U. S. Standard Wire Gauge.—This gauge is used for measuring sheet and plate iron, and steel, by the U. S. Government in assessing duties, and in making requisitions for supplies.
Old English Standard Wire Gauge.—The old English gauge is the same as the Birmingham or Stubs' standard gauge, commonly designated as B. W. G. It is used chiefly for measuring sheet iron and steel, also soft steel and iron wire.
London Gauge.—Old English (not Old English Standard).
From the foregoing it is seen that great confusion exists with such a multiplicity of gauges and emphasizes the importance of specifying the gauge and of knowing what gauge to use.
In using the gauges known as Stubs' Gauges, there should be constantly borne in mind the difference between the Stubs' Iron Wire Gauge and the Stubs' Steel Wire Gauge. The Stubs' Iron Wire Gauge is the one commonly known as the English Standard Wire, or Birmingham Gauge and designates the Stubs' soft wire sizes. The Stubs' Steel Wire Gauge is the one that is used in measuring drawn steel wire or drill rods of Stubs' make and is also used by many makers of American drill rods.
| Letter. | Size of Letter in Decimals. | No. of Wire Gauge. | Size of Number in Decimals. | No. of Wire Gauge. | Size of Number in Decimals. | No. of Wire Gauge. | Size of Number in Decimals. |
|---|---|---|---|---|---|---|---|
| Z | .413 | 1 | .227 | 28 | .139 | 55 | .050 |
| Y | .404 | 2 | .219 | 29 | .134 | 56 | .045 |
| X | .397 | 3 | .212 | 30 | .127 | 57 | .042 |
| W | .386 | 4 | .207 | 31 | .120 | 58 | .041 |
| V | .377 | 5 | .204 | 32 | .115 | 59 | .040 |
| U | .368 | 6 | .201 | 33 | .112 | 60 | .039 |
| T | .358 | 7 | .199 | 34 | .110 | 61 | .038 |
| S | .348 | 8 | .197 | 35 | .108 | 62 | .037 |
| R | .339 | 9 | .194 | 36 | .106 | 63 | .036 |
| Q | .332 | 10 | .191 | 37 | .103 | 64 | .035 |
| P | .323 | 11 | .188 | 38 | .101 | 65 | .033 |
| O | .316 | 12 | .185 | 39 | .099 | 66 | .032 |
| N | .302 | 13 | .182 | 40 | .097 | 67 | .031 |
| M | .295 | 14 | .180 | 41 | .095 | 68 | .030 |
| L | .290 | 15 | .178 | 42 | .092 | 69 | .029 |
| K | .281 | 16 | .175 | 43 | .088 | 70 | .027 |
| J | .277 | 17 | .172 | 44 | .085 | 71 | .026 |
| I | .272 | 18 | .168 | 45 | .081 | 72 | .024 |
| H | .266 | 19 | .164 | 46 | .079 | 73 | .023 |
| G | .261 | 20 | .161 | 47 | .077 | 74 | .022 |
| F | .257 | 21 | .157 | 48 | .075 | 75 | .020 |
| E | .250 | 22 | .155 | 49 | .072 | 76 | .018 |
| D | .246 | 23 | .153 | 50 | .069 | 77 | .016 |
| C | .242 | 24 | .151 | 51 | .066 | 78 | .015 |
| B | .238 | 25 | .148 | 52 | .063 | 79 | .014 |
| A | .234 | 26 | .146 | 53 | .058 | 80 | .013 |
The following table gives the diameters, in decimal parts of an inch, of the various sizes of wire corresponding to the number of gauge numbers of the different standard wire gauges used in the United States.
