Date   
Re: Non-terminal snubbers

Jim Zarnick
 

Congrats Allan!  I subscribe to several HO Facebook groups and when people start asking DCC type wiring question I habitually reference wiringfordcc.com J Looking forward to reading you in MR.

 

I’ve been paying close attention to this dialog as I wonder if my own snubbers are in the right place.  So I’ll ask.

 

I have NCE DCC hardware on the track circuits. (I used to live 2 miles from their shop so I’m loyal, J

 

Layout is multi deck  around the walls with a helix connecting one end of the wall based decks and a platform in the center of the room that connects the 2 decks, allowing continuous running.  Mainline is double and 267 feet long.

 

2 NCE Boosters

12 gauge stranded buses from Boosters. Boosters are wired together for common ground.

5 locations exist around the layout connecting  the buses to 6 NCE Circuit Breakers.

Each circuit breaker is connected to a multi terminal distribution panel like the Micro Structure product.  2 sides 10-12 terminals each side.

My snubbers sit on the bottom of these panels, so 1 snubber per circuit breaker protected district.

From the distro panels after the circuit breaker each block, which have insulation joiners on both rails, have a twisted pair of 18 gauge wire running to them.

One of the block wires runs through an NCE block detector.

Each piece of track has 22 gauge feeders connected the 18 gauge block wires (IDCs everywhere!).

 

So my snubbers are not at the end of runs, as technically the end of my runs are at the end of each block. But my snubbers are before the block detectors.

 

In general I have very few electrical issues but:

1)      I do have the occasional runaway, 

2)      I do have the occasional locomotive that stops and restarts while the other loco in the consist does not, and

3)      I do have an occasional issue with the block detectors not picking up the resistor wheelsets, which is annoying to the signal system and crossing gates.

 

Lots of info here, but welcome knowing if I have my snubbers in the best place?

 

Thanks for the great dialogs in this group!

 

Respectfully,

 

Jim Zarnick

 

 

From: w4dccqa@groups.io [mailto:w4dccqa@groups.io] On Behalf Of wirefordcc
Sent: Saturday, March 14, 2020 10:18 AM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Non-terminal snubbers

 

Hi Dan,

 

One common snubber at the end of the district that ties all the lines to it should work.  Do not put them after the block detector CT (current transformer) coil as you might get a false occupied block.

 

Starting in January, I will be writing the DCC Corner column for Model Railroader.  Can I use your question?  If so, please provide me with your city and state.

 

Thank you

 

Allan

Re: Electrical Code for Train Layouts

Wyndell "Wingnut" Ferguson
 

So what’s everyone’s thoughts on adding a switch in an extension cord and replace end connector with a metal box and 2 duplex outlets?

 

Wyndell

 

Cognitive Thought & Oppsable Thumbs (CTOT) RR

DCC on N Scale

 




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Re: Non-terminal snubbers

Mark Cartwright <marcdecapri@...>
 

Thank you Alan
Your page answered many questions I had not yet begun to know I had.
:)) Mark

Re: Non-terminal snubbers

Puckdropper
 

Has anyone tried using the coil-style adjustable block detectors with snubbers? Something like the Team Digital BOD-8?

Puckdropper

Re: Electrical Code for Train Layouts

PennsyNut
 

If I may? That's why I love those WAGO lever nuts. They are rated for AWG 28 to 12. So they hold and connect two or more wires and leave nothing exposed. What I did was strip the wires so that the insulation goes right up to the WAGO. And the reason I tried these in the first place was that I had two 22 AWG wires twisted together with "wire nuts". Again, carefully trimmed so no exposed wire. But they don't hold if you accidentally tug the wires. WAGO's do hold. I am not affiliated with them. Just a happy customer. They are a little pricey, but IMHO it's a good example of "you get what you pay for".  Morgan Bilbo, about one year with very basic DCC

Re: Electrical Code for Train Layouts

wirefordcc
 

On Fri, Mar 13, 2020 at 08:42 AM, Tim wrote:

I will need 120V receptacles on a couple of peninsulas on my layout. That will all be in EMT and metal boxes.

Tim Rumph
Lancaster, SC
Everyone has been giving prudent advice.  Let me just add a couple of things.  

Route your 120/220 VAC wiring away from your bench top so that you don't accidentally drill through it some day.

No exposed wiring or terminals like on transformers or fuse holders!  Even the low voltage output terminals on transformers should not be exposed; especially if the transformer is not fused.  Otherwise, if something metallic should short the output terminals of the transformer, a fire could result.

