STREET LIGHTING EQUIPMENT
VARIATIONS IN FOCUSING OF "WEMBLEY"
REFRACTOR LANTERNS
EFFECT UPON ILLUMINATION (FOOT-CANDLES) AND
ROAD BRIGHTNESS
Note that the high focus gives half the test point illumination on horizontal test plate, but double the effective road brightness.
Rferrign to the Ministry of Transport Departmental Interim Report on Street Lighting, it will be noted that "Pools of Darkness"
are on of the least desirable forms of street lighting.
The G.E.C. "Wembley" lanterns fitted with English-made refractors are easily focusable with an external focusing control so
that patchiness can be eliminated in a few minutes by the simple operation of turning a single knob.
RESULTS OF TESTS ON THE ABOVE INSTALLATION AT BARNES.
|
|
Left-hand side
of road. | Right-hand side
of road. |
| Spacing in feet | 150 | 150 |
| Lantern height in feet | 25 | 25 |
| Type of Lantern | Z 5022 "Wembley" non-axial asymmetric Refractor |
| Type of Lamp | 500W OSRAM | 500W OSRAM |
| Angle of peak candle power | 85° | 72° |
| Service test point illumination (Carriageway) | 0.08 F.C. | 0.16 F.C. |
| Diversity of illumination (Carriageway) | 11 to 1 | 5½ to 1 |
| Effective road brightness (From carriageway) | 0.6 e.f.c | 0.3 e.f.c |
| Diversity of road brightness | 2 to 1 | 4 to 1 |
| B.S.I. Class of installation | E | D |
| Road appearance (see photograph) | Good | Patchy |
Back to: GEC Street Lighting
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