re in N scale, you want to run 10 locomotives at one time you will need at least 8 – 10 amp system because the decoders will need to access about an amp each to run the engines at normal train speeds with a train attached.
The guys are right about voltage, and voltage drop (or surge). That will ruin your loco motors if not right. Use heavy bus wires around your layout. Drop a feeder from EVERY piece of track and wire jumpers between each section or piece of track. Your DCC dealer can advise you which is best, but if extending the layout it might be a good idea to break it into districts and add in boosters.
Hope this helps
David
To follow up, I shouldn’t have said wattage isn’t important. You have to understand what that measurement is, and how it is calculated. Voltage, times amperage equals wattage. So, if your power supply is rated at 12 volts, and your loco draws 1 amp, then the requirements is 12 times 1. or 12 watts of current. If your power supply is rated in watts, then you’d have to divide the wattage rating by the voltage of your system. (i.e. a 120 watt power supply, on a 12 volt system would deliver 120 / 12 = 10 amps) If you purchase your power supply from a hobby shop, you shouldn’t have to worry about the voltage; they’re all the same.
All that to say, your power supply should exceed , not be less than your requirements.
I agree with the others that say it won’t hurt.
If your system needs 5amps and you use a 10amp supply, it’s like driving a V8 and only working it as much as you would a 4cyl. You will have spare power for extra if needed.
I run an HO layout and several trains on DCC and only use a 5amp, but would be quite happy to run a 10amp.
Only SMALL problem with a too bigger supply is using the extra mains current to drive it.
Idling current is always there.
Cheers Derek.
If you have an 8 amp supply it will not damage your engines they draw a set amount but on the other hand if you have a 5 amp supply and want to draw 8 amps then this will result in two things. the first is a reduction in volts and that could damage your engines and the second condition is the transformer will produce heat and this heat could produce fire which you will not want. I would rather have to many amps available than not enough. I run a supply that will allow 15 amps to be drawn before it will cause voltage drop or heat, so it idles along drawing 5 amps that equal 5 engines running at any one time or even just one engine running. I hope this helps you, thanks for asking the question.
Being in the Electrical Trade all my working, Much better to stick with 5 Amps or less.
Regards Wally
Why limit yourself 5 amp? It makes no difference 0,5, 5, 50 or 5000 As long as your equipment is suitable rated there won’t be a problem.
As several have already said, your trains and equipment will use only as much amperage as they require, as long as your power supply is adequate. Voltage is critical, but you need enough amps to power all the stuff you wish to run at one time. I’d vote for the higher amperage unit to accommodate future expansion if not needed immediately.
Hi,
We run up to 6 locomotives at one inc Shunting Loco’s our supply is a Hornby Elite which can run 99 loco’s at once for DCC which is 16 volt output for the track . The Elite has not got amps marked so I imagine it produces 8 -10 amps to supply that amount of Loco’s.
Hope that helps as my partner knows more about amps and voltages as she is an electrician. Also we have bought an extra unit for lighting and points Which is a Fusion Adjustable Power Supply which gives out Voltage and Amps That can operate from 1 amp up to 12 amps and the Voltage from 1 Volt up to 13 Volts.
Hope all this helps
In general terms, an 8amp power supply will not harm your locos. The locos will draw as much currant as needed to operate. The more locos running, the more current will be drawn from your supply. Therefore the supply needs to be big enough to cope with demand, plus say 30-50% in reserve.
What becomes an issue is if a loco shorts out, either within it self, a derailment, and so on, the loco is then at the mercy of the full current output. This means the potential of melt down and fire. The power supply should have a protection device to shut it self down in the event of a short.
Daryl.
Hi
No 8 Amps will not damage your locos.
With regards to amps, the locos and DCC controller will only take what it needs (upto the 8 Amps) but as been said already if you want more trains then you need a booster, this is like a repeater. It copies the signal and keeps the allowable current consent along the whole track.
The other way is to build a bus-bar under the whole track (this is what I am doing with my HO layout), the bus-bar is 2 cables (about 1.5mm single flex) which goes in a loop around the whole board and has pick ups from that to the track at multiple locations.
with track being so long you can get 2 problems:
1. Voltage Drop (the voltage will be lower at the furthest point from where your controller is connected to the track due to the resistance of the track)
2. Current drop (this is as a result of the voltage drop – the less voltage you have, the less current that will be available at further points of the layout)
The Bus-bar system will fix this problem. its best to you 1.5mm cable as this can take about 18A without burning out and due to the size (and the resistance of the cable) it reduces the likely hood of voltage drop and current drop.
