# High Pressure Sodium Lamp keeps blowing



## HARRY304E (Sep 15, 2010)

electricalcj said:


> We install 28- holophane fixtures with a 150W HPS Lamp on 240V. But one of the fixtures keeps blowing the lamp, instantly(3 seconds).
> 
> Could this be the mult-tap trans?



Yes and sounds like it is set for the wrong voltage.


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## electricalcj (Feb 9, 2011)

HARRY304E said:


> Yes and sounds like it is set for the wrong voltage.


Its tapped to the 240v leg like the rest.


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## HARRY304E (Sep 15, 2010)

electricalcj said:


> Its tapped to the 240v leg like the rest.



I would change the whole ballast and make sure there is no problem with the lamp socket .

Make sure you have 240 volts there as well there must be some reason this is happening.


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## John (Jan 22, 2007)

HARRY304E said:


> Yes and sounds like it is set for the wrong voltage.





electricalcj said:


> Its tapped to the 240v leg like the rest.


Like Harry said Plus....

27 worked and one didn't is pretty good odds for Chinese crap. I did a job one time where it was close to a 50% failure rate ...


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## HARRY304E (Sep 15, 2010)

John said:


> Like Harry said Plus....
> 
> 27 worked and one didn't is pretty good odds for Chinese crap. I did a job one time where it was close to a 50% failure rate ...


I did a job where all the high bays were fed with relock cable and the phases were mixed up from the factory so instead of getting 277 volts they were getting 480volts.

Need less to say we had about 8 lights blow in about 20seconds..lots of flames and smoke from those ballast...:laughing:


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## electricalcj (Feb 9, 2011)

HARRY304E said:


> I would change the whole ballast and make sure there is no problem with the lamp socket .
> 
> Make sure you have 240 volts there as well there must be some reason this is happening.


After the lamp blew, I took a 300V meter and measured the voltage at the socket. The reading was 1100-1400V, it was bouncing around everywhere. I figured, the reason for this reading was due my 300v meter max. But Regardless of the rating of my meter rating, I didn't get 240v.


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## John (Jan 22, 2007)

HARRY304E said:


> I did a job where all the high bays were fed with relock cable and the phases were mixed up from the factory so instead of getting 277 volts they were getting 480volts.
> 
> Need less to say we had about 8 lights blow in about 20seconds..lots of flames and smoke from those ballast...:laughing:


 
Every hear of the 48/48/4 rule?


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## crazyboy (Nov 8, 2008)

electricalcj said:


> After the lamp blew, I took a 300V meter and measured the voltage at the socket. The reading was 1100-1400V, it was bouncing around everywhere. I figured, the reason for this reading was due my 300v meter max. But Regardless of the rating of my meter rating, I didn't get 240v.


300v max meter :rollseyes: Did you disconnect the starter prior to testing it? If you have the right voltage coming in I would replace the ballast/starter/cap.


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