HP sodium Lighting [RE-wrenches]

[Travis Creswell, Ozark Solar]

Hi Ray,

If you could, I'd avoid HPS and especially avoid LPS.  Yes, it does have the
highest lumens per watt (LPW) but LPW does not completely reflect what our
eyes see.

Color Rendering Index and Kelvin are also very important.  A CRI of 100 is
perfect. IE; 100 out of 100 people will say they like it, halogen is the
typical benchmark.  And it turns out that we feel the brightest light is
somewhere around 5000 Kelvin.  HPS is approximately 2800 Kelvin with a CRI
of less then 40.  IE less then 40 will approve of it.  The classic "cool
white" fluorescent lamp is 4100 Kelvin and ~60 CRI and warm white is 3000k
and ~60 CRI.

When you get into the tri-phosphor fluorescent the CRI approaches 90.

So what I am trying to say is people will actually think a 35 watt
fluorescent is brighter then a 35 w HPS and that's what matters.  I've done
hundreds of side by side comparisons for customers and every time they
choose the fluorescent. A foot candle meter will say the opposite but it's
not signing the checks, the customer is, so guess which one I pay more
attention to.

In case you haven't figured out we do a ton of commercial and industrial
lighting design and installation. (non-solar stuff)


I don't know about requiring pure sine wave.

The HID (high intensity discharge, HPS, MH, MV, ETC) ballasts I've measured
have no start up surge.  As the light warms up the current climbs to it's
rated running current.

The HPS lamps in that size range are likely more expensive to replace than
fluorescent.

Best,

Travis Creswell
Ozark Energy Services







-----Original Message-----
From: Ray Walters [mailto:walters at taosnet.com] 
Sent: Wednesday, February 01, 2006 3:27 PM
To: RE-wrenches at topica.com
Subject: HP sodium Lighting [RE-wrenches]

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Hi Wrenches;

I'm doing a small lighting project for the University of New Mexico. It 
will be a demonstration for future students, as well as a hands-on 
installation for my current class. We are proposing using Bollard type ( 
3 ft pedestal lights for along sidewalks, etc.). The only reasonably 
priced units are AC, and are High pressure Sodium. HPS lighting is as 
efficient or more so than fluorescents, but I'm concerned about  the 
inverter for HPS lighting. MY questions:
1) Do HP sodium light ballasts require pure sine wave?
2) How much surge capacity do their ballasts require to start (35 watt 
light), worst case scenario, ie.  very cold, very hot, etc.
3) Anybody have a good source for DC bollards maybe?

We found a site that had DC LED Bollards (wow!) but alas it was european 
and not available here.

Thanks for sharing your wealth of knowledge,

Ray Walters