More bulbs

I wrote the other day about new bulbs for my car and now I’m writing about bulbs for the spot lights in my kitchen.

We’ve got two 4-way halogen spots in the kitchen, each holder taking a 50W bulb. Now before all the eco-warriors out there decide to try and spam me to oblivion, here’s three things:

  1. they’re fully dimmable and rarely used at full power
  2. we do need that much light in the kitchen to make it workable
  3. it’s my ‘leccy bill anyhow

A bulb blew just before Christmas and I used our last remaining spare 240V 50W halogen bulb replacing it, so I went to the supermarket and bought a pack of 5 Osram ones. Thought I would go for the named brand as they might last a bit longer and advertised 30% more light for the same input power. I replaced the blown bulb and was immediately impressed with how bright it was.

I think it was partly because the light seemed much more blue than the others that I thought I would replace a second bulb to see if I had a dud. Nope – that one seemed to be the same – they must just be that much brighter. I left the kitchen, switching the light off, then came back 10 mins later and was clearing up something when the newly-replaced bulb blew. Ah! It must have been faulty all-along.

I duly replaced this bulb with a second one from the same pack. That one lasted an even shorter length of time.

Hmmm… something’s obviously not right here. Two bulbs failing within minutes of installation? Surely that’s not coincidence. I was looking at the failed bulbs carefully to see if I could see a common manufacturing defect which would cause a faulty batch to be produced. That would certainly explain it. That’s when I noticed the manufacturing print on the bulb itself. The bulb was rated at 120V, 50W. In other words, it would be drawing twice the current it should have been – that explains why it was very bright and why it lasted such a short amount of time. I needed to double-check it, but yes, I’d bought a box marked 240V (as expected in the UK), containing bulbs which were actually rated at 120V.

A couple of things struck me:

  • How the hell did the bulb not just go bang at first startup? As I said earlier, the lamps are dimmable which is acheived via an electronic dimmer control, which always “soft starts” the bulbs (i.e. fades them up). This reduces thermal shock suffered by the bulb which would normally go from room temperature to over 200C in milliseconds. This soft start might have helped it survive a few more minutes.
  • I was impressed by the fact that it ran at all and just expired like any other light bulb, rather than a ceiling-based firework.
  • I’m glad I hadn’t replaced all bulbs in the fixing at the same time. That would mean a huge increase in current through the wiring, which could have had disastrous consequences.

I wrote to Osram via their website and very quickly received the following reply:

Dear Ian, thank you for your e-mail.

This is certainly an issue that needs our urgent attention. By return, could you please let me have details of the location of the store from where the lamps were purchased, and also your own home address, so I can arrange to send you some replacement lamps? Thank you for bringing this matter to our attention.

After a couple of further e-mails confirming details, some replacement bulbs were dispatched to me with a small “with compliments” slip. Now I think that’s a bit tight of them – an extra 2 or 3 wouldn’t have gone amiss as way of apology for the inconvenience and for bringing it to their attention.

At least I can see properly in my kitchen again.