Fluorescent fixtures ungrounded

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Old 03-11-15, 06:55 PM
Gen
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Fluorescent fixtures ungrounded

Hello, I've noticed over the years that ungrounded florescent fixtures tend to have short lives. Can anyone explain this to me? Thanks
 
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Old 03-11-15, 07:45 PM
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This is my take on the subject.....

For fluorescent lights to start working.... there is high voltage applied to the filaments or applied at both ends. The arc has to bridge both ends to start the ionization process but the arc can also bridge to the grounded reflector which will cause the bulb to start quicker.
 
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Old 03-12-15, 03:29 AM
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Likewise, it has been my experience that ungrounded fluorescent fixtures just don't work properly. Over time they will not come on unless you touch the bulb, etc. If the grounding wire is available, why not connect it properly? Takes just as much time to stuff it out of the way as it does to wrap it around a screw head.
 
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Old 03-12-15, 05:00 AM
Gen
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Well certainly I would attach a ground if it was there. It seems that the fixtures work OK for a while, then somehow the ballasts get degraded. I just know now....no more florescents in ungrounded conditions.
 
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Old 03-12-15, 09:50 AM
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There are conversion LED replacement bulbs that connect directly to power in and do not use the ballast. Their pricey but if yjr ballast is bad that would mitigate the price some. (If you look for them be sure you get the kind that connect straight to the AC. There is another kind that require no re wiring but they require a working ballast.)
 
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Old 03-12-15, 05:52 PM
Gen
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Yes thanks Ray, I plan to use the ballast-less LED florescents in the future.
 
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Old 03-14-15, 02:24 PM
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I find it interesting. First let me say I live in Wales so we have 230 volt supplies but on building sites we also use 55 - 0 - 55 which we call 110 volt.

Our fluorescent lamps are not designed for 110 volt so each one has an auto transformer to step up the voltage. I wanted to light a series of tunnels inside a nuclear power station and my boss said use fluorescent. So 16A supply lamps were 60W so should be able to supply around 30 but to be safe decided 25 was enough.

All worked fine for 2 hours then a report lights had failed. Clamp on ammeter and no wonder drawing around 22 amp. So started testing lamp in the workshop. Found a 60W could draw 0.8A each but the auto transformer was marked 110 - 0 - 127 volt so moved to using the 127 tapping and current dropped to 0.6A.

So back to tunnel and swapped to 127 volt and last 5 did not work so last 8 lamps set to 110 volt rest to 127 volt and all worked fine.

The problem in my case was two fold one being so close to the A station with 4 x 200 MW generators voltage to site was on the high side and also being in a tunnel and only using 110 volt and 2.5mm cable there was excessive volt drop.

It caught us out as normally we use 230 volt and volt drop is not so much of an issue. Today we would use HF ballasts so it would no longer be a problem but this was around 1992.
 
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