THIS IS A CLAMSHELL
Digital art I made of a clamshell which resembles a cobrahead. Actual photograph coming soon. Note that the refractor is a lot larger and the light housing above the refractor has a shape which is similar to that of the refractor. |
THIS IS A COBRAHEAD
This is a cobrahead streetlight which may look like a clamshell to some. Cobraheads can be identified by the fact that they look like a cobra spreading its hood when looked at from directly underneath. The refractor is much taller than the silver housing and is less circular than the clamshell. The light is much more streamlined and narrow. |
SEMI-CUTOFF
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FULL-CUTOFF
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This bucket light looks like it has a mercury vapour bulb... but believe it or not, this is a sodium bulb that's burning out.
When you believe you have spotted a mercury vapour light, watch it for at least two minutes. If it turns off or fades to orange, it's not a rare mercury vapour light, it's a sodium vapour light that's burning out. This pattern is a phenomenon that only really happens with sodium vapour bulbs called Cycling. The bulb starts taking in more voltage and turns itself off after a while. Then it turns back on and turns green like a mercury bulb and fades to orange, and then it repeats the process. |
Most streetlight bulb types and their wattage can be identified with their NEMA wattage labels. These are labels which identify the bulb type and wattage of a streetlight.
Learn more here: https://en.wikipedia.org/wiki/NEMA_wattage_label NEMA Wattage Label Bulb Type Colour Coding Blue: Mercury Vapour Yellow: Sodium Vapour Red: Metal Halide Red/White: Pulse-Start Metal Halide Grey: LED |
STEP 1
You found a historic streetlight - congratulations! Make a note of its location and find a computer and log into your Google Account (if you don't have one or want to make one, you can e-mail me to add the streetlight to the map for you). Then follow this link to access the map: https://www.google.com/maps/d/u/0/edit?mid=1oXhIzGxWBHqJBZ5eFAwnKI17z9PHV6WK&usp=sharing |