Switching Light Fixtures

Low pressure Sodium will give you 165 lumens per watt, a 500k T5 will give you only 104, a 4100k T8 will give you 90 and a clear metal halde gives you 85 lumens per watt.

Since the light fixtures are available in standard wattages, replacing one with another type in your specific case will give you additional light intensity but no saving in electrical energy.

When you claim that current output from the existing two metal halides adequately serves your requirement, simple and straight answer is; DO NOT CHANGE.

I guess a little background information is needed. The metal halide wall packs that are installed are from the original build date 20 years ago. Over that time, the polycarbonate lenses have been fried to a crisp and yellowed from the UV. After searching high and low, there is not a replacement for just the lense, therefore if I must change out the wall pack, if I want to remove the lenses which is my opinion is imperative. I want to ensure that I am going the most energy efficient way. Make sense?

Makes sense to me. To my previous post I'll add that you can buy polycarbonate sheet material from the big box home improvement stores and make your own replacement lenses. Polycarbonate is easy to work with, so long as you use slow speed saws and slow speed drilling, and keep the cutting edge lubed. You might just use a hole saw to remove a yellowed section from the center of the lens and chemically weld a disk of polycarbonate over the hole you made.

If you decide to replace the metal halide lamps, be sure you use fixtures that are OK to use in wet environments.

http://www.google.co.uk/search?q=commercial+US+exterior+light+bulb+effiecenty&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&rlz=1I7GGLT_en&redir_esc=&ei=xQ2uTPpv3c2MB-izlFA

http://www.google.co.uk/search?q=commercial+exterior+light+bulb+effiecenty&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&rlz=1I7GGLT_en&redir_esc=&ei=Ww2uTKn9Ds2TjAe_pM1M

http://www.google.co.uk/search?q=most+efficent+water+proof++lamps+in++US+&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&rlz=1I7GGLT_en&redir_esc=&ei=zQ6uTIvPO8yNjAfY0e0_

none of these links are mine

Metal Halide lamp & Fluorescent tubes (T5 or T8) are all in the same category of energy efficiency. As such by way of source efficiency, there will not be any substancial change towards "decent energy savings".

Coming to the other aspect of the ageing of the lamp, yellowing of polycarbonate enclosure, detrioration of the reflecting surfaces etc., decision has to be taken on the basis of physical condition.

If the mounting height of the fitting is more than 11 feet or 3.5 meters then existing metal halide fitting would be the better alternative in comparison with the proposed T5 of T8.

Unfortunately you are in USA. If you were in India- I would have come down and demonstrated a solution- which gives same light out put in lumen and yet saves energy by nearly 40%. Yes, there are more energy efficient solutions even for metal halide lamps.

Why don't you go for LED lighting. The equivalent LED luminaire will be about 70W which will give you decent savings to the extent of more than 60%. The only issue is the cost. These are very costly. May be in US they are not as costly as here in India. But they have long life, good CRI (colour rendering index) and above all are eco-friendly. You can choose cool white light corresponding to 6000-6500K colour temperature. The quantity can be decided by the illumination level you wish to have (= the existing level). The existing level can be found by using a lux meter. Suppose the exiting illumination level in your bay is 300 lux with the existing 2 X 175 W MH lamps. A lighting expert will be able to tell you how many numbers of 70W LED luminaires will be required. A bit of cost benefit analysis is required. Worth an exercise, I think.

Good luck. Let us know what you settled for.

BB Raina

LED is a very much hyped up bad alternative. All claims of manufacturers and marketing people are bogus. There have been discussions on this subject earlier in CR 4 on this alternative. Don' waste your money and time experiment with this.

I wanted to attach a few pictures of actual installation - before and after repalcement of HPSV & MH lamps. the camera icon button seems missing now a days on CR 4!??? I do not know why - admins to kindly see.

You have had some good advice already but let me add some of my own. Firstly if you are going to stay with Metal halide lamps and there is no reason not to than make sure of the following. Buy a suitable luminaire with a Borosilicate or toughened glass cover/lens(for thermal shock) as opposed to a PC( polycarbonate) cover: these will not be attacked by the UV in the lamps and yellow. This includes UV stop metal halide lamps, which although better than the older type lamps still release some UV. Detergents also attack PC and can cause yellowing. Buy the new luminaire with an electronic ballast,these devices are more energy efficient than the conventional core and coil type control gear and have a very good power factor. You can also consider using a 150W metal halide lamp instead of the 175W units a number of manufacturers have 150W lamps that give more light than the older 175W lamps. Note T5 lamps are made for hot operation +35deg C air temperature and do not work well or give their best light output in cold environments such as open ended car washes in winter. Metal halide lamps operating temperatures are far wider.

http://www.tigergreen.com/

Take a look at Tiger Green. They may be able to help. Cost is expensive but life is long. Payback is usually about 3 yrs. for part time operation. About 1 yr. for 24/7 lighting. (According to them :-))

The best option would be to go with a 6 lamp t5 fixture, It will have to be a HO (high output ) for the cold conditions,

This is to the CR4 administrator - why the camera button icon has been removed? How can we attach diagrams, photos?

If you are a Guest, you cannot post pictures. The system has no way to know that you are a member unless you log in.

Thanks. Kindly see pictures of new generation lamp rated at 150 W replacing 250 W MH and SV lamp. These have been installed in a factory in Pune, India. The lamps are rated for maintaining lumen at near 80% of its original fro 60 to 70 K hours. can fill tonnes of information on why LEDs will never take off and it is only hyped up. MH lamps take 5 to 10 mnts to turn on again after a short power failure of even 0.1 sec. Even SV takes about 30 to 40 sec to cool and turn on. Not so with these lamps. You can stare at the lamp and not get blinded(like LEDs) Kindly see these lamps replaced in same position at same height after removing old ones and see the comfort on the eyes.

I had to delete one picture as uploading was taking infinite time.