That is fantastic! It is always a shame that usually at least one GEC brick would be casually replaced by a MA60, thus defeating the purpose of full cut-off lighting around airports!

The later Philips family of low pressure sodium lanterns (the MA50, MA60 and MA90) can also be configured to give a cut-off optical distribution. It requires the installer to move the bulbholder further into the canopy of the lantern - positions are clearly marked. However, this requires the installer to have the knowledge to do so...

All the best,
Simon

Yes, though some of the Bricks might as well not be cut-off, considering some have turned on their brackets! Would be great to see some photos of these if anyone's fairly local

_________________
"I used to rule the world... Now I sweep the streets I used to own."
Remembering GEC.

I'm glad that Philips do not market their MA series/SRS201s as full cut-off lanterns as, thanks to their shallow U-shaped bowls, such a claim would be a blatant lie!

Of the two types of lantern (the GEC brick and the Philips SRS series) the GEC brick can claim to be the only truly full cut-off SOX lantern, but only when it's fitted with the flat-glass panel. The GEC bricks with the bowls that protrude below the canopy will still leak some light above the horizon.

I'm glad you mentioned those! I never really saw the point of the bowled GEC Bricks as wasn't the design of the Brick meant to be primarily for use where full cut-off was necessary eg, next to railway lines and airports? Didn't providing a bowled option defeat the object somewhat?  

The GEC Catalogue states "cutoff" with high downward light output ratio of up to 73%.

They did.

Philips Street Lighting Catalogue, Roadlighting, Circa 1976, "MA SOX Range"

Second sentence: "Unique optics provide both 'cut-off' and 'semi cut-off' distribution in one lantern."

What's your definition of "cut off?" I think there might be some confusion here.

All the best,
Simon

My assumed definition is no light above the horizontal plane of the lantern.

How I see it as, is basically a lantern which has flat glass as apposed to a bowl.

_________________
From streetlighting to radio, dance through the night whilst the streetlights are glowing outside.

Well by that definition, a Philips MA definitely couldn't be a full cut-off lantern no matter where you set the lamp in it!