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Will automotive fuses work for DCC short circuit protection?

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Will automotive fuses work for DCC short circuit protection?
Posted by CTConrail on Wednesday, December 26, 2018 10:24 PM

Ok so I have been searching the internet for the answer to this but to no avail. I am building my layout to be run by DCC (first time using DCC). I am going to break it up into power districts. I am trying to save money where I can and the NCE circuit breakers are $30 each. I know people use automotive lightbulbs to limit current in the event of a short which I know can still be dangerous and degrade dcc signal. Would it work to use automotive fuses instead of a dcc breaker or lightbulb? Thanks

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Posted by 7j43k on Wednesday, December 26, 2018 10:55 PM

Yes it would.

But when the fuse blows, you must replace it.  When a circuit breaker blows, you usually just reset it.

 

Ed

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Posted by MisterBeasley on Thursday, December 27, 2018 8:16 AM

You need fuses that are small, in the 3 amp range, less than the output capacity of your DCC system.

Eventually, you will tire of replacing fuses.  It will be a while before the fuse cost overtakes the circuit breaker cost, but that will eventually happen.

My advice is to wire your power districts now, but just depend on the DCC system for one big block of circuit breaker protection.  You can add breakers later. 

It takes an iron man to play with a toy iron horse. 

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Posted by CTConrail on Thursday, December 27, 2018 5:49 PM

MisterBeasley

You need fuses that are small, in the 3 amp range, less than the output capacity of your DCC system.

Eventually, you will tire of replacing fuses.  It will be a while before the fuse cost overtakes the circuit breaker cost, but that will eventually happen.

My advice is to wire your power districts now, but just depend on the DCC system for one big block of circuit breaker protection.  You can add breakers later. 

 

So basically just let the internal breaker in my NCE be my only source of protection until I buy breakers you're saying? Then just have the blocks wired up for when i do get breakers? I have a massive stockpile of fuses from when i worked as an auto electrician. Reason I want to at least run fuses is in case I step away for a sec and have a derailment I don't want one of my N scale engines becoming toast.

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Posted by BigDaddy on Thursday, December 27, 2018 6:38 PM

The plastic twin bladed fuses are rated too high for what you need.  The old time glass fuses can be found in sub 1.0 amp versions

I just watched a Youtube video, where the poster was breaking in a loco, left the room for an extended period of time.  The loco derailed at the turnout and the Procab kept resetting resulting in melted ties and truck.

Henry

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Posted by CTConrail on Thursday, December 27, 2018 6:58 PM

BigDaddy

The plastic twin bladed fuses are rated too high for what you need.  The old time glass fuses can be found in sub 1.0 amp versions

I just watched a Youtube video, where the poster was breaking in a loco, left the room for an extended period of time.  The loco derailed at the turnout and the Procab kept resetting resulting in melted ties and truck.

 

That's the exact video that made me start looking into this.  1 or 2 amp blade fuses are too high?

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Posted by BigDaddy on Thursday, December 27, 2018 7:21 PM

The DCC Specialties PSX circuit breaker is 1.27 amps for the NCE power cab.  My guess is that if it were set at 2 amps, the power cab would trip but the circuit  breaker would not.  But I am a guesser, not a guru.  I'd wait for a second opinion if I were you.  Smile

Henry

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Posted by selector on Thursday, December 27, 2018 8:01 PM

The limiting factor is not the system's capacity, say 5 amps, but the DECODERS' capacity!!!  They are more like 1.5 to 2 amps or so, and they'll smoke in a really bad way if you use 3 amp bulbs or fuses to limit damage.  Find out the maximum permitted current for all your various decoders, including those you may acquire and use in time, and then act to limit current damage accordingly.

If your controller's ability to limit current is suspect or insufficient, and you want to be more careful with the decoders, then use fuses or tail light bulbs in series that do not exceed the upper limits for your decoders.  But, if your wiring is good, your system should be able to manage shorts on its own.

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Posted by BigDaddy on Thursday, December 27, 2018 8:14 PM

The video is of an S5B booster.  Does a Powercab automatically try to reset?

Henry

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Posted by CTConrail on Thursday, December 27, 2018 9:30 PM

BigDaddy

The video is of an S5B booster.  Does a Powercab automatically try to reset?

