Date   
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?




Re: Non-terminal snubbers

Paul O
 

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: Electrical Code for Train Layouts

Jerry Michels
 

Carl wrote: That said, I have seen bare 120volt terminals under layouts on tour. I think they was OK, there was a  label: "Danger, do not touch."  Also one where the 120volt lighting circuits looked just like the track wires, you just had to follow them to check what they were connected to.   

It is pretty foolish to have exposed 120v to begin with.  Having no labeling/signage is simply ridiculous! As I have mentioned  before, we use extension cords for our wiring, all male and female plugs removed so there can be no doubt that they are not regular extension cords.  We use orange extension cords in conduit and boxes for 120v.   Orange does not occur on the layout unless it is 120v.  In addition the cords originate in a sealed box, are labeled, and at the source we have signs. We also take a lot of precautions so that no visitors have an opportunity of "poke" around in our wiring.  Visitors can't even gain access to our control area unless escorted by a member. To encounter 120v, a person would have to open a box or undo conduit connections and ignore warning signs, i. e. been born in the shallow end of the gene pool.

Jerry Michels
Amarillo Railroad Museum

Re: Non-terminal snubbers

wirefordcc
 

Hi Michael,

Snubbers only go on the end of each run.  If you locate your booster in the middle of a track bus, as you should, you should put a snubber at each end.

Allan Gartner
Wiring for DCC

Non-terminal snubbers

 

I am building a layout with 4 Power Districts. Three PDs have the power supply located at their midpoint and have two track bus that are each less than 30 feet long. It would be helpful to have the fourth district have the power supply offset, producing a 20 foot bus and a 38 foot bus. All of the track bus will have terminal snubbers and twisted (3/foot) wires. Would it help to put a snubber midway on the 38 foot bus?
Thanks,
Michael

Non-terminal snubbers

 

I am building a layout with four power districts. Three of the PDs have the power source located centrally, allowing for two track bus of less than 30 feet. I would help to locate the fourth PD such that one track bus would be about 20 feet long and the other about 40 feet long. All of the track bus will have terminal snubbers. Would an additional snubber, located halfway along the 40 foot bus, help to decrease inductance?
Thank you,
Michael

Re: Electrical Code for Train Layouts

Carl
 

Hello John:

I used to set up some O-27 modules, but they never had any permanent 120v wiring, just a standard extension cord to the ZW transformer. I'm in South Carolina so I was never inspected by officials, Union or Public.

I've developed connectors for low voltage connections using PVC "wood" trim boards. It has been suggested that they don't meet "Code" for model layouts. From inspecting many under sides of model layout I wondered what Code might be??

So here is a link to the PVC terminals:

https://www.instructables.com/id/Insulation-Displacement-Screw-Terminals/

I was lucky and was able to use industrial DIN connectors rated for 600 volts, or telephone punch down blocks. So when a friend asked me to help wire his layout we tried the PVC blocks. We learned a few things, but they did work well and were easy make corrections. Let me know what you think.

Thanks, Carl.

On 3/11/2020 4:20 PM, John M Wallis wrote:

Hi Carl:

 

While the document mentioned below is intended for modular layouts set up in public venues, it does provide most of the rules laid out by the Fire Codes. Go to ntrak.org, then click on “Publications” then “AppNotes”, and scroll down to a document called “Recommended Practices for 120VAC Layout Wiring.

 

Regards,

 

 

John Wallis

 

From: w4dccqa@groups.io <w4dccqa@groups.io> On Behalf Of Carl
Sent: Wednesday, March 11, 2020 2:37 PM
To: w4dccqa@groups.io
Subject: [w4dccqa] Electrical Code for Train Layouts

 

Hi Gang:

Can anyone point me to the electrical codes that apply to our train layouts, the low voltage ( <12v. ) systems. By 120v. standards not much of what we wire would pass, DCC, DC or AC. I have a copy of Practical Electrical Wiring, based on the 1981 Code, so some things have surely changed. For low voltage wiring the main points are: 1) Do not put high and low voltage wires in the same conduit or box. 2) The supply should be protected from over current situations, 3) Thinner insulation is OK, but should be protected from damage. Nothing about terminals, protective boxes, etc.

I just want to know how to stay safe.

( That said, I have seen bare 120volt terminals under layouts on tour. I think they was OK, there was a  label: "Danger, do not touch."  Also one where the 120volt lighting circuits looked just like the track wires, you just had to follow them to check what they were connected to. )

Thanks, Carl.

 

Recommended Practices for 120VAC Layout Wiring”.

Re: Electrical Code for Train Layouts

John M Wallis
 

Hi Carl:

 

While the document mentioned below is intended for modular layouts set up in public venues, it does provide most of the rules laid out by the Fire Codes. Go to ntrak.org, then click on “Publications” then “AppNotes”, and scroll down to a document called “Recommended Practices for 120VAC Layout Wiring.

 

Regards,

 

 

John Wallis

 

From: w4dccqa@groups.io <w4dccqa@groups.io> On Behalf Of Carl
Sent: Wednesday, March 11, 2020 2:37 PM
To: w4dccqa@groups.io
Subject: [w4dccqa] Electrical Code for Train Layouts

 

Hi Gang:

Can anyone point me to the electrical codes that apply to our train layouts, the low voltage ( <12v. ) systems. By 120v. standards not much of what we wire would pass, DCC, DC or AC. I have a copy of Practical Electrical Wiring, based on the 1981 Code, so some things have surely changed. For low voltage wiring the main points are: 1) Do not put high and low voltage wires in the same conduit or box. 2) The supply should be protected from over current situations, 3) Thinner insulation is OK, but should be protected from damage. Nothing about terminals, protective boxes, etc.

I just want to know how to stay safe.

( That said, I have seen bare 120volt terminals under layouts on tour. I think they was OK, there was a  label: "Danger, do not touch."  Also one where the 120volt lighting circuits looked just like the track wires, you just had to follow them to check what they were connected to. )

Thanks, Carl.

 

Recommended Practices for 120VAC Layout Wiring”.

Electrical Code for Train Layouts

Carl
 

Hi Gang:

Can anyone point me to the electrical codes that apply to our train layouts, the low voltage ( <12v. ) systems. By 120v. standards not much of what we wire would pass, DCC, DC or AC. I have a copy of Practical Electrical Wiring, based on the 1981 Code, so some things have surely changed. For low voltage wiring the main points are: 1) Do not put high and low voltage wires in the same conduit or box. 2) The supply should be protected from over current situations, 3) Thinner insulation is OK, but should be protected from damage. Nothing about terminals, protective boxes, etc.

I just want to know how to stay safe.

( That said, I have seen bare 120volt terminals under layouts on tour. I think they was OK, there was a  label: "Danger, do not touch."  Also one where the 120volt lighting circuits looked just like the track wires, you just had to follow them to check what they were connected to. )

Thanks, Carl.


Re: Differentiating bus wires?

Jerry Michels
 

Sure, using a magic marker to put a color stripe on white wires would work fine.  Jerry Michels