Metal Halide lights

[sd4524]

Learned something new yesterday the hard way. Now i want to know why. I was troubleshooting 175w metal halide wallpack. I tried 2 brand new lamps and neither worked. The new lamps were 150w metal halide. Not even a flicker, nothing from the 150w lamps.
So obviously to me, the ballast needs to be replaced. I replace the ballast (24 ft extension ladder) and try the 2 150w lamps. Nothing again! I talk with another electrician and he tells me that the lamp and ballast need to be identical to work. I run to supply house and get a 175w lamp but in the back of my mind I'm thinking he's wrong.
I installed the 175w and the light kicks right on! Nothing at all from a 150W? Not even a flickr? A quick burnout?
And before you ask, I'm working as an employee and did tell my boss what happened. It's up to him how he bills it. He said the same thing happened to him once.

 

[RyanA]

I think that the different ballasts, 150w, 175w etc all produce different secondary voltage. The lamps require a specific range to work in.

 

[480sparky]

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[hurk27]

You should always be replacing HID lamp like for like, never install a lamp that has different wattages or is of a different type, as doing so can cause ballast and or components to fail costing much more to repair.

Depending upon the ballast type and lamp, pulse start lamps will only ignite with a HV pulse, I think this pulse is about 1500 volts, installing a pulse start lamp in an older fixture will sometimes result in the lamp not firing, also be careful because some of those older 175 watt fixtures are not metal halide, they are Mercury vapor, while there are some multi-vapor lamp that will cross over and can be installed in both MH and MV fixtures installing a MH lamp in a MV fixture may or may not not ignite the lamp, also the wattage is very important, Installing a lower wattage lamp in a CWA ballasted fixture will result in much higher lamp current on the ballast and will cause it to fail.

never go by what someone had installed in a fixture when changing a HID lamp, always check what the fixture requires or check the ballast for lamp information.

Especially where you have non-electricians replacing lamps.

 

[sd4524]

Good stuff 480. Still not sure why I don't get a little bit of a glow.

 

[sd4524]

thanks hurk, we posted at same time. that helps to understand

 

[hurk27]

Good stuff 480. Still not sure why I don't get a little bit of a glow.

because HID lamps are an arc lamp, the require the right amount of voltage and energy to produce an arc through the mercury to vaporize it, to sustain an arc, each lamp of a different wattage and type will have its own requirements, voltage is set by the ballast as far as the supply goes, but the lamp will require a ballast that is designed for that lamp.

 

[jeremysterling]

Unless I know for sure what ballast lies beneath the belly pan, I will pull the cover to check the type and wattage. This past week, I opened a fixture labeled 400W that had been refitted with 1000W ballast and lamp.

It seems like there are a lot of people with a bucket truck or lift who put whatever convenient lamp that may fit the socket (or may not fit as with pulse start rejection lamps and sockets, I've seen it done).

 

[LarryFine]

never go by what someone had installed in a fixture when changing a HID lamp, always check what the fixture requires or check the ballast for lamp information.

Especially where you have non-electricians replacing lamps.

Unless I know for sure what ballast lies beneath the belly pan, I will pull the cover to check the type and wattage. This past week, I opened a fixture labeled 400W that had been refitted with 1000W ballast and lamp.

It seems like there are a lot of people with a bucket truck or lift who put whatever convenient lamp that may fit the socket (or may not fit as with pulse start rejection lamps and sockets, I've seen it done).

In my opinion, both of these posts apply equally well in the T-12 vs T-8 ballast-matching thread.

 

[norcal]

The 150W MH are pulse start & I would assume the 175W were not which would be another reason they would not work.

 

[stevebea]

You should always be replacing HID lamp like for like, never install a lamp that has different wattages or is of a different type, as doing so can cause ballast and or components to fail costing much more to repair.