 

I don't believe the powercab itself does but the booster does which i plan to get. So it sounds like 2a fuses are a possibility which I have many of but again I need to check all my decoders to be sure. Down the road I will probably try to get breakers but everything costs money and I can't do it all at once.

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Posted by peahrens on Thursday, December 27, 2018 9:33 PM

CTConrail
Ok so I have been searching the internet for the answer to this but to no avail. I am building my layout to be run by DCC (first time using DCC). I am going to break it up into power districts. I am trying to save money where I can and the NCE circuit breakers are $30 each.

I'm just curious, how many separate power districts (breakers) are anticipated?  Sometimes individuals lean, especially initially, towards more than needed by including some extra ones that seem "useful".  That can depend on a number of things, like a club layout where segregated areas and multiple operators can be a nice optional feature.  

But for a home layout, it can be as simple as one for mainline(s) and (typically) one per reversing loop.  Sometimes folks think it is necessary or very useful, say, to have a connected yard on it's own breaker to know where a problem has arisen.  But if there is only one operator, my case, it's usually obvious where a problem has occurred basis what is moving & where.

I only ask since the multiplier is a big factor in expense.  Six means $180, not insignificant.  Two is $60, etc.  Just for consideration.

An aside, if reversing loops are involved, the reversers vary in type and cost.  I went with $25 circuit breakers & $32 reversing breakers, finding I did not need fancier ones to combine with my NCE 5A Powerhouse Pro.  I was a novice, but trusted the advice I got at Tony's Trains, based on a discussion of my particular layout plan with my chosen DCC system.

https://tonystrains.com/product/dcc-specialties-onguard-og-cb-circuit-breaker

https://tonystrains.com/product/dcc-specialties-onguard-og-ar-auto-reverser-circuit-breaker

 

Paul

Modeling HO with a transition era UP bent

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Posted by CTConrail on Thursday, December 27, 2018 10:52 PM

peahrens

I'm just curious, how many separate power districts (breakers) are anticipated?  Sometimes individuals lean, especially initially, towards more than needed by including some extra ones that seem "useful".  That can depend on a number of things, like a club layout where segregated areas and multiple operators can be a nice optional feature.  

But for a home layout, it can be as simple as one for mainline(s) and (typically) one per reversing loop.  Sometimes folks think it is necessary or very useful, say, to have a connected yard on it's own breaker to know where a problem has arisen.  But if there is only one operator, my case, it's usually obvious where a problem has occurred basis what is moving & where.

I only ask since the multiplier is a big factor in expense.  Six means $180, not insignificant.  Two is $60, etc.  Just for consideration.

An aside, if reversing loops are involved, the reversers vary in type and cost.  I went with $25 circuit breakers & $32 reversing breakers, finding I did not need fancier ones to combine with my NCE 5A Powerhouse Pro.  I was a novice, but trusted the advice I got at Tony's Trains, based on a discussion of my particular layout plan with my chosen DCC system.

https://tonystrains.com/product/dcc-specialties-onguard-og-cb-circuit-breaker

https://tonystrains.com/product/dcc-specialties-onguard-og-ar-auto-reverser-circuit-breaker

 

 

Hmm...well my plan has a 2 track main and a yard with reversing loop so I guess a minimum of 3 districts I would want without overdoing it. Layout is not very big 9.5x7' but I want be able to run 2 trains and switch in the yard at the same time.

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Posted by rrinker on Thursday, December 27, 2018 10:53 PM

 For a PowerCab, and in N scale - I'd use 1 amp fuses for each section. If you have a good supply - and sockets for them so they just plug in, by all means, use fuses. 

 Also, even if just stepping out for a bathroom break, stop all moving trains. I never leave stuff running when I leave the room, for any purpose.

                                      --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by B. Bryce on Friday, December 28, 2018 9:43 AM

Since you stated you are only using the PowerCab, not a booster as of yet, a circuit breaker is pretty much worthless.  According to NCE, light bulbs protect the Powercab, circuit breakers protect boosters.  Since the smallest circuit breaker that I know of is around 2 amps and the Power Cab only puts out 2 amps, the breaker will never reliably trip, even with a short, to protect the Powercab, which is why they build in protection to the Powercab.  According to NCE, never use a breaker to protect the Powercab.  For the Powercab, according to NCE, either the CP6 light bulbs or automobile light bulbs is the correct way to protect things. 

