| Term | Definition |
| S | Heavy duty, rubber-insulated portable cord. Stranded copper conductors with separator and individual rubber insulation. Two or more color coded conductors cabled with filler, wrapped with separator and rubber jacketed overall. 600V. |
| S+ | Swiss Testing Agency symbol: SEV |
| SEOW(-A) | Extra hard service cord. Thermoplastic elastomer, oil resistant (TPE) construction Jacket. 600 volt, weather resistant for outdoor use. (A) -- The "A" has recently been dropped from the description. |
| Sheath | Pertaining to wire and cable, the outer protective covering (may also provide additional insulation). |
| Shield | A tape, serve or braid (usually copper, aluminum, or other conductive material) placed around or between electric circuits or cables or their components, to prevent signal leakage or interference. |
| Single PG | German conduit thread designation "PG". |
| Single Pole | A switching device is called single pole if it has only one pole. Switches which make and break a single circuit. |
| Single Pole Double Throw | A term used to describe a switch contact Form C that has a normally open and a normally closed contact with a common connection. |
| Single Pole Normally Open | A switch with only one moving and one stationary contact. Also referred as a Form A circuitry. |
| Single Pole Single Throw | A switch with only one moving and one stationary contact, available either normally open Form A(NO) or normally closed Form B(NC). |
| Single Stage | Single Function |
| SJ | Junior hard service, rubber-insulated pendant or portable cord. Same construction as type S, but 300V. Jacket thickness different. |
| SJEOW(-A) | Extra hard service cord. Thermoplastic elastomer, oil resistant (TPE) construction jacket. 300 volt, weather resistant for outdoor use. (A) -- The "A" has recently been dropped from the description. |
| SJO | Same as SJ, but neoprene, oil-resistant compound outer jacket. 300V, 60C. |
| SJT | Junior hard service thermoplastic or rubber-insulated conductors with overall thermoplastic jacket. 300V, 60C to 105C. |
| SJTO | Same as SJT but oil-resistant thermoplastic outer jacket. 60C. |
| SJTW | A hard service cord. Thermoplastic constructed jacket. 300 volt, weather resistant for outdoor use. |
| Snap Action | Switching action of interior switch. The action of the moving contact member that transfer from one position to another at a speed which is independent of the actuator speed. |
| SO | Hard service cord, same construction as type S except oil-resistant neoprene jacket. 600V, 60C to 90C. |
| SO-W | Heavy duty type 50-dual rated type W |
| SPDT | Single Pole Double Throw |
| SPNO | Single Pole Normally Open |
| SPST | Single Pole Single Throw |
| SPT-1 | Thermoplastic constructed, parallel jacketed, 300 volt, 2 or 3 conductors, 18 gauge. |
| SPT-2 | Same as SPT-1 but heavier construction. 18-16 gauge. |
| SPT-3 | Same as SPT-2 but heavier construction. 18-10 gauge. |
| ST | Hard service cord, jacketed, same as type S except all-plastic construction, 600V, 60C to 105C. |
| STO | Same as ST but with oil-resistant thermoplastic outer jacket. 600V, 60C. |
| Strip | To remove insulation from a cable or wire. |
| STW(-A) | Extra hard service cord. Thermoplastic constructed jacket. 600 volt, weather resistant for outdoor use. (A) -- The "A" has recently been dropped from the description. |
| SV | Vacuum cleaner cord, two or three conductor, rubber-insulated. Overall rubber jacket. For light duty in damp locations. 300V, 60C. |
| SVO | Same as SV except neoprene jacket. 300V, 60C. |
| SVT | Same as SV except all-plastic construction. With or without third conductor for grounding purposes only. 300V, 60C to 90C. |
| SVTO | Same as SVT except with oil- resistant thermoplastic jacket. 60C. |