Allan Gartner
Wiring For DCC

Re: Non-terminal snubbers

wirefordcc
 

Hi Dan,

 

One common snubber at the end of the district that ties all the lines to it should work.  Do not put them after the block detector CT (current transformer) coil as you might get a false occupied block.

 

Starting in January, I will be writing the DCC Corner column for Model Railroader.  Can I use your question?  If so, please provide me with your city and state.

 

Thank you

 

Allan

Re: Non-terminal snubbers

Tim
 

Don't use a snubber on leads with current sensors, it will trip them and look occupied all the time.

Tim Rumph
Lancaster, SC

Re: Electrical Code for Train Layouts

Paul Deis
 

I am an old electrician and belive in safety both from shock and fire. There is also the concern of picking up 60 cycle interference on your DCC power buss. I route all of my 110vac thru flex conduit to proper juntion boxes. It protects from shocks, fire due to a short circuit and puts a little distance and additional insulation to reduce 60 cycle interference.

Re: Non-terminal snubbers

Daniel Brewer
 

Hi Allan,

If my power districts have a single black wire for ground, but up to 4 powered wires which I plan to use for detection (CT Coils using RR-Cirkits products-one red line each for approach, main, siding, approach). Could I have one "common" snubber at the end of the district that ties all lines to it? Does the snubber have any negative effect on detection? None of my bus wires are longer than 40 ft. Sorry for the "elongated" question.
Thx!
Dan

Re: Electrical Code for Train Layouts

Tim
 

I was at an old friend's who was having some power supply issues. Receptacles on the layout with no grounding or any way to insure the hot and neutral connections were right. Open 120V wiring under the layout. I told him not to call me when his house burned down.

I will need 120V receptacles on a couple of peninsulas on my layout. That will all be in EMT and metal boxes.

Tim Rumph
Lancaster, SC

No, I'm not an electrician, and I won't help you with this on your layout!

Re: Non-terminal snubbers

 

Hi Allan,
Thanks for your response. I am going to twist the track bus wires (three turns per foot) and put snubbers at all the ends. The one longer (40+ feet) bus got me to thinking about an article I read in Model Railroader, May of 2015, by Larry Puckett. In it he says, "try installing snubbers at the ends of each power bus, or even at intermediate points along a power bus." (my emphasis) He also credits Mark Gurries as the "technical advice" for the article, so I tend to give the comment so weight.
Do you think such an intermediate snubber would be of any help?
Thanks,
Michael Boyle

Re: Electrical Code for Train Layouts

JB
 

Please do not attempt to wire anything rated 120v. Or higher! More house fires and accidental electrocutions have occurred because a well meaning homeowner (layout owner) thought they were doing things right and resulted in serious consequences. Just because" it worked all of this time " doesn't mean you did it in a safe manner. 

I too have seen live,  unguarded 120v circuits under layouts and mentioned it to the person in charge.  Most times they say something like" I'm the only one that goes under there," Or "I'll look at it when I get a chance". Both mean to me that nothing will change for safety sake. 

Sorry four my ranting but if don't say something,  somethings might get hurt or worse.    At least consult a licensed electrician for advice.
Thanks
JB    Connecticut Master electrician- 35 years

Re: Non-terminal snubbers

wirefordcc
 

All,

I talk about snubbers (bus terminators) in my website at:  http://www.wiringfordcc.com/track_2.htm#a47  The information includes where you should put them - at the ends of your buses.

This information is included in the Track Part II section of my website.  An easy way to find the above link is to go to the site map of the website and click on "Snubber" under the "Track" topics.

If you are trying to help someone else, after you find the topic by the above method, you should be able to copy the above link from your browser and send it to them.

Allan Gartner
Wiring For DCC

Re: Electrical Code for Train Layouts

mgj21932
 

Ken Harstine
Thanks for incredibly useful info.
Bill D


On Mar 12, 2020, at 6:26 PM, Ken Harstine <kharstin@...> wrote:

Not aware of codes for low voltage.  UL considers anything below 40V as touch safe.  So we are left with possible heating of wires.

Make sure that all wire connected to a source (12Volts for example) will not overheat if the maximum possible current is present.  This includes the return wires as well.  The maximum current is either what your power supply is rated for or what your fuse or breaker (if present) will allow before interrupting the circuit.  Active circuit breakers probably don't count as many of them could fail to a short circuit and therefore might no help.  At least this is how UL looks at it.  You may decide to trust your active circuit breakers anyway.  So since we often use small gauge jumpers to connect our bus to the tracks we need to make sure that the circuit is protected to prevent that smaller wire from overheating.  So if you use 24 AWG jumpers you should make sure that no more then 3.5 Ampere can flow in the circuit.  22 AWG should be good for 7 Ampere.

