HID MAGNETIC BALLAST

[VTP99]

So I found something of interest yesterday
while servicing some parking lot lights utilizing 480v service. A single pole with 4 fixtures and a ballast in each fixture. Typically they are wired 480 to each ballast. Here I found where someone had wired 2 ballast in series across the 480 volts. All 4 fixtures were wired this way. Two and two. Has anyone seen this done. Is it allowed and why ? Personally in over 35 years I have NEVER seen this done. What say you all ?

[BBeerme]

Maybe someone had a bunch of 240 ballasts hanging around. Or got them at a great price.

Can't imagine it would be a code violation, not like you're messing around using a ground to carry current or something like that. Probably need to have Timebuilder stop by to weigh in.

[VTP99]

Pretty sure they were multi tap with a 480 tap. I'll have to grab one off the truck. Your thinking could be correct though. Question is if one ballast goes bad how would that affect the second ?

[BBeerme]

Heh heh, that would depend. If one of the series ballasts internally shorted, then it would take out the other one. If it failed open, then the second ballast would not be harmed.

Pretty sure they were multi tap with a 480 tap. I'll have to grab one off the truck. Your thinking could be correct though. Question is if one ballast goes bad how would that affect the second ?

[VTP99]

Hahaha....I should have used the 120v taps and put all four in series, hehe

[buttwheat]

No disrespect meant at all but why are you servicing lights? Are you a licensed electrician? Do you work a facilities job?

[VTP99]

No disrespect meant at all but why are you servicing lights? Are you a licensed electrician? Do you work a facilities job?

Been servicing electric signs and lights for about 40 years now. That and I have the equipment to do said work. I've installed high rise signs 80' tall next to 4 lane highways.

[VTP99]

Maybe someone had a bunch of 240 ballasts hanging around. Or got them at a great price.
.

Well BBeerme, you hit the nail on the head. I just checked the ballast and the taps are 120/208/240/277 no 480 tap.
Maybe you should consider a career in criminal investigation

[BBeerme]

I sort of already have one. Isn't that one of the things we do? We look at the evidence left behind after a failure, perform our forensic investigation and "once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth."

Well BBeerme, you hit the nail on the head. I just checked the ballast and the taps are 120/208/240/277 no 480 tap.
Maybe you should consider a career in criminal investigation

[VTP99]

So my only question left is this an acceptable practice and in violation of any NEC code ?

[BBeerme]

I'm guessing no, but give a shout out to Timebuilder. Send him a link to the thread in a PM.

So my only question left is this an acceptable practice and in violation of any NEC code ?

[VTP99]

We'll see if he chimes in. If not I'll give a shout out.
I just have to know if I need this trick in my bag...

[wolfdog]

NEC 410.74 says that the luminaire has to be labeled for the voltage used. The ballasts were not listed for 480 volts
There are probably others but that one comes to mind.