Over voltage in school

[DoinitforDale]

I am working on a HS auditorium installing LED retrofits in large overhead spotlights. Kits and drivers are rated for 120-277v. After installing them they began to burn out 1 by 1 after 30 minutes. Upon investigation my Klein meter tells me I have 299,300 volts at the point of connection. At the breaker source I’m reading 281 volts. Going to need a transformer to knock it down but want to know what would cause this in case it’s more widespread. Thanks

 

[petersonra]

Are you saying that the voltage gets higher as it goes farther downstream from the source of supply? That doesn't seem reasonable unless somebody installed a transformer to kick the voltage up.

 

[DoinitforDale]

I have found the issue, large remote ballast hidden behind a new air unit in a mechanical room that were suppling the previous metal halides

 

[Dennis Alwon]

Basically what Petersonra stated.... Feels good to find the solution...