Hi Frank,
I have run my N gauge on a computer supply box, this gives me 12v and 16amp
most N engines will never draw any where near that. the electric motors will only take what they require, and will only increase amp draw during hi load times.
As a foot note , if you are going to DCC and you have non DCC engines, do not try and run them on the DCC track, it will burn them out. HO is another story.
Frank. DCC especially Digitrax will run an HO DC engine OK using a ZERO-Zero code, Not sure if the other systems do. I would not let it sit at idle though as it is a higher voltage and constant to the engine motor as it is usually connected to the frame direct. I have a Kato Amtrak Engine that is only DC and on the box it says not to put it on DCC without the chip as you will burn the motor up. (the motors are in the trucks and are probably a little different). But that is OK as I have the new DCC chip now to install so it will not be long for me to run in style anyway.
Digitrax has a setting that you set for HO or N Scale. I am not sure what that limits though, I Will have to look that up. I am not sure if the other systems do that.
I still would not run an engine much on that Zero-Zero code as it can still heat up the motor. It is really just to be able to see how it runs on the system. The engine was made in 1962 and does not have a can motor on it. That run was done on the zero-zero code on Digitrax system and ran fine. But we did not run with a load and only a few times around and on DCC the voltage is a little higher. We also did not leave it in the stopped position as without the chip the motor will get the higher voltage all the time.
from Newman Atkinson
5 amps is more than enough for almost any home layout HO or N running up to about 20 to 25 engines. If I check the amperage draw on a stalled engine it is usually about .15 amps on new engines and about .65 amps on old brass engines. the engines will also be fine with 8 amps which is what a club layout usually is at because of the length of bus line feed wire from the power supply to the farthest location. The bus wire should be at least 14 gauge and the feed wire to the track sections should be about 18 gauge. The danger that no one has picked up on is when there is a short from a derailment. 5 amps does not usually do any damage if the short is found in a short time, but 8 amps will melt things, like engine parts, car wheel/trucks and turnout plastic parts. I know we like to think there will be no derailments but they usually occur during open houses when it is very inconvenient and you can not get top it quickly. I have been running DCC on both a 20ft x 30ft home layout and a 12ft x 65ft club layout. I would recommend 5 amps every time.
If you have DC engines and you try to run them on DCC you must run them on address 0 and NEVER leave them sitting idle on the track as this will burn out their motor in about 3 – 5 minutes.
Have fun with your modeling.
Regards Barry
Frank: My club runs a fairly large , two main layout with a yard, some independent industries, town with passenger station, and trolly system. Four of us can run at the same time. We are running 5 amps with no problem. We are in the process of doubling the size of the layout and adding more signals and powered switches and another service yard with turntable, so we are looking to upgrade to 8 amps. So with out knowing what you want to do with your lay-out, either power system will work fine depending on your layout and running requirements.
I think you should have 5 amps for now then when you expand it switch to 8 amps. If you have 5 amps for that big of a railway, the trains might stall.
I agree with all that is said above. Your engines and accessories will only use the amount of amps required when running, but the voltage is critical. You can also run an amp meter in series with your positive side of your feeder and a volt meter across your positive and negative of your feeder to monitor your current and voltage. I found a site that might be helpful. http://www.wiringfordcc.com/track_2.htm
Hi.You dont have to worry about the amps being to much as a loco will only draw the amps it needs,so if the loco drew 1 amp max and you had a 10 amp supply, you would still have 9 amps left,There is always misconceptions and misunderstanding by those who do not know or understand these things.If on the other hand you only had an half of an amp you would run into trouble and of course overload your supply.A normal 5 amp power supply is enough for a few trains to run at the same time.a ten amp supply would be needed if you are operating with friends and they are running double headers along with you. Use the wiring method sugested by nick owen.I too use droppers ,one for each section of track,I do not solder track joiners together,so if you have a pick up problem you know it is only local.I would use the 10 amp supply for 10 locos
Dear
There is confusion when they think of power a power supply. If a source is capable of providing 8 Amps, does not mean that anything you put in the layout will consume the total power supply. This is not true.
