Dangerous fitting or dangerous bulbs?

[Calvados]

We have 2 identical light fittings in our bedroom. Each fitting carries 3 x G9 Halogen. Last week my wife switched on the lights and one of the bulbs exploded. Only a small bulb but she said there was a blue flash, a loud bang and glass was absolutely everywhere, covering the floor and bed. It tripped the appropriate switch. I was away so did not see it happen.

I did not replace the bulb.

This morning the same thing happened to me. I switched on the bedroom light and one of the two remaining bulbs on that fitting exploded with a bang and flash. Our bedroom is pretty large but a piece of glass nearly hit me and I was stood by the door.

[FONT=Verdana, sans-serif]Does this sound like really dangerous bulbs or a broken fitting (or something else?)

To give you a bit more background. At least one of the bulbs in that fitting were less than 3 months old (G9 ES 42w = 60w equivalent).

The fittings themselves are approx 5 years old.[/FONT]

Grateful for comments/help

 

[bernardgreen]

Capsule bulbs such as the G9 are hazardous when they blow and should be contained in an outer glass envelope that will ( should ) contain the debris from an exploding capsule.

When the filament snaps some of it vapourises and this creates a plasma discharge inside the capsule. The current can be very high. Tripping the MCB instantly meant that the current was more than 6 amps. 6 Amps through the plasma means that 1.5 kWatts of heat was created inside the capsule (*). The metal and some of the glass vapourise and the pressure created shatters the capsule.

(*) to instantly trip a 6 amp MCB the current would be more than 10 amps and thus the power in the plasma could be more than 2.5 kWatts

 

[John D v2.0]

Agreed with above but only comment is B6 would need min 18A for a quick trip. Might even need 30A. The actual current could be far higher depending on the length of cable etc.

 

[winston1]

Replace them with G9 LEDs

 

[ban-all-sheds]

...G9 ES ...

Can't be both...

 

[Calvados]

Thanks all.

In layman's terms, if I reduce the wattage down from 42w (to say 30w) would that help?
I think I've had that wattage of bulb in the fittings since I bought them (although the 'new replacements' seem to be the ones that have blown which is why I thought they might be the cause).

I suspect I will have to pry what's left of the bulb out of the fitting. Will it be OK just to isolate the lights with the trip while I work on it or do I need to get an electrician to remove the fitting and take a look?

thanks,

 

[stillp]

Capsule bulbs such as the G9 are hazardous when they blow and should be contained in an outer glass envelope that will ( should ) contain the debris from an exploding capsule.

Bernard is correct.

if I reduce the wattage down from 42w (to say 30w) would that help?

The wattage will make no difference.

When you fitted the latest bulbs, were you careful to not touch the envelope with your fingers? Fingerprints on the capsule can cause it to shatter as it heats up.

 

[Calvados]

So the bulb wattage is fine...
I was aware about not touching but may have by mistake (although they were replaced over 2 months ago)...

Any help on how to remove the metal presumably still stuck on the fittings?

And I'm still not sure anyone has suggested what the issue may be?

 

[ban-all-sheds]

And I'm still not sure anyone has suggested what the issue may be?

Well...

the 'new replacements' seem to be the ones that have blown

Were they a known, reputable make?

 

[ericmark]

I had just not thought about it until your post, but I know with the 300W site quartz lamps if the glass got smashed they were taken out of service because of three independent problems, one was fire, second was sharps, and the third was they give out UV light and so either needed a glass cover which filtered out the UV light or had to be quite a distance from any personal.

With the MR16 lamp the quartz is contained within a glass envelope, but I have not seen any protection with G9 lamps, I have avoided the fittings using the G9 lamps as at the time I thought they were extra low voltage, in error it seems, but as a result avoided them as with extra low voltage using LED replacements is often a problem.

Since they are low voltage not extra low voltage the example I looked at rated 85-240 volt AC that would seem the simple way to make them safe.

The effects of halogen lamps extend beyond the laboratory. In addition to the subtle molecular changes, they are also capable of inducing erythema in humans. At a distance of 10 cm, a 100 Watt quartz halogen bulb can elicit erythema in just fifteen minutes. Over the course of a lifetime, this represents a 3.4-fold increase in the risk of developing a cutaneous malignancy [26]. In the lupus population, where patients are already hypersensitive to the toxic effects of light, it is likely that an even more pronounced reaction would be observed.

Luckily, the genotoxic, clastogenic, and carcinogenic effects of halogen lamps can be prevented entirely if the bulb is shielded with a silica glass cover [20, 21, 25, 27]. This discovery prompted the scientific community to demand compulsory shielding of all manufactured halogen bulbs [25]. Now, most halogen bulbs are covered with glass or “doped” with a special coating that filters out UV. However, these treated bulbs still emit UVA2, UVB, and UVC, though significantly less than the unshielded bulb [28]. Not surprisingly, the doped lamps are still mildly genotoxic to bacteria and can induce some chromosomal abnormalities [22, 27]. Thus they are not as protective as a silica glass covering, which seems to absorb all UV, but they are safer than an unshielded bulb.

Sorry could not find the British one.

 

[Calvados]

Were they a known, reputable make?[/QUOTE]​

From Amazon, cheap but with good reviews - not sure I can post the link if it is for negative reasons..

 

[ban-all-sheds]

And I'm still not sure anyone has suggested what the issue may be?

OK.

Here is my suggestion.

The issue is that you bought cheap bulbs from Amazon.

 

[ericmark]

I can see if you buy from a store like Screwfix there is a reasonable chance that their buyers have some knowledge about the product they are offering for sale, but in the main we buy bulbs at the same time as doing other shopping, so Asda, Tesco, Lidi, or Aldi and I would not expect these stores to have buyer who really know what they are offering for sale, if they did we would have never seen those lumps of plastic for sale which people are told if they put them in their sockets to defeat the built in shutters it will make them safer! in spite of not being marked BS1363 so clearly did not comply with British standards.

The fitting clearly should have a glass over the quartz bulb, it is not only the bulb which is faulty, these

adaptors I assume we are talking about? On sale at Edwardes whole sale and Ryness both UK firms, there should be a glass bit that goes over the quartz

for bits to go everywhere clearly that bit is missing?

Can't be both...

Ban did pick up on G9 ES but he did not seem to consider it was an adaptor.

 

[Calvados]

Re: the fitting - the bulb fits in the shade. It is not totally enclosed so when the bulbs 'blew' tiny pieces blew out of the top of the shade.
As someone said, they almost vapourised. This is the fitting

 

[ericmark]

To blow out of the top the cover shown here

must be missing.