Currently upgrading my lighting controls. Installed a Lutron Caseta Switch that is rated for 5A CFL/LED. Currently on that circuit there are 8 "LFT Shop Lights" with 2 bulbs each 4 footers. I don't have the rating of the ballasts or if they are electronic or magnetic switched. But the Switch gets VERY HOT and i'm assuming this isn't a wiring issue but more likely too much load on that switch. SO, was thinking of switching the bulbs to LED (if the ballast is compatible) to reduce the load. But was wondering if this will actually reduce the load. Meaning it's possible currently each bulb is pulling 0.5 Amps x 16=8 Amps overloading the switch. But will the ballast draw LESS current using the LED bulbs (assuming the lumens are similar and ballast is compatible)?

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    Use an LED that does not require keeping the old ballast. The ballast just wastes electricity, in this usage, due to hysteresis heating loss. It requires removing and replacing the fixture, but it will be much easier putting it back, since it will weigh far less. Aug 20, 2023 at 3:22

3 Answers 3


You seem to be throwing around 3 very different things:

  • Traditional fluorescent tubes, commonly used as shop lights. Typically 4 feet but sometimes 2 feet or 8 feet or other sizes. These typically have ballasts and starters.
  • CFL - Compact fluorescent lights. These are typically in an Edison bulb form factor (i.e., screw in replacement for incandescent bulbs). They are normally not long tubes - the whole idea is that they are compact. They have integrated ballasts in the base of each bulb and a twisty tube, though often that tube is enclosed in a frosted outer bulb so that you don't see the tube.
  • LEDs - available in many different form factors, including tubes (designed to replace traditional fluorescent tubes), Edison base bulbs (designed to replace traditional incandescent bulbs) and integrated fixtures - where there is no replaceable bulb at all but rather a case with a circuit board (driver) and a bunch of LEDs bonded to the case.

I suspect you have traditional fluorescent bulbs (long tubes with separate ballasts) connected to a switch that is not rated for that type of fixture/bulb. A typical old-style configuration for fluorescent bulbs is 40W per 4 foot bulb. If you have that, 40W x 8 fixtures x 2 bulbs = 640W. A more recent variant is typically 32W per bulb, which would be 512W. Both of those are close to 5A (600W) and yes, the type of ballast may affect things as well.

If that's what you have, I recommend replacing the fixtures rather than just the bulbs. If you replace the bulbs then yes, you will get some power savings. I looked up one example Philips from Home Depot and it is rated at 16W, compared to the typical 32W - 40W bulb that it replaces. However, you have to watch out for issues with wiring and ballasts - it is not nearly as simple/guaranteed as replacing an Edison base bulb.

Replacing the entire fixture is more work and more cost. But you do get more choice as far as dimensions/form factor and the actual electrical installation is extremely simple - hot, neutral, ground from the old junction box to the new fixture. No confusion as far as how (or if) to rewire the ballast, single-ended vs. double-ended tubes, etc. But look for a long warranty - 5 years is typical for integrated LED fixtures, even from the "junk" companies and other indications of quality. I have not had great luck with Commercial Electric (a Home Depot low-end house brand, essentially - I won't buy their lighting any more), but Home Depot has been great with warranty returns and done much better with some more established brands.

  • correct. I edited my OP. They are 4 footers. I don't have a thermal gun but that electronic switch gets very hot to the touch. The metal radiating fins are at least 100+ degrees maybe 110... Aug 20, 2023 at 14:00
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    If the fixtures are hanging from the ceiling on chains or installed in a similar fashion, replacing them completely is the best, cheapest, easiest approach. If they are installed in the ceiling, as part of the construction, you can buy LED replacement bulbs that don't use the ballast. You have to do a little rewiring of the fixture. Before buying LED replacement bulbs open up one fixture to make sure the ballast can be bypassed. On rare occasions it's molded into a plastic casing with the tombstone at one end. Then buy LED replacement tubes "for ballast bypass".
    – jay613
    Aug 20, 2023 at 14:56

The ballast is often removed from the circuit entirely when switching to LED tubes. Check the installation instructions. Personally, as a homeowner, I found it easier to swap out the whole fixture.


If you have the ancient F40T12 type fixtures with magnetic ballasts (audible hum; hard starting sometimes, observable flicker if you track your eyes across the ceiling) then your fluorescent fixtures are drawing 85-100W each or about 0.75-0.85 amps each. Eight of them would be 6-7 amps.

If you have the more modern F32T8 type fixtures with electronic ballasts, expect 60-70 watts each or 0.5-0.6A each, and eight of them would be 4-5 amps.

LED fixtures would use typically 45W per fixture or about 0.4 amps. Or 3-4 amps for all eight.

In all cases above I would expect the dimmer to get perceptibly hot.

So yes if your fluorescents hum a tune, turn off 3 of them to be in dimmer limits.

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