Low voltage transformers keeps blowing!

[neds]

I got a few ceiling spotlights using some of these transformers:

http://oceanlighting.co.uk/view-product.php?ProdID=00000000000365

Opened a failed one and looks like its proper blown, all black and smells. Not sure why its done it. I've had a few go on me now and its not normal surely?

Anything obvious that could be wrong?

Also I am replacing them with these:
http://www.screwfix.com/prods/48058...-Voltage-Electronic-Transformer-20-60VA-240V#

However these have a 1.0KV surge protection to the original 1.5, would it make much of a difference?

Cheers

 

[ColJack]

what kind of load are you running on these?
are you trying to dim them?
are they covered with insulation?

 

[neds]

Yes they are dimmable, and are insulated well, well as well as you can in that compact space. I have put the regulation 20cm of length so not sure if its a heat issue. Not sure on load? but running about 6 spotlights connected to the one dimmable switch.

 

[securespark]

Yes they are ......insulated well

Insulated as in covered in insulation?

If so, that's why they are frying...

 

[neds]

heheh i thought you meant no bare wires... its all got the sleeving?
Also whats wrong with the insulation tape to tie two sets of cable together, not the copper but the outer sheaths? Is it bad practice?

 

[Steve]

Just answer these questions. You have transformers that can supply 20 to 60 watts at 12 volts. What wattage of lamps are you using, and how many per transformer? What is your supply voltage (exactly, measured with a multimeter)?

 

[Adam_151]

WHats wrong with it is that it leasves a sticky residue when removed! but that wasn't Simon's point... he was meaning thermal insulation, that yellow rockwool stuff (normally) that would cause the power uspply to overheat if it was buried in it!

 

[neds]

OK cheers chaps very helpful.

Right to answer the questions:

- 20W bulbs
- One transformer per bulb
- Not sure on exact output will get the old multimeter out and get the figures later.

Also no thermal insulation where these transformers are!

 

[RF Lighting]

Unfortunatly a short lifespan is a side effect of installing cheap and nasty transformers.


I've never had a transformer fail on a 6" pendant set

 

[Taylortwocities]

 

[neds]

Hmm well I hope its as simple as that! by the sounds of it I don't think those screwfix jobbies are up to much kop either?