Low voltage light problem.

[IJWS15]

Daughter has a low voltage light on which a bulb blew and tripped the breaker (has blown several since September when it was installed but the previous ones did not trip the breaker).

She eventually (so she says) got it to stop tripping the breaker by pushing a bulb in and out lots of times. (Don't look at me I was near Antibes so could not help).

Went over to take a look tonight and the light does not work at all. Took the light down and transformer out. It is an Eaglerise SET105CV. See http://www.us2sunrise.com/english/english/product/lighting/euro4.htm

Some black marking aparant at the connection to the transformer and when the transformer was disconnected it has blown a component - took it apart and it looks like what used to be a fuse has blown in a big way scorching the board andblowing some carbon out through the gapo in the casing so it showed ont he outside.

Have checked the light with my (cheap) tester and with all bulbs out I get a "flicker" of continuity between live and neutral on the low voltage side - the needle moves about 5% of range - full circuit is 100%. Live to case is open circuit - not a flicker of movement.

She is looking for the receipt but may not have it (<12 months old) and has two of these lights (from Argos). Would I be right in guessing that there is something amiss with the lv wiring in the light itself (the above flicker when testing for continuity) or are these transformers notoriously unreliable?

If she cannot find the receipt where would I get an equivalent transformer, or as the loft is above could I put a more conventional transformer in the loft and run the 12 v down through the ceiling?

 

[breezer]

dont trust your meter for continuity on an electtronic transformer which is what it sound like you have.

yes you can get a new transformer, usual places sell them

 

[IJWS15]

I was not testing the transformer - it is definitely dead. I was checking the wiring in the light itself (transformer disconnected) in case there was a fault there that had killed the transformer.

TLC don't seem to have these and google brings up importers who will ship me a MOQ of 500!

 

[breezer]

TLC do have electronic transfomers, i have had quite a few from them. but TBH i would bin the light, now i know it was the continuity of the fitting it sounds like a bad joint / connection.

probably better to get a decent light unless shecan find the recipt. didnt have leds too did it? there was a post about an argos light with leds and lamps, they dont supply it any more as it was .............

 

[Space cat]

Would I be right in guessing that there is something amiss with the lv wiring in the light itself (the above flicker when testing for continuity) or are these transformers notoriously unreliable?

With all bulbs out and the 'transformer' disconnected there should be no meter movement at all. You have a leak - and the flickering movement suggests an intermittent short! If you don't track this down you will be tripping breakers and blowing transformers for many years to come.

She eventually (so she says) got it to stop tripping the breaker by pushing a bulb in and out lots of times.

There's a big clue there. Have a close look around that bulb holder.

 

[IJWS15]

Well, she found the receipt and they are just out of warranty.

Took the light apart this evening to try to find the problem and the only way I can replicate the continuity flicker is with my hand touching the light so I guess that my hand is providing the slight continuity path (9v tester).

The transformer fuse may be the cause of the problems, in blowing it spread metal/molten glass around the transformer.

Untitled

• IJWS15
• 21 May 2008
• 3

Anyone any ideas where I can get a similar round transformer??

 

[IJWS15]

I believe this will do the job and may even fit in the light case - any comments?

http://www.allaboutelectrics.co.uk/doc/12/vid/376/OSRAM_105VA_LV_TRANSFORMER.html

 

[RF Lighting]

How many, and what type lamps does the fitting take?

If its less than 105VA then that tranny should be fine

 

[IJWS15]

10 x 10w and she has 2 of the lights in the room plus a matching floor light.

An afterthought, I wonder if she has put a 20w bulb in . . Will check the bulbs tonight.

 

[IJWS15]

Fitted new transformer yesterday (105VA from TLC). Same rating as the one that came out and just fits in the case (Lengthwise).

Was fine when I turned it on but yesterday evening she was complaining about flickering. . . . . .

Other than a loose connection what could be wrong - going down to have a look later today.

10x10W bulbs fitted.

p.s. checked wiring insulation when I changed the transformer and no live-neutral flicker unless I touched the case (Path across my skin!)

 

[Space cat]

Perhaps it's overheating. Electronic devices can do strange things if they get too hot. Alternatively, a connection that measures OK when cold might be going bad when it gets hot. If the flickering only starts after it's been switched on for a while, that would be a clue.

 

[IJWS15]

I watched it for a while yesterday and no flicker at all. No loose connections.

Will see how it goes. It is mounted in the ventilated case that the old transformer came out of.

 

[IJWS15]

I behaves when I am there, she says it lickers occasionally when it has been on for a while and sometimes dims for a few seconds.

Will move the transformer out of the case and into the loft at the weekend. Will 1.5mm cable/flex be adequate for the current output from the transformer?

 

[Space cat]

Will 1.5mm cable/flex be adequate for the current output from the transformer?

It will carry the current (about 8 amps) but you should consider the voltage drop which will be about 200 mV per metre. How far away is the loft?

 

[IJWS15]

The loft is the thickness of a piece of plasterboard away.

Moved the transormer last night, now taped to a truss about two feet away from the ceiling light itself - no more flickering (Yet).