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Led Tube T8 Retrofit: Single-Ended vs. Double-Ended
Date:2019-03-20 Source：http://gielight.com provenance:admin
In order to reduce material and labor costs, a preferred way of replacing inefficient 32W T8 lamps is by removing them and installing ~17W LED tubes. These LEDs can come in several configurations.
The first configuration involves simply replacing the tube and reusing the existing electronic ballast. In this case initial manual labor is involved but the ballast would still require maintenance after its rated hours.
The second configuration is single-ended power and using an external ballast/driver.
A third configuration is single-ended power with no ballast needed.
Single-ended vs. double-ended:
Existing fluorescent lamps are typically double-ended power, meaning one side of the feed is hot and the other side neutral. The contact where the lamp is held in place is called the tombstone. Fluorescents use shunted tombstones, so that the two contacts on one side of the lamp are shorted together with no voltage difference between them.
The single-ended LED retrofit tubes with no ballast needed require the installation of non-shunted tombstones on one side of the lamp. In that case, hot and neutral are on the same side of the lamp.
I cannot figure out why manufacturers would not sell double-ended LED tubes that do not require a ballast, so that a bit less labor would be required in the replacement. They could just run the neutral back to the second end after passing the last LED on its return path. The shunted tombstones could be reused in that case.
It seems like safety is a concern but I can't find definitive explanations. Anybody have an idea?
If there are double-ended power LED retrofit tubes out there that don't require an external driver or existing ballast, please point me in the right direction. The only labor required in that case would be removing the ballast and rewiring. Then no periodic ballast maintenance would be required.
Please provide thoughts.
In the previous：
4 Types Of LED Tubes: Type A, Type B, Type C And Type A+B
The next article：
Shunted vs Non-Shunted Lampholders
