| Manufacturer: | Osram - GEC |
| Model: | SOX 35W |
| Application: | Street Lighting, Security Lighting |
| Wattage: | 35W |
| Diameter (max): | 50mm |
| Length: | 300mm |
| Tube Length: | 420mm |
| Bulb/Tube material: | Inner: Glass, sodium resistant inner coating. Outer: Glass, indium oxide IR coating on inner surface. |
| Colour Temperature: | 1700K |
| Peak output wavelength: | 589nM |
| Total light output: | Unknown |
| Rated lifetime: | Unknown - 6000 hours estimated |
| Cap: | B22 |
| Operating voltage: | 70V |
| Operating current: | 600mA |
| Warmup/restrike time: | 12 minutes/intentanious |
| Cost (original): | Unknown |
| Value (now): | Unknown |
| Place of manufacture: | Shaw, England |
| Date of manufacture: | Unknown - Late 1980s to mid 1990s estimate |
| Current Status: | Failed. |
A good example here of a low pressure sodium lamp which has operated a long and useful life before eventually expiring of old age. There are two main ways that this type of lamp expire. The first being that the emitter material on the cathodes simply runs out, resulting in the striking voltage of the lamp rising beyond that available from the ballast. The second is the glass succumbing to attack by the hot sodium contained within - this is what has eventually killed this lamp
The outer jacket on these lamps is normally held under a hard vacuum to provide thermal insulation to the inner discharge vessel, so when this happens the low pressure neon gas fill from the arc tube escapes into the outer jacket. As this would lead to a situation where a discharge could be struck between the lead wires in the lamp base, essentially short-circuiting the ballast, a fuse is fitted in the lamp cap itself which will blow and isolate the metalwork in the lamp should this happen, preventing any damage to the ballast.
Osram SOX 35W Low Pressure Sodium Lamp - Note staining on arc tube from prolonged attack from sodium
Osram SOX 35W Low Pressure Sodium Lamp - Detail of lamp cap
Osram SOX 35W Low Pressure Sodium Lamp - Detail showing where the arc tube has failed near to one of the cathodes
Osram SOX 35W Low Pressure Sodium Lamp - Showing size of lamp
Osram SOX 35W Low Pressure Sodium Lamp - Detail of lamp crown, note metal disk which serves both as a heat reflector to keep the U-bend warm and to physically locate the arc tube
This page last updated:
19th June 2023: Changes to page formatting to improve readability on mobile devices, also made some background code changes to improve search engine behaviour.