Also remember, breakers don't always trip at exactly the rated current, and the lower the rating, the less accurate the trip point actually is.  A 2 amp breaker may trip at 1.5 amps or 2.5 amps, or even 3 amps, whereas a 5 amp breaker may trip between 4.5 and 5.5 amps. A 10 amp breaker may trip between 9.5 and 10.5, but this is far more than enough current to melt trucks and tracks, let alone decoders!  The higher the amp rating, the smaller the tolerance spread.

I started my layout with a Powercab and the CP6 device, which is fed by the Powercab and distributes track power in six 1 amp legs.  If you need more power than 1 amp, you can get a 1.75 amp bulb or parallel two 1 amp bulbs to get 2 amps, but mostly everything except large consists and a lot of lighted passenger cars should not need more than 1 amp, especially in N scale.

Now that my layout has grown and I have gone to boosters, I have a 5 amp circuit breaker on the output of each booster to protect my boosters from trying to put out more than 5 amps each, and the CP6 is still protecting my blocks of track.

I read on NCE's web site that you should use either the CP6 or the circuit breaker, not both, but I called Ed Wilson at NCE to find out why and he had no good reason why you could not use the breaker and the CP6 in series, in fact, he thought it was a great idea.  The key word here is connecting them in SERIES, never use them in parallel.

Circuit breakers protect boosters, light bulbs protect decoders.  The rational is that the 5 amp circuit breaker will protect the booster from overloading but not protect the decoder from melting if 4 of the 5 amps is suddenly going to a single decoder.  The CP6 will not totally protect the booster because it has six 1 amp lights, which combined can exceed the output of the 5 amp booster with no protective action by the CP6 either.  But, with the two in series, the 5 amp circuit breaker will cut off current if the load on the booster exceeds 5 amps, even if all the track segments are below 1 amp each, and conversly, the CP6 will protect the each of the track segment from drawing more current than the 1 amp bulb is rated for but still allow the booster to provide power to everything else.

Using a CP6 or light bulbs and a breaker in parallel is a definate no-no, as you can have 4 amps going through one and 4 amps going through the other, neither will protect anything and the booster will try to put out the necessary 8 amps and burn itself up.

Also, you don't need to use the NCE CP6, any form of light bulb will work as long as it is a resistance bulb, not an LED light bulb, or you can use a fuse.  Fuses are a hastle to replace and consumable, the light bulbs are self regulating and practically never need replaced.

I also agree with Randy, never leave the layout unattended and running.  You are asking for Murphy to do his worst!

If you are worried about the cost of a breaker or a CP6 or any other form of protection, consider the cost of replacing the locomotive or Powercab.  All of a sudden, the cost of protection is far less, and should be considered part of model railroading expenses.  

Old Chinese proverb, "There is never enough money to do it right, but there always seems to be enough money to start over."

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Posted by BigDaddy on Friday, December 28, 2018 10:03 AM

B. Bryce
Since the smallest circuit breaker that I know of is 5 amps

You don't know PSX and since NCE doesn't sell it, they aren't going to recommend it or mention it in their Zendesk info page.

To answer my own question, poking around the NCE Zendesk, the Powercab does reset itself, so in the youtube example of an unattended derailment, it would put out burps of 2 amps.  

Henry

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Posted by CTConrail on Friday, December 28, 2018 10:05 AM

Thanks for the detailed info. This helps. The way I look at it is when I get around to getting a booster I will look into breakers also but good to know I don't need them without the booster. I am still very new to DCC and have only been back in the hobby for a few months now. DCC itself was unaffordable when I left the hobby. 

Good advice also Randy, thanks!

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Posted by B. Bryce on Friday, December 28, 2018 10:24 AM

Hi Bigdaddy, I corrected my post to 2 amps apparently while you were writing your post.  Meant to say 2, but typed 5, probably because we were talking 5 amp boosters.  

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Posted by Redvdub1 on Thursday, January 03, 2019 8:28 PM

I would think the automotive fuses would "work" but would be too slow.  My club has used "bulbs" and we've never had DCC control problems because of the bulbs.  BTW...How are you going to "split" the DCC signal from the command station into "power districts"? 

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