Re: Electrical Code for Train Layouts


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:

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, then click on “Publications” then “AppNotes”, and scroll down to a document called “Recommended Practices for 120VAC Layout Wiring.





John Wallis


From: <> On Behalf Of Carl
Sent: Wednesday, March 11, 2020 2:37 PM
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”.

Join to automatically receive all group messages.