Remember that not all short circuits will draw enough current to trip your beakers or your DCC box.

In addition to following the above rule I have my layout power wired to a timer.  This way a low level short that might cause local heating cannot persist long term.  What if some conductive debris should happen to fall across your buss.  It only takes 2 Amperes in a 12 Volt circuit to cause 20 Watts of heating with only 2 Amperes or current.  20 Watts is enough to start a fire. 

Best Regards,
Ken Harstine
30 Years experience with product safety and compliance with UL and other regulatory bodies.

Re: Non-terminal snubbers

Rich Randall
 

You are really going to love it if you need snubbers and don't have them.

From my experience: locomotives jerking, stalling, ignoring commands, and loss of brains, and occasionally, burned out decoder.

The info on the web is plain: Buss runs of greater than 30 feet from the booster, with non-twisted wire.

https://sites.google.com/site/markgurries/home/dcc-general-best-practices/wiring-planing/snubbers-rc-filter



Rich Randall
Gettysburg, PA

Modeling The Milwaukee Road
at Avery, ID, in O Scale

The BSME is now on facebook: 

Re: Non-terminal snubbers

Paul O
 

Carl, the symptoms you’ll see is erratic behavior of a loco (stopping, not responding to the throttle, etc.) on a certain part of the track, usually not far from the end of your bus wire. 
This one is kinda like the “if it ain’t broke, don’t fix it“ situation.

Much more info here:

Paul O

On Mar 12, 2020, at 2:38 PM, Carl <carl.blum@...> wrote:

Hi Gang:

How do you know if you need snubbers? What do you see? Is there a test?

Carl._._,_._,_

Re: Electrical Code for Train Layouts

 

Not aware of codes for low voltage.  UL considers anything below 40V as touch safe.  So we are left with possible heating of wires.

Make sure that all wire connected to a source (12Volts for example) will not overheat if the maximum possible current is present.  This includes the return wires as well.  The maximum current is either what your power supply is rated for or what your fuse or breaker (if present) will allow before interrupting the circuit.  Active circuit breakers probably don't count as many of them could fail to a short circuit and therefore might no help.  At least this is how UL looks at it.  You may decide to trust your active circuit breakers anyway.  So since we often use small gauge jumpers to connect our bus to the tracks we need to make sure that the circuit is protected to prevent that smaller wire from overheating.  So if you use 24 AWG jumpers you should make sure that no more then 3.5 Ampere can flow in the circuit.  22 AWG should be good for 7 Ampere.

Remember that not all short circuits will draw enough current to trip your beakers or your DCC box.

In addition to following the above rule I have my layout power wired to a timer.  This way a low level short that might cause local heating cannot persist long term.  What if some conductive debris should happen to fall across your buss.  It only takes 2 Amperes in a 12 Volt circuit to cause 20 Watts of heating with only 2 Amperes or current.  20 Watts is enough to start a fire. 

Best Regards,
Ken Harstine
30 Years experience with product safety and compliance with UL and other regulatory bodies.

Re: Non-terminal snubbers

Bob Miller
 

Check the current flow near the end of each buss. I found a spike near the end of a roughly 45’ buss using my RRamp Meter. I installed an NCE snubber and it disappeared.

 

From: w4dccqa@groups.io <w4dccqa@groups.io> On Behalf Of Carl
Sent: Thursday, March 12, 2020 2:39 PM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Non-terminal snubbers

 

Hi Gang:

How do you know if you need snubbers? What do you see? Is there a test?

Carl.

On 3/12/2020 12:50 PM, Paul O wrote:

Michael, no it’s not needed.
The purpose of the snubber is to reduce the reflected signal at the end of an unterminated buss; not needed in the center of a buss.
 
Paul O
 
On Mar 12, 2020, at 9:17 AM, Michael Boyle <boyle10017@...> wrote:
<snip>
Would it help to put a snubber midway on the 38 foot bus?
 
 
 
 
 

Re: Non-terminal snubbers

Carl
 

Hi Gang:

How do you know if you need snubbers? What do you see? Is there a test?

Carl.

On 3/12/2020 12:50 PM, Paul O wrote:
Michael, no it’s not needed.
The purpose of the snubber is to reduce the reflected signal at the end of an unterminated buss; not needed in the center of a buss.

Paul O

On Mar 12, 2020, at 9:17 AM, Michael Boyle <boyle10017@...> wrote:
<snip>
Would it help to put a snubber midway on the 38 foot bus?