A locomotive or an electric system, will only order what is necessary for her work, even if that source is of very high power, far beyond the capacity necessary for this system to work. Being within the correct operating voltage, everything will work normally.
If there is a short circuit between the source and the locomotive, the power supply protection system is triggered and protect the power supply.
The problem is whether the short circuit is inside the locomotive. In this case, a power supply of smaller capacity, trigger the protection system earlier, when a lower current would make the protection system work faster. Being a high-power source, it may happen that when current reach a value that triggers the power supply protection system, the locomotive is already destroyed.
We should design the power supply capacity to around the maximum power value that we solocitar. If we ask 1Amp. current source, there is no need to use a power source of 8 Amps. Is it too.
Greetings
J.Oscar
An electric fence, with thousands of Volts connected to it, not kill an animal or a human being to touch her, in normal conditions. It turns out that animal or person will lead a uncomfortable shock, but not suffer further damage to discomfort.
What happens is that human skin, in normal state has a resistivity too high and does not allow the current that passes through the body is in itself sufficient to cause damage to person or animal.
But if the human skin is damaged, with a wound or any product that reduces the natural resistance of the skin, then pull on a device electric, even a 1,5VDC battery, the current will pass through the body of the person can be enough to cause damage and even death.
ELECTRIC CIRCUIT everything can be replaced by a battery and a resistor, with battery sinificando the power supply and resistor meaning throughout the circuit outside of it. While the conditions of the external circuit remain normal, the current drawn from the battery, it will be normal and not cause damage to the circuit, but change these conditions and anything can happen, either for more, or to less.
When we study electricity, also learned that a power supply can be represented by a ideal battery, associated with an internal resistor which will limit the amount of current that the battery will provide to power the external circuit, in normal working conditions. Above parameters designed beforehand, this resistor does not interfere in the functioning of the external circuit, but out of those patterns that internal resistor passes to influence and battery stops behaving in the normal way, limiting the voltage and current supplied by the power supply.
When we buy a 8Amps booster, the manufacturer guarantees that, in normal conditions, that will provide booster Zero to 8Amp to our layout, without their characteristics change. Above 8Amp, the manufacturer tells us that a circuit protection (if it exists) will become operational, changing the characteristics in a controlled mode, so he does not burn himself or has damaged its integrity.
The manufacturer does not guarantee that, if in your layout there is any device that collapses with any current value between zero and 8Amps it will not be damaged.
When we connect this booster to our Layout, everything connected to it will work in a normal way, if it is within its normal characteristics and the total ccorrente requested from the Booster is within these limits Zero to 8Amps.
Above this limit, the Booster protection circuit will enter in service, only PROTECTING THE BOOSTER against damage, until the limit set in your project.
If the problem in layout, is not controlled in time or extrapolate Booster protection limits, itself will be damaged.
So in our layout we use a Booster 8Amps to feed a N scale locomotive that consumes 100mA, nothing will happen to the locomotive and it will work normally. However, if your engine be short circuit and request the Booster ten times more current (1Amp), for the Booster it will be as if everything was normal, even if the current is enough to make our little engine catching fire.
Protection circuits may also be present within the locomotive decoder, protecting it from damage, such as a locked motor, but always within predefined limits in circuit design.
There is no universal protection for anything that happens.
Everything works within the parameters established in projects and what extrapolate these limits, will be unprotected.
It is up to us to establish what we do when we designed our Layouts.
Greetings
J.Oscar / RJ from Brazil
I want to explain it in a way that can educate a bit. Let me make the common analogy with water. Think of volts as pressure (think how high a water tower is above the supply pipe). Volts symbol in electronic formula is E. Current is the volume of water that flows through the pipe and that is determined by the small hole (think the hole is the draw that your loco takes). The electronic symbol for current is I and is also called amps. Now, the amount of water that flows with a given pressure is controlled by how big the leak is. This relationship is E = I * R. Your engine has a specific R, your power supply has a voltage output, E. the I that is drawn, then your local only draws what the loco requires. The amps capacity of the power supply denotes the total amount of current the supply can continuously be drawn out of the power supply. The larger current power supply will be able to power more things when your layout grows. The smaller power supply, the 5 amp unit will still power a lot of things.