Depending upon the ballast type and lamp, pulse start lamps will only ignite with a HV pulse, I think this pulse is about 1500 volts, installing a pulse start lamp in an older fixture will sometimes result in the lamp not firing, also be careful because some of those older 175 watt fixtures are not metal halide, they are Mercury vapor, while there are some multi-vapor lamp that will cross over and can be installed in both MH and MV fixtures installing a MH lamp in a MV fixture may or may not not ignite the lamp, also the wattage is very important, Installing a lower wattage lamp in a CWA ballasted fixture will result in much higher lamp current on the ballast and will cause it to fail.

never go by what someone had installed in a fixture when changing a HID lamp, always check what the fixture requires or check the ballast for lamp information.

Especially where you have non-electricians replacing lamps.

Pulse start is is 3-5kv depending on the fixture. Older MH and newer PS of the same wattage in the same facility where they dont have qualified personnel is very confusing. I have a facility where I do work with this situation and they are always mixing lamps.

 

[TomChamp]

Pulse Start vs. Probe Start

Pulse Start vs. Probe Start

A Probe Start lamp will work in a Pulse-Start fixture, A Pulse-Start lamp will not work in a Probe Start fixture. A Pulse-Start lamp has two probes one on each end of the arc tube, thus requires a starter/ignitor. A Probe Start has two probes on the lower end of the arc tube and one at the top. My guess is the 175W is Probe Start and the two 150W lamps you tried were Pulse Start. The new lamp (175W) was Probe Start. Does the fixture have a starter/ignitor?

 

[CNC]

All MH lamps smaller then 175w have ignitors.

 

[broadgage]

Use of the wrong wattage lamp is unwise, and could be considered to be a code violation (use equipment according to the manufactuerers instructions etc)
That said, I would normally expect a 150 watt lamp to work, at least to an extent, on a 175 watt ballast.
Some metal halide lamps require a high starting voltage from a starter or ignitor built into the fixture, others have a starting device built into the lamp.
I would consider it lekely that the fixture in question has no starting circuit, but requires lamps with an integral starter.
Presumably the correct 175 watt lamp incorporated a starter but the 150 watt lamps did not.

 

[CNC]

Check this out.

http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/mwmhl/differenceProbePulse.asp

 

[NJKen]

A Probe Start lamp will work in a Pulse-Start fixture, A Pulse-Start lamp will not work in a Probe Start fixture. A Pulse-Start lamp has two probes one on each end of the arc tube, thus requires a starter/ignitor. A Probe Start has two probes on the lower end of the arc tube and one at the top. My guess is the 175W is Probe Start and the two 150W lamps you tried were Pulse Start. The new lamp (175W) was Probe Start. Does the fixture have a starter/ignitor?

Not quite true. A probe start lamp has a resistor and bimetalic spring in it. These two devices will kill and ignitor. On some ocasions the ignitor will win and blow the bimetalic spring off but thats not a chance i like to take.
Ken

 

[TomChamp]

Not quite true. A probe start lamp has a resistor and bimetalic spring in it. These two devices will kill and ignitor. On some ocasions the ignitor will win and blow the bimetalic spring off but thats not a chance i like to take.
Ken

I didn't mean to imply it was OK to use a probe start lamp in a pulse start system, I was just pointing out that it will light. For how long? Who knows.

 

[jmellc]

You should always be replacing HID lamp like for like, never install a lamp that has different wattages or is of a different type, as doing so can cause ballast and or components to fail costing much more to repair.

Depending upon the ballast type and lamp, pulse start lamps will only ignite with a HV pulse, I think this pulse is about 1500 volts, installing a pulse start lamp in an older fixture will sometimes result in the lamp not firing, also be careful because some of those older 175 watt fixtures are not metal halide, they are Mercury vapor, while there are some multi-vapor lamp that will cross over and can be installed in both MH and MV fixtures installing a MH lamp in a MV fixture may or may not not ignite the lamp, also the wattage is very important, Installing a lower wattage lamp in a CWA ballasted fixture will result in much higher lamp current on the ballast and will cause it to fail.

never go by what someone had installed in a fixture when changing a HID lamp, always check what the fixture requires or check the ballast for lamp information.

Especially where you have non-electricians replacing lamps.

I hate that a lot of labels have burned off the fixtures or weathered to the point of being illegible. If you have a long row of 175's, no problem, you just know. If you're somewhere that each one is different, it's a mess.