SSPRR Run Room

Playing with Toy Trains

Toy Train Layout Wiring - Load Calculations

 

Basic Intermediate Advanced Wire Management Bus Wiring 120V Train Room
Glossary Plus Wire Sizes Switches Load Calculations Soldering Troubleshooting

The following formulas, examples, and charts can be used to "guesstimate" loads on a toy train layout. Circuit protection and wire sizing are determined by the total amps. Transformer sizes and total transformers needed are determined by total watts. When measuring current/amps always measure under load (with train or accessory running). Size circuit protection as small as possible for normal operation.

Limit Transformer loads to 75% of the continuous load.
Example - A 400 VA (watts) transformer will handle a 300 watt continuous load.

 

Experience has shown:
A small modern steam engine with DC motor and circuit board that converts AC to DC for motor will pull about 1 A and over 2 A with the smoke unit on. Overload the engine by pulling 20-30 cars on a main line with 8 to 10 A circuit protection and the motor or circuit board will fry before the circuit protection trips. Lesson - Size circuit protection for Divisions according to the loads used by trains. For smaller consists, 3 or 4 Amp circuit is good.

ABA six motored passenger engines and 10 lighted passenger cars can pull 8+ A. A lighted passenger car can pull 0.8 amps. For long passenger trains cars can be converted to LED lighting to minimize load.

A modern Big Boy can pull a 50 car freight train up a grade at as little as 4.5 A.

Big Boy Climbing

Electrician's Formulas

Description

Formula

Abbreviations

Ohm's Law for Amps

I = V/R

V = Line Voltage

volts = A x Resistance

V= IR

Vd =Voltage Drop

resistance = V ÷ amps

R = V/I

R = Resistance

Calculate Voltage Drop

Vd = 2KIL/CM

I = Current or Amps

Calculate Loads

VI = Watts

CM = Circular Mil

L = Distance

K = 12 for Copper

K = 18 for Aluminum

MCM = 1,000 CM

AWG = American wire gauge

CM VALUES

  AWG

CM

10

10,380

12

6,530

14

4,107

16

2,583

18

1,624

20

1,022

22

642

     LOAD CHART WIRE AMP RATINGS      

Lionel Postwar Items

Estimated Watts

AC Motor for Engines

15

AC Motor for Big Steam

25

AC Motor - Big for Access.

25

022 Sw and Controller lamp

5

Lamp

2.5

  Metered while running

2046 Hudson w/Tender

45

623 Switcher

27

Modern Era

DC Motor for most Engines

15

DC Motor for Big Steam

20

Smoke Unit

25

Lamp

2

Headlight - big

5

Marker Light

2

Metered
MTH Pass Car w 2 lamps

5

MTH Caboose w 1 lamp

7

Size

Wire Types

Amp Rating

24

CAT-2  3 pair Telephone

2.1 per conductor

24

CAT-5  4 twisted pair Data

2.1 per conductor

22

7 conductor irrigation cable

5 per conductor

20

2 conductor thermostat wire

7.5 per conductor

18

thhn for AC electrical

10

16

2 conductor lamp cord

13 per conductor

16

thhn for AC electrical

13

14

thhn for AC electrical

15

12

thhn for AC electrical

20

10

thhn for AC electrical

25

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This Laminated Chart of Lionel Postwar Bulbs was a Gift from a TCA Club Member 

Lionel Postwar Lamps

Parallel and Series Wiring Examples

Parallel Wiring Residential Wiring is Parallel wiring.  For train layout buildings and lighting, Parallel wiring is normally used.  The voltage remains the same the length of the circuit.
Parallel Circuits Formula
It  = I1 + I2 + I3     (I = current/amps)
Total current equals sum of amps through each resistor/lamp.

Some 4 Lamp Yard Lights are Wired with 2 Lamps in Series 

Series Wiring 

Series Circuits Formulas
Vt = V1 + V2 + V3     Total voltage equals sum of voltages across each resistor/lamp.
Rt = R1 + R2 + R3    Total resistance equals the sum of the individual resistors.

Light Bulbs

Question? Contact the SSPRR COO (Chief Operating Officer) using the email button to the right.  (If email link is absent, please enable JavaScript.) 

 

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