Hawkins Electrical Guide v. 04 (of 10) / Questions, Answers, & Illustrations, A progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications

by N. Hawkins

or

ohms = feet × 10.8 circular mils . . . . (1)

(calling the resistance per mil foot 10.8 instead of 10.79 to facilitate calculation).

LAMP TABLE FOR RUBBER COVERED WIRES

Showing the maximum number of 16 candle power 110 to 240 volt lamps in parallel that may be carried by the various sizes of wire without violating the underwriters' rules.

Wire size B. & S. gauge	Amperes.	3.1.watt lamps.		3.5.watt lamps.		4.watt lamps.
		At 110 volts.	220 V.	At 110 volts.	220 V.	220 V.	230 V.	240 V.
0000	210	462	924	412	825	722	754	787
000	177	389	778	347	695	608	636	663
00	150	330	660	294	589	515	539	562
0	127	279	558	249	499	436	456	476
1	107	235	470	210	420	367	384	401
2	90	197	396	176	353	309	323	337
3	76	167	334	149	298	261	273	285
4	65	143	286	127	255	223	233	243
5	54	118	237	106	212	185	194	202
6	46	101	202	90	180	158	165	172
8	33	72	145	64	129	113	118	123
10	24	52	105	47	94	82	86	90
12	17	37	74	33	66	58	61	63
14	12	26	52	23½	47	41	43	45
16[3]	6	13	..	11	..	20	21	22

Now, according to Ohm's law,

volts = amperes × ohms . . . . (2)

hence, substituting in (2) the value for the resistance in ohms, as obtained in (1):

volts = amperes × feet × 10.8 circular mils