I have an old illuminated bathroom mirror which has ceased illuminating. Before it stopped working, it would sometimes take a while to illuminate after pulling the toggle switch; now the switch still 'clicks' when toggled but does not otherwise work.

The mirror innards:

photo of mirror innards


  1. wall plate for power cable
  2. plastic housing for terminal block, switch and what looks like a transformer (?)
  3. ballast device
  4. T8 fluorescent tubes (2x)

There's also a shaver plug on the side of the mounting -- black box lower left -- which isn't part of the lighting equation (I think!).

Detail for 2:

transformer, terminal block, switch

Left to right: transformer (?), terminal block, switch

Detail for 3:


Finally, the product sticker:

mirror product sticker

Searching for these product codes on B&Q's website yields no results.

I have tried testing for voltage with a non-contact tester (from 1 to 2) and the tester illuminates, so the supply seems to be good. I also checked the live and neutral wires leading to the ballast, which produce a result when the switch is operated, however the brown wires coming from the ballast do not cause the non-contact tester to light up. Finally, I have visually inspected for obvious defects (eg a wire that has wiggled free from a terminal block) but there's nothing that I can see which is clearly wrong to my eyes.

I haven't tried new tubes as I thought the chance of both failing at once was less likely, given other symptoms. I'm on quite a tight budget so I'd prefer to avoid the "troubleshoot by replacement" approach if possible!

Is there further troubleshooting I can do? I am wondering if the result with the non-contact voltage detector and the pre-failure symptoms suggest a faulty ballast. If so, is there a way I can definitively confirm this?

  • Suggestions for improvements to the Q are welcome, as always. I also welcome frame challenges, but if a repair is infeasible or impractical, I am planning to ask a follow-up Q about how I might modify this to run on LEDs :)
    – bertieb
    Commented May 24 at 9:58
  • 1
    You have tried new bulbs/tubes (didn't see that mentioned)?
    – Huesmann
    Commented May 24 at 11:34
  • 2
    In order, bulbs, ballast, wiring. (You might find it cost effective in material costs to switch to led right away… ballasts aren’t cheap.) Commented May 24 at 11:47
  • @Huesmann You're right to suggest that- I've not tried new tubes as I thought the chance of both failing at once was less likely, given other symptoms. I'm on quite a tight budget so I'd prefer to avoid the "troubleshoot by replacement" approach if possible, which I probably should have mentioned in the question...
    – bertieb
    Commented May 24 at 12:30
  • @AloysiusDefenestrate Agreed that switching to LED is probably the better option; thinking about it I might have been better to simply skip to the "how do I convert this fluorescent mirror light to LED" question right away, but I prefer to repair where possible :) (cf this Q from some years ago - which was another 'replacement is easier than repair' situation!)
    – bertieb
    Commented May 24 at 12:30

1 Answer 1


My experience with short fluorescent lamps was that they had limited lifetimes, and that their ballasts ran hot and also had limited lifetimes.

As you state, you'd be far better off switching to LED lighting. A quick search on Amazon showed some LED replacements for "18 inch", T8, 15 W fluorescent tubes. My choice would be one that does not use the original ballast, such as this example (which is for 120 VAC) or this from Keystone (rated 120-277 VAC), because that is more efficient, and also because the original ballast might be defective. It does require removing the old ballast, but your excellent photos show you'd have no trouble doing so. Note the color temperature, particularly important for a bathroom mirror. 3,000 K is warm white, and 6,000 K, at the other extreme, is actinic white.

  • This is precisely what I ended up doing, though I couldn't find a decent local supplier who would ell me fewer than half a dozen and would also tell me the price in advance
    – bertieb
    Commented Jun 3 at 14:42

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