We always run out of the fuse bulbs, and there are so many different light-sets that it is difficult to get replacement fuse bulbs.
It seems to me that it would be much simpler if there were a fuse in the plug, with a specified amperage.
Is there anything one can do along these lines?
The problem isn't that bulb failure results in the set drawing a higher current, this stays the same, except the same amount of current is now distributed amongst fewer bulbs.
Sparks...
a) don't buy them at all
b) keep a complete spare set of lights and when the first set fails throw the whole thing away and use the replacement.
c) Buy a replacement set for the replacement on Christmas Eve for £3 and remind yourself of (a)
Unfortunately the fuses for 13A plugs are 3A and 13A, with other ratings for FCUs.
I don't think a fuse of the lower rating needed for Xmas tree lights would have the breaking capacity to be suitable for use as a plug fuse, and there would always be the risk that someone would substitute a 13A fuse.
A fuse-bulb is cheapest for the manufacturers, and when you consider the rock-bottom price of many of the sets, cheapness is what counts.
Fuse-bulbs shoulnd't be blowing that often - unless lots of ordinary bulbs have already blown, or you've replaced some bulbs with the wrong rating.
Owain
Check out wholesalers shortly after the holiday. They near give them away.
If its a modern set with shorting bulbs, and you dont use a fuse bulb, if 2 or 3 bulbs go then thers start going faster, and you get a chain reaction of bulbs blowing. As this happens, remaining bulbs get more and more power eacha nd start popping uberfast ,until theyre all shorted. Then the plug fuse goes. You're left with a 100% dead set, plus the risk of bulbs shattering and sort of explodng along the way. IOW use a fuse bulb.
If its an old set with non shorting bulbs, a fuse bulb is not particularly important, and those old sets can safely run without one. Every bulb acts as a fuse. But if you put modern shorting bulbs in, this changes.
NT
No idea where you got that notion from. You can use any BS1362 fuse which is ASTA certified in a 13A plug, which is all values I've come across except the 1A ones.
Trouble is, to replace the fuse lamp, you would need something more like a 0.1A fuse, and there isn't a BS1632 value that low.
The much more serious risk, and it happens a couple of times a year, is that the light set ignites the christmas tree. Anyone who has set light to a tree after christmas will know just how disasterous that would be in your living room (they don't so much burn, as explode).
All series sets I've seen to at least 50 years old have shorting bulbs.
Buy a set of low voltage (LED) lights
That's completely wrong. Failed bulbs go short circuit, so the total resistance in the series circuit falls and the current rises. The remaining bulbs are over-run and thus more likely to fail too. Eventually a chain reaction occurs and, without the fuse bulb, you'd end up with a short across the mains, possibly setting fire to the thin wire.
The fuse bulb, if present, should stop the chain reaction before it's got too far. I suppose a 2 A plug fuse would protect the wiring and prevent a fire, but not until you'd lost all the other bulbs. (1 A plug fuses are available, but aren't ASTA or BSI approved and shouldn't be used.)
The message from "Dave Plowman (News)" contains these words:
I bought two sets for 50p each a few years ago post-Christmas, and the sodding things refuse to die.
shouldn't be used.)
There are plenty of 1amp fuses that meet BS1362 and there is no reason not to use them.
For example -
It's not whether they comply with BS 1362 that matters, it's whether the particular fuse has an ASTA or BSI approval certificate to that standard. It used to be the case that the 1 A rated types (which aren't sand filled) weren't so approved.
However, having just looked at the data sheet for the Bussmann TDC180 I see it says that the 1 A version is approved, so I stand corrected. I'd still check that the fuse has the approval markings before using it though.
I wonder why the difference. I saw nothing but non-shorters till around
1990ish. PITA they were as well.NT
Andy, could you explain that to me in words of one syllable. Complying with a BS doesn't mean that it is BSI approved?
(This is a genuine request for information not a sarcastic comment)
Complying with a standard just means that the product meets all the (relevant) requirements of the standard. A manufacturer could be confident of this by design plus testing if necessary. This testing could be done by the manufacturer himself.
Without any reference to a third party, you've only got the manufacturer's word for it. They could be wrong, or even telling lies.
An approval certificate, OTOH, is evidence of third party examination and testing of the product by a approval body, themselves vetted. The approval process will also usually examine the manufacturer's ability to continue to produce compliant product (i.e. their QA system). The approval results in a licence to apply the approval mark of the approval body (a certification trade mark) to the product for a set period of time.
HTH
The message from snipped-for-privacy@care2.com contains these words:
Talking of pains in the arse, I had a two-way adpator fail today. Spectacularly. When I took it apart the live contact was melted and spattered all over the place. It blew the 13A fuse in the adaptor, the fuse on the 4-way block it was plugged into[1], tripped the ring MCB and the main breaker on the CU. Ooops.
[1] Yeah, yeah, I know.
The heat and consequent light of a bulb is generated by current. If the bulbs get brighter when one blows, then it must be because the current has increased. The voltage of the mains is distributed over fewer bulbs, so each gets a higher valtage. As the voltage increases, the current increases, and that increases the heat, but also increases the resistance, providing some negative feedback, but the current does still increase.
I suspect though, that the current increase is fairly small, and so the fuse bulbs need to be very sensitive.
-- JJ
Even I remember them from the 70s. They were screw-in, rather than push-fit, and took an age to diagnose which one had blown when you got them down from the loft. I don't know why, but a set would last all Christmas, with no problems, then they were packed away working. On getting then out again the following year, at least three bulbs would be blown.
-- JJ
Sorry Andy but I must be very thick 'cos I still don't understand.
What more can you ask than that a product meets all the requirements of the standard? If it walks like a duck etc then it is a duck.
But you just said that "Complying with a standard means that the product meets all the requirements of the standard". Did you mean to say that complying with the standard doesn't always mean that the product meets all the requirements of the standard?
So what is the point of the standard?
Just goes to show how fails-safe the system is with so many back-up protective devices :-)
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