Saturday, 6 March 2021

MV bulb supply

Hi everyone.  I wonder if I might compare notes with anyone else who uses an MV trap regarding the supply of bulbs, especially 3-pin ones (as opposed to screw fittings).

There has been a lot of gloomy forecasting about the future availability of these and the main entomological suppliers do seem to be running short or indeed out.

I thought I had come to the end of the road last year, and again last week when my bulb finally expired after very long service. I've since rediscovered one which I ordered last year from an online supplier which I'll start using soon, I hope.  It is a lower wattage than my previous ones, 80W against 125W, but I am hoping that this doesn't make a difference.  I've just ordered another two from them and, unlike the entomological specialists, they and other online lamp firms seem to have good stocks. The pic below shows the packaging of the new one (left) and old ones.

I'm happy to shift to actinic eventually but I'm so used to MV and the choke etc, that I'd like to carry on for now.  I also have a couple of long-ago mis-ordered screw MV bulbs and if any of the many very handy people on this blog have simple advice about adapting my (Robinson) trap so that I can use them, I would be very obliged.  It may be a simple matter of finding the right socket at our local ironmongers but I am scared of electricity, so tips welcome. Again, the main entomological people don't seem to have advice or the right bits to help.

Finally, I am not sure how to dispose of old MV bulbs safely (hence the little exhibition of dud ones in my first pic).  I can ask next time we go to the dump but should anyone have the answer off pat, I'd again be very grateful.  Sorry about all these questions. All warm wishes  Martin Wainwright, Thrupp, Oxon


  1. Hi Martin,

    Firstly, Anglian Lepidopterist Supplies at offer an adaptor for three-pin to screw-thread (product code SK2013). I haven't searched for a year or so and things may have changed now, but when I last looked the screw-thread (ES27) 125wt bulbs were still to be found fairly readily on the internet even though the three-pin versions may have disappeared.

    I'm afraid I know very little about electrics either but you really need to speak to someone who knows before trying to run an 80wt bulb off a 125wt choke - I'm not sure if that would work safely! I've also found through personal experience that Venture 125wt bulbs seem to have a much higher failure rate than other brands so that's something to keep in mind too (not that there's much choice of manufacturer these days).

    The twin-30wt actinic Robinson is what I use the most at home and it gives really good results. When/if you do head towards an actinic system, ALS also offer a conversion for the Robinson so you wouldn't need to buy a whole new trap. The conversion includes the electrics and choke (you'll still need a choke if running off the mains) as well as the cone/vanes/bulbs that should fit your trap. Your Robinson looks like an old Watkins & Doncaster trap so you'd need to check that the diameter of the hole in your perspex is compatible with the conversion kit, but you'd need to speak to Jon Clifton at ALS anyway so he would be able to confirm.

    Like batteries, etc, old bulbs should be taken to your local recycling centre for disposal. The important thing is not to put them in your waste bin!



  2. I run an 80W MV and when I bought the choke it was sold as an 80W. However, last year I had occasion to open the case and noticed it was in fact a 125W. Which means I have been running that set up for the last 5-6 years. There was some discussion on the point on the "Moth Traps UK" facebook group; someone commented that some chokes have both 80W and 125W ports. Mine does have two ports but there is nothing to indicate that it is anything other than 125W. It is very similar to this - - which states that it will run between 80-125W.



  3. Thanks so much both. That's really helpful. We've got an excellent electrician coming shortly to do other things, so I'll see what he says about the wattage. I'll order the SK2013 converter too - v many thanks and all warmest, M

  4. Hello, Martin. As a non-user of MV bulbs, I can only offer one tip. I believe that the only purpose of the third pin was to prevent its use in normal light fittings that have no choke: the third pin has no electrical purpose. So when you run out of three-pin bulbs, one option is to change your socket to a standard screw version: no need to change the choke (if the bulb has the same power rating).

  5. Hi Tim and thanks so much - belatedly, sorry. That's a very useful thing to know and I'm much obliged. I think I'm going to be lighting up the night sky for a while yet thanks to all this help. All v best M


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