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-   -   Metal halide lamp (http://www.diychatroom.com/f18/metal-halide-lamp-15638/)

Richo 01-15-2008 11:23 AM

Metal halide lamp
 
Hi,

I just took down 2 burned out lamps from outdoor light fixtures at the building I work at. The lamp is a standard base 70W metal halide lamp. Replacements for these seem to be quite expensive and probably not easy to find locally.

What exactly is the purpose for having such an uncommon type of bulb in this type of fixture?

Could this bulb possibly be replaced with a standard base outdoor rated flourescent? Although the bulb doesn't show a voltage rating I would have to assume that being a standard screw base it is going to be 120 V.

Thanks for your help.

perpetual98 01-15-2008 11:30 AM

It's most likely 120V. You can replace it as long as you make sure that you get the ballast removed as well. Ballasts are very specific their bulbs. If you replace it with fluorescent, you'll have to match the new bulb to a new ballast. Going incandescent/CFL will be your quickest route I bet. To be on the safe side, you can check the incoming voltage to the ballast with a multimeter, but I'd be shocked (pun intended) if they were running 220V to that fixture.

220/221 01-15-2008 12:39 PM

Quote:

Replacements for these seem to be quite expensive and probably not easy to find locally




It is a standard lamp and it's a good lamp. Not at all hard to find.

Just put a new one in and you will be good for several years. If you remove the ballast and go to an incandescant you will be sacrificing lumens and changing the lamps several times a year.

Quote:

I would have to assume that being a standard screw base it is going to be 120 V.


Boneheads that assume things like this should be slapped. The supply voltage to the fixture may be 120v but the voltage is changed in the ballast. The voltage at the lamp socket is completely different.

Don't start retrofitting things. Keep it simple and put the right lamp in. Don't assume anything

Richo 01-15-2008 12:54 PM

Quote:

Boneheads that assume things like this should be slapped.
I take offense to being classified with the "boneheads" as I would never just stick another lamp in the socket without actually testing the socket voltage first. Some people might do that but I wouldn't.

Because I had never seen one of these before I was thinking that it might be hard to find at the local home center, but I will give them a call.

Thanks for your help.

Big Bob 01-15-2008 01:50 PM

You may have better luck at an electrical distributor (supply house) or even the internet. Just take the lamp with you. Merury Vapor will run off the MH ballast. But not visa versa. You will be better off with the MH lamp that the fixture is designed for.

Good luck!

Richo 01-15-2008 02:24 PM

Actually I did find these at the local home center. Because I had never bought one before or heard of it for that matter, I figured it was something that was used primarily in commercial applications and I didn't think it would be common enough to find there. I guess you just never know.

Thanks :thumbsup:

AllanJ 01-15-2008 03:11 PM

Quote:

Originally Posted by Richo (Post 88667)
What exactly is the purpose for having such an uncommon type of bulb in this type of fixture?.

It's more energy efficient.

The fixture as it stands can only have the same kind of lamp put in it.

120 volt metal halide fixtures are available and can be used for home use too. Metal halide gives a more pleasing light than mercury or sodium while giving about four times the light per watt compared with incandescent.

Quote:

Originally Posted by Richo (Post 88667)
I would have to assume that being a standard screw base it is going to be 120 V.

Historically the "standard" screw base, known as medium screw base, has been used for lamps under about 250 watts. The next larger size, mogul screw base, has been used for lamps above that. This has to do with heat dissipation, particularly for incandescent lamps mounted base up. The smaller sizes like candelabra screw base (C-7 Christmas lights) were meant for decorative lighting with smaller infrastructure and they also have maximum wattage ratings, I think 100 for that size.

220/221 01-16-2008 12:39 AM

Quote:

I take offense to being classified with the "boneheads"

Don't be so sensitive. :wink: You are in good company.

How many of us can honestly say that we haven't shown some bonehead behavior in our years?:laughing:

Not me, that's for sure.:jester:

You gotta understand that I have pulled MANY A lamps out of HID fixtures over the years and I always shake my head. :no:

frenchelectrican 01-16-2008 01:37 AM

Quote:

Originally Posted by 220/221 (Post 88861)

You gotta understand that I have pulled MANY A lamps out of HID fixtures over the years and I always shake my head. :no:


Yepper i did see the same thing and few case i did see some of the A type lamps actally did expoled just once but rest useally get screwed up fast lol.

Merci, Marc

mtm 01-16-2008 09:27 AM

not so hard to find

http://www.1000bulbs.com/70-Watt-Met...e-Light-Bulbs/

Buzzbob 01-19-2008 04:11 PM

On a similar vein, I have a 10 year old post light that I purchased through a supply house and had an electrician wire the ballast etc. I had a MH bulb in it for years. When it finally burned out I replaced it with a mercury vapor and it flickered a bit but worked for a few years. I decided to go back to a MH bulb and the first night it worked great. The second night it turned itself off and on. The third night it was blown.

I pulled the fixture off the post (which I had never done before) and it was labeled "Incandescent only"! I can't see a model # or any info on the ballast located inside the post. Now I don't know what kind of bulb to put in there!

Any advice?

Bob

220/221 01-19-2008 05:09 PM

Quote:

Any advice?

You knowingly put the wrong lamp in?:whistling2:

You got your moneys worth out of it :yes: Get a new fixture.

J. V. 01-20-2008 10:19 AM

HID Fixture inputs can be as high as 480 volts. You may even run into 575 in old textile mills.
Trying to check voltage at the screw base of this lamp is not a good idea and will tell you nothing. It also could knock the "you know what" out of you or flash on you. The ballast will tell you everything you need to know. It's really quite simple. Look at the bulb and write down the specs. Look at the ballast and verify the correct bulb is in the fixture. Go to the store and buy a bulb. If the bulb does not correct the problem go and get a rebuild kit or new fixture. You now have the new bulb too.

AllanJ 01-20-2008 02:37 PM

Quote:

Originally Posted by Buzzbob (Post 89996)
On a similar vein, I have a 10 year old post light that I purchased through a supply house and had an electrician wire the ballast etc. I had a MH bulb in it for years. When it finally burned out I replaced it with a mercury vapor and it flickered a bit but worked for a few years. I decided to go back to a MH bulb and the first night it worked great. The second night it turned itself off and on. The third night it was blown.

I pulled the fixture off the post (which I had never done before) and it was labeled "Incandescent only"! I can't see a model # or any info on the ballast located inside the post. Now I don't know what kind of bulb to put in there!

Are you sure you put the same kind of MH bulb in the third time as the first?

Any incandescent fixture can be converted for MH or other kind of bulb by having a ballast sold separately installed. Your electrician might not have peeled off the "incandescent only" sticker when he added a ballast.

An incorrect bulb can cause deterioration of the fixture mounted ballast and later installation of the right bulb gives you problems. When the bulb blinks on and off numerous times in quick succession (sodium bulbs on their last legs are notorious for this) this deteriorates the ballast too.

(For those eavesdropping) Sometimes the ballast is part of the bulb (self-ballasting) rather than part of or next to the fixture. If you replace a self-ballasting bulb with a non-self-ballasting bulb, you end up with no ballast and the bulb blows in short order.


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