# Wire Sizes and Spacing/Wire Resistance Table

## American Wire Gauge

The following table gives the size of various conductors, with the diameter in Mils. One Mil is 0.001 inches, or one one-thousand of an inch.

The resistance shown is that at 20º C.

It is worthwhile to note that cross-sectional dimensions are chosen such at each *decrease* in gauge number represents a 25% *increase* of the *cross-sectional area.* On this basis, a decrease of *three* gauge numbers will represent an *increase* of the cross-sectional area of 1.25 × 1.25 × 1.25, for an approximate increase of 2:1. Similarly a change of ten gauge numbers will represent a 10:1 change in cross-sectional area.

Since doubling the cross-sectional area cuts the resistance in half, a decrease of three gauge numbers will decrease the resistance of a given length of wire by half.

Applying the rule of 1.25^{Number of steps} allows for quick calculations for the increase or decrease in resistance between various wire guages.

For example, AWG 22 has 10 times the resistance as that of 12 AWG (10 steps). Or 14 AWG has 1.25^{2} or 1.6 times that of AWG 12's resistance.

Using that knowledge, a 10 foot run of AWG 14 is equivalent to 16 feet of AWG 12.

### Conductor Sizes

AWG Number |
Diameter, in Mils |
Ohms per thousand feet |
---|---|---|

10 | 101.9 | 0.9989 |

11 | 90.74 | 1.260 |

12 | 80.81 | 1.588 |

13 | 71.96 | 2.003 |

14 | 64.05 | 2.525 |

15 | 57.07 | 3.184 |

16 | 50.82 | 4.016 |

17 | 45.26 | 5.064 |

18 | 40.30 | 6.385 |

19 | 35.89 | 8.051 |

20 | 31.96 | 10.15 |

21 | 28.46 | 12.80 |

22 | 25.35 | 16.14 |

### Recommended Wire Gauge Chart

Wire Gauge Guidelines for a DCC Power Bus | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|

American Wire Gauge (AWG) | ||||||||||||

https://dccwiki.com/Wire_Sizes_and_Spacing | ||||||||||||

Scale | G | 0 | S | H0 | 00 | TT | N | Z | N−Trak | |||

Ratio | 1:20.3 | 1:29 | 1:48 | 1:64 | 1:87.1 | 1:76.2 | 1:120 | 1:160 | 1:220 | |||

Bus Length |
< 21 ft | < 6m | 12 | 14 | 14 | 16 | 16 | |||||

21 − 40 | 6 − 12m | 10 | 12 − 14 | 14 | 14 | |||||||

> 40 ft | > 12m | 8 | 12 | 12 | ||||||||

Feeder Wire Length |
< 5 ft | < 1.5M | 16 | 18 − 22 | 20 | 18 − 22 | 18 − 22 | |||||

< 10 ft | < 3m | 14 | 18 − 20 | 18 − 20 | 18 − 20 | |||||||

Recommended Wire Gauge | ||||||||||||

N−Trak is based on the N−Trak Wiring RP for DCC http://ntrak.org/ntrak_powerpole_rp.htm | ||||||||||||

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