Topics

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.


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”.

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”.

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

 

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.

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.

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

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!

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.

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

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

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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Don Vollrath
 

Wyndell, you will not meet the safety intention of the (120V) electrical code by simply adding (cutting in) a switch and terminating the end of an extension cord in a duplex outlet box. Use electrician installed code compatible wiring, especially for club installations... permit and all.
DonV

 

Wago makes two similar types.  The older type is good but the newer one  is best.  They are the type 221.  Here is a listing on Ebay:

https://www.ebay.com/itm/Wago-221-Electrical-Lever-Connector-Terminal-Block-221-412-221-413-221-415/253063317158?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

The Wago parts are UL rated for household wiring as well.  Beware of the Chinese imitations.  They are not UL rated and may be fine for your low voltage stuff but don't wire them to 120V circuits.  I have used them professionally and on my layout and they are great.

Best,

Ken Harstine

Jerry Michels
 

We have had no problems doing this. As long as the rules for wiring 120v AC are followed.  We haven't have a need for switches along the extension cord, we have one at the beginning to disable the AC.  Our AC runs (in conduit and boxes) has multiple duplex outlets.  That is the reason for the AC in the first place, to distribute the AC to points on the layout where it is needed.


Jerry Michels

Amarillo Railroad Museum


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

thomasmclae
 

Just a reminder, there is a difference between Electrical Code and Electrical Standards.
Electrical Code prevents fires. DO NOT cut corners on this, as it prevents fires and electrical damage.
Electrical Standards make maintenance easier. Standards include:
Gauge of wire for applications. bus wire, track drops, etc.
Color code of wire. Track drop outside rail red, inside rail black, arduino power red/white, signal wires green/white, etc. Every wire should have a color assigned.
Connector types used. Suitcase, spade lugs, molex, etc. Especially critical for modular and sectional, but relevant for any layout. 

The more you document, the easier it is to fix something next year. (In my case, next month!)
You can set any rule you want, but follow that rule every time. Consistency is key.

Standards seem like a pain, but you are trading short term irritation for long term pain.
The first time you find a green wire dangling under the layout, and you have no idea what it was connected to, you will embrace standards.

Thomas
DeSoto, TX

Carl
 

Hi Gang:

One option that is approved is to mark the ends of a conductor. So if you have only black wire you could use colored shrink wrap to mark the code color.

I don't have the printer, but once I found a load of shrink wrap on carriers for printing. So you could print what you wanted on the wrap and then shrink it on the wire!

I also like terminals that allow me to remove one wire at a time, makes trouble shooting much easier.

The block on the left is for signals, the yellow/green terminals are connected to the DIN rail, notice the small green strip in the center of three terminals, connects six screws to the same circuit. The black terminals are fuses for turnout controls, one for each town. Track power is farther down.

As I have changed my power plans three times: Lionel AC to Lionel DMCC to Digitrax DCC these terminals made the changes possible.

Carl.

On 3/15/2020 12:01 PM, thomasmclae via Groups.Io wrote:
Just a reminder, there is a difference between Electrical Code and Electrical Standards.
Electrical Code prevents fires. DO NOT cut corners on this, as it prevents fires and electrical damage.
Electrical Standards make maintenance easier. Standards include:
Gauge of wire for applications. bus wire, track drops, etc.
Color code of wire. Track drop outside rail red, inside rail black, arduino power red/white, signal wires green/white, etc. Every wire should have a color assigned.
Connector types used. Suitcase, spade lugs, molex, etc. Especially critical for modular and sectional, but relevant for any layout. 

The more you document, the easier it is to fix something next year. (In my case, next month!)
You can set any rule you want, but follow that rule every time. Consistency is key.

Standards seem like a pain, but you are trading short term irritation for long term pain.
The first time you find a green wire dangling under the layout, and you have no idea what it was connected to, you will embrace standards.

Thomas
DeSoto, TX

Richard Sutcliffe
 

One of our local modellers prints the circuit identification on an Avery lable, applies the lable to the end of the wire, then shrinks a piece of clear heat shrink tube over the lable. Can use colour printing for extra identification.

Wish I had thought of this 40 years ago. But my wiring is still working. :>)

On Mar 15, 2020, at 9:43 AM, Carl <carl.blum@...> wrote:

One option that is approved is to mark the ends of a conductor. So if you have only black wire you could use colored shrink wrap to mark the code color. 


Jerry Michels
 

Thomas, better words have not been spoken! "Standards seem like a pain, but you are trading short term irritation for long term pain."   At the Museum, we follow this not only for wiring but also for things such as rolling stock, sub-roadbed, track, curve radii, and even mixes for scenery groundcover. For example we always find that the members whose trains are a problem at open houses and such are those who sneak in cars with plastic wheels, low or high couplers, unweighted cars, and locomotives with dirty wheels.  I have actually seen a boxcar with so much crud on the plastic wheels that it was even with the flange!  

Jerry Michels
Amarillo Railroad Museum

PennsyNut
 

The identifying of wires is not all the difficult. You could use pieces of straw. Cut 1" long, slice it and place it over each end of a wire. If you don't think that will "last", put a piece of scotch tape on it. You can get straws at almost every fast food place. Different colors. And if you are there buying something, and grab a few straws and stick them in your pocket, they won't say anything as long as you aren't grabbing a bag full. If a typical Subway straw is 7" long, you get 7 pieces 1" long and you only need two - one at each end of the wire. And you can get straws in different colors or in different sizes. Even stirring sticks have holes through them - but may not be large enough for some wires. This is my frugal way of doing things. And if you are putting these on the ends of the wires, you may not even want to slice them, put them over the wire the same way you put shrink on. The use of shrink wrap is a great way, but does cost. My way is free. LOL Morgan Bilbo, about one year with very basic DCC