Whether 5 or 8 amp that sort of power will do a hell of a lot of damage if you get a short circuit, especially if you use inadequate droppers, as a car mechanic dealing with electrical problems I have seen many cases of melted wires where 5 amp 60 watt spot lights have been wired with inadequate wiring, it is only a matter of time before someone burns their house down using these crazy amperages, I have seen OO gauge fishplates glowing red hot on 2 amps (24 va) so be very careful.
An average HO loco with no rolling stock running at 12 volts [full speed] uses approximately 200 milliamps of current but could be exceeded if it’s pulling rolling stock about 2 metres long with the extra weight . Some DCC controllers may have current limiting to protect the actual power supply from being overworked . Using a 5 amps or 25 amps will not make any difference to the running of your trains . It will only mean that you can run more trains and accessories and you will often find that running 10 trains at the same time can often use less current than all the other accessories on your layout combined . You can install a 1-10 Amp ammeter on your main power supply feed to monitor the entire current consumption on your layout , including lighting . A voltmeter also comes handy too . Loco motors , like many other DC motors can burn out due to over-voltage but it’s regulated by the DCC controller for the tracks . Most large layouts for analogue HO use the common 18 volt , 6 amp continuous , 10 amp peak power transformers . Obviously the voltage is too high so regulators and hi-pass current transistors are used to bring the voltage down , while maintaining the high current at the output . Like all circuits , especially running high current , circuit breakers or fuses must be used . An old trick to detect a short and protect wiring was to use a 12 volt , 21 watt globe in series with your power supply . A car trailer lamp can be screwed onto the control panel that will light if there is a short . I have found in the past that reducing the speed to very low speeds on an analogue layout that’s supplied with high current , tends to make the tracks dirty quickly so more frequent cleaning is necessary . It’s over-voltage that can damage a motor , not too excessive current .
Electricity is a funny thing. Electric motors, regardless of the size, draw as much current as they need-unless you get a short then they draw far more than they need.
As noted in a couple of the comments, the maximum load for the system is what should be concerning you, not what the loco is absorbing-this is limited by the design unless you overload what it is hauling-then it struggles and draws more current..
Having a power supply at 5 amps rating says that is all you can get-not all that is available to locos-unless you get a short! Exceeding the current rating will generally shut down a quality power supply as it overheats.
8 amps says I can run a lot more locos.
I have test track for ‘any’ Loco be it DCC or DC, the latter will run on very low voltage, i.e. 3volts, because the power supply I use for that is 30amps. You guessed it-I am a HAM. That is in an upstairs room and my Locos are in the loft. But it wouldn’t make any difference if I used a similar power supply for the DCC, like others have said, the system-including the loco will only draw what it requires, if there is a short anywhere, that in its self will draw current (VxA) until something gives, and the heat will destroy that which is the weakest link-as they say..
Bob G0EDK
Hi I run an NCE power cab with a 5 Amp booster + extra controller on a round the room layout which measures 5 metres x 4 metres x 5 metres x 600 mm wide with 5 main lines + sidings. The loco’s are set to a maximum scale speed of 50 MPH and I run 9 loco’s all with sound Decoders and they seem to run without problem. I’m only new to the hobby about 3 years so I may be doing it wrong but it works for me plus I only run 3 feeders 1 on each length
38 widely assorted replies so far on this topic ! Could get confusing ! (And some replies are definitely in error !)
Every model railroader should study basic electricity and electronics, and then will be able to work out these things easily !
Here are some sites offering free courses for beginners. Have look at a few, and discover which one(s) suit your approach.
http://www.allaboutcircuits.com
series of online textbooks covering electricity and electronics
http://www.learnabout-electronics.org/index.php
Descriptions of components and principles, good diagrams, animations, & fault-finding techniques
http://www.satcure-focus.com/hobby/index.htm
Useful range of ideas tutorials circuits links etc
http://electronics-for-beginners.com/links.php
http://www.hobby-hour.com/electronics/
Teaching from basic principles, resistor code calculators, projects
http://www.radio-electronics.com
Useful information and tutorials
http://www.electronics-tutorials.ws/index.html
Plus calculators & tools