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I have a ballast that we are replacing in a church. There are approximately 12 dual lamp T12 Fixtures in parallel drops. The fixtures are all in line -- but L1, Neutral and Ground are parallel drops.

After 40 years some ballasts have failed - they are 4-wire magnetic type units. We have purchased 5 wire electronic ballasts to replace some. Upon replacing the first ballast, a GE magnetic ballast, with a Philips QuickPro 60 Electronic Ballast I managed to get a shock installing the lamp. I measured 50 VAC between the FRAME of the Fixture (my ground wire is attached to the frame), and the LAMP GLASS ITSELF - note the GLASS which is what I was touching when I got shocked - I was touching the middle of the lamp 6 feet in so I know I was not mistaken in what I touched.

I know I wired the new Ballast Correctly.

I have attached a picture showing the new Ballast wiring at the TOP of the image and the original magnetic ballast at the bottom of the picture.

My Question is two fold:

Since I have installed an electronic ballast and the other units in parallel have magnetic ballasts could this be causing an issue ?

What could be the problem that I am measuring this 50VAC between the glass and the frame of the fixture? Example of one Fixture NEW Ballast To Old Ballast Bottom - there are 12 fixtures of the old ballast style in a row - parallel drop

My examples of wiring are correct and I did find the culprit - I will post my answer.

SDsolar
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Ken
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1 Answers1

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After scratching my head - I decided to pull the tombstones out and inspect the wiring to make sure there was no sneaky connections and also nothing out of the ordinary. The older ballasts (original diagram are Magnetic Ballasts with PCB) the new ballast are electronic. I contacted the manufacturer and they suggested to verify my grounds for the ballast assembly. Since I had several that were fine and all inline - I verified ground from good unit to ground on unit that I was shocked with. Grounds were good.

So upon pulling the tombstones out and checking the wiring - I tugged on each of the wires, one of the wires just slid out of the connection. While it was inserted in the tombstone connection just fine; it just kind of slid out as if the spring clamp had not locked it in. I removed the wire and installed a new wire into the tombstone making sure it clamped down on the wire. After I had done this there was no longer an issue. I assume the wire was close enough to conduct but far enough away to cause the issue.

I do not understand that engineering wise - but maybe it has something to do with RF, High Voltage and an Air gap.

Ken
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