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" Euro " electrician
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We installed a new outdoor lighted sign 11-12-2012. It was built with one high output ballast and eight GE F42T12D-HO daylight 800 tubes. One tube was broken during shipment, so we left the socket furthest from the ballast empty. All the tubes lighted up fine. I went to replace the tube today 12-18-2012 and noticed the tube next to the empty socket was dimmer than the rest and was blackened about 2 inches up the tube from the end. The tubes are spring loaded, but I seated the tube again to check for proper seating in the socket. The tubes have a plastic rim around the pins, so seems hard to not seat properly. What do you think is the cause of this tube burning so soon. The rest of the tubes look and work fine. Another thing I noticed while putting the tube in was that I felt a tingle on my hand that touched the metal frame of the sign. The light was on, I pushed the tube into the spring loaded socket and then into the other socket. In the process, both hands were holding the tube, but the back of one of my fingers touched the metal frame and I felt the tingle :huh: It happened when working with both tubes. Was that just energy flowing from the tube itself or what? Thanks for any help or suggestions. :confused1:
The major issue with the HO's like the sign ballast that is a rapid start set up so you will need each pair of lamps to get one part working ( you may noticed in the diagram ) so leave one off it will foruce the second bulb to keep in preheating mode without strikeing a arc across the tube.

8 lamp ballast is not a common format unless I assumed that you have pairs of 42T12-HO in series then I can safely say that you have 4 lamp ballast but please do correct me if I am wrong.

The other thing the open circuit voltage on sign ballast is much higher than conventail HO ballast is they useally run anywhere from 500 to 750 volts range depending on ballast design ( convental HO ballast usally run about 380 volts )

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