| Number of Wire Gauge | American, or Brown & Sharpe (B.&S.) | Birmingham, or Brown & Sharpe (B. W. G.) | Washburn & Moen Mfg. Co., Worcester, Mass. | Trenton Iron Co., Trenton, N. J. | G. W. Prentiss, Holyoke, Mass. | Old English, From Brass Mfrs' List | British Standard (S. W. G.) |
|---|---|---|---|---|---|---|---|
| 0000000 | .500 | ||||||
| 000000 | .460 | .464 | |||||
| 00000 | .430 | .450 | .432 | ||||
| 0000 | .46000 | .454 | .393 | .400 | .400 | ||
| 000 | .40964 | .425 | .362 | .360 | .3586 | .372 | |
| 00 | .36480 | .380 | .331 | .330 | .3282 | .348 | |
| 0 | .32486 | .340 | .307 | .305 | .2994 | .324 | |
| 1 | .28930 | .300 | .283 | .285 | .2777 | .300 | |
| 2 | .25763 | .284 | .263 | .265 | .2591 | .276 | |
| 3 | .22942 | .259 | .244 | .245 | .2401 | .252 | |
| 4 | .20431 | .238 | .225 | .225 | .2230 | .232 | |
| 5 | .18194 | .220 | .207 | .205 | .2047 | .212 | |
| 6 | .16202 | .203 | .192 | .190 | .1885 | .192 | |
| 7 | .14428 | .180 | .177 | .175 | .1758 | .176 | |
| 8 | .12849 | .165 | .162 | .160 | .1605 | .160 | |
| 9 | .11443 | .148 | .148 | .145 | .1471 | .144 | |
| 10 | .10189 | .134 | .135 | .130 | .1351 | .128 | |
| 11 | .090742 | .120 | .120 | .1175 | .1205 | .116 | |
| 12 | .080808 | .109 | .105 | .1050 | .1065 | .104 | |
| 13 | .071961 | .095 | .0920 | .0925 | .0928 | .0920 | |
| 14 | .064084 | .083 | .0800 | .0800 | .0816 | .08300 | .0800 |
| 15 | .057068 | .072 | .0720 | .0700 | .0726 | .07200 | .0720 |
| 16 | .050820 | .065 | .0630 | .0610 | .0627 | .06500 | .0640 |
| 17 | .045257 | .058 | .0540 | .0525 | .0546 | .05800 | .0560 |
| 18 | .040303 | .049 | .0470 | .0450 | .0478 | .04900 | .0480 |
| 19 | .035890 | .042 | .0410 | .0400 | .0411 | .04000 | .0400 |
| 20 | .031961 | .035 | .0350 | .0350 | .0351 | .03500 | .0360 |
| 21 | .028462 | .032 | .0320 | .0310 | .0321 | .03150 | .0320 |
| 22 | .025347 | .028 | .0280 | .0280 | .0290 | .02950 | .0280 |
| 23 | .022571 | .025 | .0250 | .0250 | .0261 | .02700 | .0240 |
| 24 | .020100 | .022 | .0230 | .0225 | .0231 | .02500 | .0220 |
| 25 | .017900 | .020 | .0200 | .0200 | .0212 | .02300 | .0200 |
| 26 | .015940 | .018 | .0180 | .0180 | .0194 | .02050 | .0180 |
| 27 | .014195 | .016 | .0170 | .0170 | .0182 | .01875 | .0164 |
| 28 | .012641 | .014 | .0160 | .0160 | .0170 | .01650 | .0148 |
| 29 | .011257 | .013 | .0150 | .0150 | .0163 | .01550 | .0136 |
| 30 | .010025 | .012 | .0140 | .0140 | .0156 | .01375 | .0124 |
| 31 | .008928 | .010 | .0130 | .0130 | .0146 | .01225 | .0116 |
| 32 | .007950 | .009 | .0120 | .0120 | .0136 | .01125 | .0108 |
| 33 | .007080 | .008 | .0110 | .0110 | .0130 | .01025 | .0100 |
| 34 | .006305 | .007 | .0100 | .0100 | .0118 | .00950 | .0092 |
| 35 | .005615 | .005 | .0095 | .0095 | .0109 | .00900 | .0084 |
| 36 | .005000 | .004 | .0090 | .0090 | .0100 | .00750 | .0076 |
| 37 | .004453 | .0085 | .0085 | .0095 | .00650 | .0068 | |
| 38 | .003965 | .0080 | .0080 | .0090 | .00575 | .0066 | |
| 39 | .003531 | .0075 | .0075 | .0083 | .00500 | .0052 | |
| 40 | .003145 | .0070 | .0070 | .0078 | .00450 | .0048 | |
| 41 | .0044 | ||||||
| 42 | .0040 |
NOTE.—The sizes of wire are ordinarily expressed by an arbitrary series of numbers. Unfortunately there are several independent numbering methods, so that it is always necessary to specify the method or wire gauge used. The above table gives the numbers and diameters in decimal parts of an inch for the various wire gauges in general use.
Wiring Terms.—The various members of a complex wiring installation are designated feeders, sub-feeders, mains, branches, and taps.
A feeder is a stretch of wiring to which no connection is made except at its two ends.
A sub-feeder is of the same class as a feeder, but is distinguished either by being one of two or more connecting links between the end of a single feeder and several distributing mains, or by constituting an extension of a feeder.