Glossary

Flat Wire
SPT Stranded, Parallel, Thermoplastic. This is always followed by a -1, -2, or -3, signifying insulation thickness for different applications.
HPN Heater, Parallel, Neoprene. Required for heater type applications, such as irons, toasters, etc.
Jacketed Wire
S Stranded (or service wire)
J Junior Service (300 volts). If no "J" is in the wire type, then it is hard service (600 volts).
T Thermoplastic. If no "T" is in the wire type, then it has a rubber jacket.
O Oil resistant compound
W CSA approved outdoor use (weather)
W-A UL approved outdoor use (weather and atmosphere)
V Vacuum - as in vacuum cleaner. This is a small O.D. jacketed wire, very flexible and initially used for vacuum cleaners. It is now used on many different types of end products. Available only in 18 AWG.
Common Codes
HPD Thermoset insulated heater cord with cotton braid overall.
HPN Neoprene insulated heater cord.
MTW Thermoplastic insulated machine tool wire.
NM Non-metallic sheathed cable, multi-conductor building wire.
R, RH Rubber insulated wire. Building wire used for construction
S Extra hard service flexible cord for general use at 600 volts, rated at 60 C. Rubber insulated and jacketed.
SE Extra hard service flexible cord for general use at 600 volts, rated at -58 F to +221F. TPE thermoplastic elastomer insulated and jacketed.
SEO Type SE, but also rated oil resistant.
SEOW Type SEO, but also rated for outdoor use at -58F.
SEW Type SE, but additionally rated for outdoor use at -58 F.
SJ Hard service cord for general use at 300 volts, rated at 60 C, rubber insulated and jacketed.
SJE Hard service cord for general use at 300 volts, rated at -58 F to +221 F, TPE thermoplastic elastomer insulated and jacketed.
SJEO Type SJE, but rated as oil resistant.
SJEOW Type SJEO, but rated for outdoor use at -58 F.
SJEW Type SJE, but rated for outdoor use at -58 F.
SJO Type SJ, but rated oil resistant.
SJOW Type SJO, but rated for outdoor use at -30 F.
SJT Hard service cord for general use at 300 volts, rated -4 F to +140 F, PVC thermoplastic insulated and jacketed.
SJTO Type SJT, but also rated oil resistant.
SJTOW Type SJTO, but rated for outdoor use at -31 F.
SJTW Type SJT, but rated or outdoor use at -31 F.
SO Type S, but also rated oil resistant.
HSJO  Rubber insulated and jacketed.
SPT-1 Thermoplastic parallel cord for light duty, 300 volts.
SPT-2 Type SPT-1, but heavier construction, 300 volts.
SPT-3 Type SPT-2, but heavier construction, 300 volts.
ST Extra hard service cord for general use at 600 volts, rated at -4 F to +140 F, PVC thermoplastic insulated and jacketed.
STO Type ST, but also rated oil resistant.
STOW Type STO, but rated for outdoor use at -31F.
STW Type ST, but rated for outdoor use at -31 F.
SVT Vacuum cleaner cord, PVC thermoplastic insulated and jacketed rated 300 volts, 18 AWG and 16 AWG only, two conductors.
T, TW, THN, THHN, THWN Thermoplastic insulated wires. Building wires used for construction.
UF Thermoplastic underground feeder and branch circuit cable. Also used for submersible pump cable

 O.D Range

Gauge Conductors Types of Wire O.D Range 
18 2 sv,svt,svo .220-.255
18 3 sv,svt,svo .230-.265
18 4 sv,svt,svo .250-.285
       
18 2 sj, sjt,sjo,sjto .280-.315
18 3 sj, sjt,sjo,sjto .300-.335
18 4 sj, sjt,sjo,sjto .325-.365
16 2 sj, sjt,sjo,sjto .305-.340
16 3 sj, sjt,sjo,sjto .325-.360
16 4 sj, sjt,sjo,sjto .350-.395
14 2 sj, sjt,sjo,sjto .335-.375
14 3 sj, sjt,sjo,sjto .360-.395
14 4 sj, sjt,sjo,sjto .390-.435
12 2 sj, sjt,sjo,sjto .405-.445
12 3 sj, sjt,sjo,sjto .425-.475
12 4 sj, sjt,sjo,sjto .465-.520
10 2 sj, sjt,sjo,sjto .540-.605
10 3 sj, sjt,sjo,sjto .565-.635
       
18 2 s,st,so,sto .345-.385
18 3 s,st,so,sto .360-.400
18 4 s,st,so,sto .385-.430
16 2 s,st,so,sto .365-.410
16 3 s,st,so,sto .385-.430
16 4 s,st,so,sto .410-.460
14 2 s,st,so,sto .495-.550
14 3 s,st,so,sto .520-.575
14 4 s,st,so,sto .560-.620
12 2 s,st,so,sto .565-.625
12 3 s,st,so,sto .590-.655
12 4 s,st,so,sto .640-.710
10 2 s,st,so,sto .615-.685
10 3 s,st,so,sto .650-.720
10 4 s,st,so,sto .700-.775
8 2 s,st,so,sto .780-.880
8 3 s,st,so,sto .830-.930