Excessive blowing of light bulbs

[John]

Right, about 14 months ago work was completed on a mid-terraced house that we inherited. It was completely refurbished with a view to letting it out, and part of the refurbishment was a complete rewire of the property.

The rewire was done by the builder (who is not a qualified electrician) but Part P was adhered to and, on completion, the relevant Part P police from the local BCO spent about five or six hours doing the full testing and inspection and were happy to give it a full and clean bill of health.

The tenant we have in there rang me today (I was out so I'm working on a garbled answering machine message here) to say that she's having a bit of a problem with the wall lights in the back room - they keep blowing the bulbs, which in turn trips the "fuse" (actually a 6A Type B MCB).

Each fitting has two arms and takes a 60W candle lamp in each arm. She didn't say if it was just one fitting or both that were the problem but she did say that in the 5 months she has been in the house, she has replaced *6* lamps in the back room but not a single lamp in any other room of the house has needed replacing.

Now, I know from previous postings in this group that it's not unusual, and it's not anything to be particularly worried about, for an MCB to trip out when a bulb blows - but what could be causing excessive blowing of bulbs in the back room wall lights?

Cheers,

John

[meow2222]

Damaged surface on the top of the bulbholder pins can do it. But in most of thsese cases it turns out the user's expectations just dont match reality. Only half of all lightbulbs make it to 1000 hours.

Today we use many more bulbs than was the case in the 70s, when 1 per room was very common.. Hence far more bulb failures.

NT

[Andrew Mawson]

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Assuming voltage spikes (from adjacent large motors etc) have been ruled out, as well as Euro 220v bulbs then the most common cause of early life failure in filament bulbs is excessive vibration. Particularly common in centre light fittings with kids bouncing arround upstairs (I kown this is a wall light). You could suggest the green option to her - they are far more tolerant of movement.

AWEM

[Colin Wilson]

If they're candle lamps, from what I remember they're more prone to early failure than a standard lamp (possibly temperature related ?)

[Owain]

If all the bulbs were bought at the same time, from the same batch, and have all had the same amount of use, they will all blow at around the same time.

It will take several cycles of replacement before the time needed before replacing a bulb becomes 'random'.

Owain

[The Natural Philosopher]

Crap 60W candle bulbs. I find most candles have appallingly short lifetimes and pop at the the slightest provocation and ALWAYS trip the MCB.

Best thing is to bulk buy a decent brand.

[The Natural Philosopher]

And all bulbs are not created equal.

When I did my kitchen and general areas with LV downlighters, the kitchen got 2 strips of 3 lamps.

ALL of these blew before the FIRST lamp from a different set blew.

[John]

"Colin Wilson" wrote in message news: [e-mail]...

Thanks NT, Andrew and Colin for your suggestions so far. I think I should have perhaps said that there are two wall light fittings in each of two rooms. Then there is a 5-arm centre light fitting in each of those two rooms, another 5-arm fitting in the hallway and another 5-arm fitting on the landing - all of which are the same matching design, from the same manufacturer and all bought on the same day from Homebase.

That makes a grand total of 28, 60W Candle lamps in the house but, as I said in my original post, she is only having to replace the lamps in the back room wall light fittings. *None* of the other candle lamps in any of the other fittings have had to be replaced at all - in fact, none in the entire rest of the house (a couple of 6ft twin flourescents (huge bathroom and kitchen with 12ft ceilings) and a couple of 100W Pearl) have had to be replaced yet.

Cheers guys,

John.

[Bob Eager]

Are there any dimmers on these lights? I had a situation where one bulb in a room started blowing frequently, just after I fitted an 'economy' dimmer. As soon as I fitted a normal switch, the bulbs stopped blowing. I later fitted an MK dimmer and all was well too.

Just an idea.

