Changing a fluorescent strip light for an energy saving one.

[Chardonnay2407]

Hi. I need to change the above light fitting but research says you have to remove the ballast otherwise the energy saving properties will be lost. How do I do this please? Thanks Jo

 

[securespark]

A fluorescent fitting is already an energy saving one.

How long is it?

Are you converting it to LED?

What are you saving in watts?

 

[ericmark]

It depends on the type of ballast used and when I looked into LED v fluorescent for a 5 foot fitting there was no real energy saving between LED and fluorescent when using a HF ballast. The LED tube was rated at 100 lumen per watt and the fluorescent tube with a wire wound ballast was rated at 90 lumen per watt, however there is a 10% gain in light output when using a HF ballast plus tubes should last 30% longer so in real terms both have the same life and energy use.

However finding a LED tube with the same output as a fluorescent tube seems to be hard. With my example a 65W fluorescent (5100 plus lumen no longer made so can only use data for a 58W tube) was replaced with a LED tube of 24W (2400 lumen) so it was not the increase is efficiency which saved money but the reduction in light output. i.e. the same as replacing a 100W bulb for a 40W bulb.

I looked at the rewire and there is a problem one end of the replacement was short circuit the other end was 230 volt input. So although one can wire 230 volt across one end if the tube is replaced wrong way around in the future that is a direct short, or if a fluorescent is fitted you get 230 volt across a 3 volt heater.

So both ends need to be wired in series so that fitting tube either way around will work. This could still cause problems if a fluorescent tube is fitted instead the ballast does two jobs, it gives a high strike voltage and also limits the current once fired up, so fitting a fluorescent tube in a rewired fitting without a ballast it is unlikely to work but if it did strike then it would take well over the design current so a sticker is required telling people not to fit fluorescent tubes. In case they do a replacement starter is included which it seems acts as a fuse. Again dangerous as if this starter is used with a fluorescent fitting it will put 230 volt across the two 3 volt heaters one assumes the starter will fail before the tube but never tried it. It is not a simple link or fuse inside and I have failed to find out what the component is so don't really know what would happen.

So with a wire wound ballast all you do is short out the ballast and renew the starter. With a HF ballast it becomes more complex as needs a full rewire. This is a problem as there is no starter socket with a HF ballast to fit the fuse into. There may be a fuse holder in the fitting but you are not provided with the fuse to fit it. I would fit a 1A fuse.

I wired mine in hind sight wrong. The line and neutral goes to the pins at one end only, so replacing the tube could cause problems. I did it that way simply because my wife had deposited rubbish (she calls it craft supplies) under the lamp and as a result I just could not reach all the wiring to be able to rewire it. Had I been able to buy a 65W tube I would not have changed it. To renew the ballast required the whole fitting to be removed from the ceiling to unbolt the ballast. Had that been an option then I would have swapped to a HF ballast which would have been far better. Only reason for using a LED tube was access problems.

To be frank the 2400 lumen is enough for that end of the kitchen it does not really need 5100 lumen. But although swapping a 100W bulb for a 40W bulb may save energy I would not call the 40W bulb an energy saving bulb. In the same way fitting a lower output tube may save energy but there would be no gain swapping fluorescent to LED if the LED has the same lumen output as fluorescent all it does is make cost of replacement jump from £3 to £17.09.

As to the saving by removing the ballast not sure if I was doing same job again I would bother. As the tube length increases so the voltage across the tube also increases and the impedance of the ballast reduces so very little saving with an 8 foot tube, quite a large saving with a 2 foot tube.