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[DSLF] Digest Number 1374
There are 4 messages in this issue.
Topics in this digest:
1. Crime in Des Moines Declines After Streetlights Turned Off
From: Steve Pauley <spauley@cox-internet...>
2. Re: Crime in Des Moines Declines After Streetlights Turned Off
From: "David Oesper" <oesper@aol...>
3. RE: Re: Crime in Des Moines Declines After Streetlights Turned Off
From: "friedel.pas@bvpartners..." <friedel.pas@bvpartners...>
4. IESNA Luminaire Cutoff Classifications - refresher
From: "David Penasa" <dpenasa@unm...>
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Message: 1
Date: Sun, 06 Jun 2004 16:08:08 -0600
From: Steve Pauley <spauley@cox-internet...>
Subject: Crime in Des Moines Declines After Streetlights Turned Off
> From: "David Oesper" <oesper@aol...>
>Subject: Crime in Des Moines Declines After Streetlights Turned Off
http://www.dmregister.com/apps/pbcs.dll/article?AID=/20040605/NEWS05/406050341/1\001/NEWS
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Dave
Thanks for this article. I have combined it with a .jpg picture
of a drop lens to fco re-fit and sent it with a message to many on my
dark skies email list. My message is that we don't want to
turn out the street lights, just convert drop lens lights to fco.
It is clear that this move still makes many people feel
uneasy and fearful. Maybe the compromise is to use
a lower wattage fco fixture when resurrecting a darkened
light. It is a perfect chance to educate and begin such
re-fits when needed.
Steve
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Message: 2
Date: Mon, 07 Jun 2004 06:41:39 -0000
From: "David Oesper" <oesper@aol...>
Subject: Re: Crime in Des Moines Declines After Streetlights Turned Off
Steve Pauley wrote:
>It is clear that this move still makes many people feel
>uneasy and fearful. Maybe the compromise is to use
>a lower wattage fco fixture when resurrecting a darkened
>light. It is a perfect chance to educate and begin such
>re-fits when needed.
Yes, I agree, but therein lies the rub. In typical knee-jerk fashion
the City of Des Moines is looking to save a quick buck by turning off
streetlights, when what they really should be doing is investing in
full-cutoff fixtures with lower-wattage bulbs where possible. For
example, they could have changed to full-cutoff, lowered the wattage,
and left *all* the lights on. But nobody wants to "spend money to
save money" and so the solution is less than ideal.
Even when full-cutoff fixtures are already in use, there's a problem
(and this is a big problem with HID fixtures): you can't just unscrew
the bulb and put in a lower-wattage one like you can with incandescent
and fluorescent lights. You have to change out the ballast, too, and
that usually means changing out the whole fixture. Now we're talking
real money.
Wouldn't it be great if someone developed a "universal ballast" that
could be used for several wattages of bulbs?
Best Regards,
David Oesper
Ames, Iowa
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Message: 3
Date: Mon, 7 Jun 2004 02:58:16 -0400
From: "friedel.pas@bvpartners..." <friedel.pas@bvpartners...>
Subject: RE: Re: Crime in Des Moines Declines After Streetlights Turned Off
Oorspronkelijk Bericht:
-----------------
Van: David Oesper oesper@aol...
Datum: Mon, 07 Jun 2004 06:41:39 -0000
Aan: DarkSky-list@yahoogroups...
Onderwerp: [DSLF] Re: Crime in Des Moines Declines After Streetlights
Turned Off
Wouldn't it be great if someone developed a "universal ballast" that
could be used for several wattages of bulbs?
Best Regards,
David Oesper
Ames, Iowa
Such balast exists in an other way. there are systems where you can dim the
light in an electronical way. When diming the light with 50% you save
energy but less then 50%, but the saving is noticible (I think it was about
40% but I'm not sure). With some systems the lifetime of the bulb can be
exchanged with 1/3. And there are also other benifits: You can haven just
the right luminance that you want on the road, change the level of the
luminance depending on the situation on the road, trafic itensity and
weather conditions. Together with less of cost. I'm sure that this will be
an important technology for the future.
Regards,
Friedel
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Message: 4
Date: Mon, 7 Jun 2004 09:55:28 -0600
From: "David Penasa" <dpenasa@unm...>
Subject: IESNA Luminaire Cutoff Classifications - refresher
Various cutoff classification terms are often used on this list forum. I
thought it might be helpful to again publish the official definitions used
in IESNA documents.
The following definitions are from pages 6-7 of IESNA RP-8-00 Roadway
Lighting. Note that definitions are also given on page 7-8 of the IESNA
Handbook (Ninth Ed has errata which corrects the definitions) and pages 17
and 19 of RP-33-99 Lighting for Exterior Environments (definitions are
incorrect as they are missing text "or above" in various locations within
the definitions)
Full Cutoff: A luminaire light distribution where zero candela intensity
occurs at or above an angle of 90 degrees above nadir. Additionally, the
candela per 1000 lamp lumens does not numerically exceed 100 (10 percent) at
or above a vertical angle of 80 degrees above nadir. This applies to all
lateral angles around the luminaire.
Cutoff: A luminaire light distribution where the candela per 1000 lamp
lumens does not numerically exceed 25 (2.5 percent) at or above an angle of
90 degrees above nadir, and 100 (10 percent) at or above a vertical angle of
80 degrees above nadir. This applies to all lateral angles around the
luminaire.
Semicutoff: A luminaire light distribution where the candela per 1000 lamp
lumens does not numerically exceed 50 (5 percent) at or above an angle of 90
degrees above nadir, and 200 (20 percent) at or above a vertical angle of 80
degrees above nadir. This applies to all lateral angles around the
luminaire.
Noncutoff: A luminaire light distribution where there is no candela
limitation in the zone above maximum candela.
David
********** El Servicio Real **********
David A. Penasa, PE dpenasa@unm...
University Facilities Engineer - Electrical
The University of New Mexico
PPD - Engineering & Construction
(505) 277-1141 / FAX (505) 277-2385
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