[meow2222]

christ

But we dont have the data to know why. Is it because she leaves those

2 on all the time? Is it a bad set of bulbs? Are the bulbs in reality lasting 100hrs average? Who knows. We really cant tell you whats going on because we dont have the data. And the tenant cant realistically expect you to tell her either.

Candles are on the whole rather fragile, because 25w filaments are so thin. But this doesnt apply to 60w.

The short response is 95% likely that its her problem. She of course will think otherwise, and will declare all landlords to be scumbags.

NT

[The Natural Philosopher]

Statistical blip.

Maybe she uses those more than any others. Maybe they are over a radiator. Maybe its sheer coincidence. Maybe its simply a bad batch of bulbs in those two lamps only.

[Owain]

That's what I said aloud, but I used the forename!

That's 300 watts of lighting in the hall and another 300 watts on the landing. It's installations like that that make me support mandatory low energy bulbs, even though according to one of the newspapers today we're all going to be poisoned by the mercury in them when they get landfilled because there is no proper disposal for them.

5-arm fittings are a bit awkward because it's difficult to run them on split load without them looking uneven. 6-arms can be wired to light up 2-3-4-6 lights and still look balanced:

00 *0 **

• * 0 * 0 0 00 *0 **

Using a combination of Marvel switches from Lundberg.

I'd not think highly of a landlord who landed me with the electricity bill for that sort of lighting.

Owain

[meow2222]

Well, yes, thats a done deal though. And who knows it might be high end rental.

NT

[Colin Wilson]

You'd love my kitchen - it's only about 3 foot wide (plus units both sides), but about 16 foot long. 550W of halogen light is almost enough to let you find stuff in the cupboards with your eyes still shut :-p

[Andy McKenzie]

For a different - non expert - view. I had a double spot light fitting (small incadesent lights) that used to blow bulbs regularly. When a new kitchen was fitted we had to bring earthing up to scratch and that light fitting (and it's switch) was removed and then refitted Since then it's bulb blowing behaviour has become 'normal'. It seems unlikely that the adding of an earth was the issue (or rather the connection of an earth that was already there to the light fitting) so I have always assumed that in refitting the unit I eliminated some vibration, or maybe a slightly dodgy connection. I would have thought it worth checking the mounting of the light fitting and the integrity of the wiring.

Andy

[John Rumm]

I have had exactly this same situation happen in the past in a neighbours house. She used to ask me to change the bulb for her (high ceilings). After I have done about one a month for several months (on a light that was not used that much), I replaced the switch. That fixed it.

(We had a massive discussion about this some years back, (with a bit of stirring from a US version of Dr. Dribble IIRC)):

[John]

No, there are no dimmers anywhere in the house Bob, but thanks anyway.

John

[John]

Owain, I know your replies in this group are normally helpful but lets not dwell on the environmental or cost of leccy bill aspect please as it'll help no-one. First of all, the tenant can choose to populate all lampholders or not; she can also choose to do it with 60W or 25W lamps, candle or otherwise, I really don't care.

This is a Victorian mid-terraced house with 12ft high ceilings and a dark hallway/landing even though the walls are a light beige colour. The light fittings we chose are both appropriate and functional for the property, and are well suited to the character and decor of the property - none of which matter in the context of my question.

I am merely looking for possible reasons as to why the wall light fittings in the back room should blow bulbs so frequently. As I stated, the builder is not a qualified electrician but is a good and concientious worker. He seemed to know - and follow - all the rules and regulations and we got the Part P police from the local BCO to inspect at first fix and then they spent five or six hours doing the final testing and inspection before declaring a perfectly good rewire, so I'm looking for ideas as to what could be wrong or what I should be testing for.

John

[John]

John, I reckon that I'll change the switch and see if that improves the situation. It's got to be worth a try for the cost of a 2-gang switch, to keep the tenant happy.

Cheers,

John

[Owain]

Not that high end if it's got candle-bulb lights from Homebase.

(No offence to OP, I'm sure it's all done in the best possible taste)

Owain