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Any Electricians Around - Need Help & Advice!

Suave

Distinguished Member
Hi All,

I have a number of low voltage ceiling lights in my ceiling arranged in 2 rows. These are connected to Dimmable LV Transformers & each row is connected to a 2 Gang 400W Touch Dimmer.

They were all installed by a professional electrician. I had a problem soon afterwards when some of the lights stooped working & further examination showed that some of the brand new transformers were not working & had to be replaced. A couple even showed very bad heat/melting damage which concerned me greatly.

I had them replaced by another electrician & all went fine for a while. Soon after, a number of lights now do not work & the from the ones that do, they randomly come on & off by themselves.

I want to sort this out properly now & not just rely on verbal assurances - I need to know once & for all taht the problem is sorted! Can anyone give that knows about electrics give me an idea as to why this might be happening so the next electrician I call in is made aware of what to look for?

The ceiling lights are Aurora AU-DLL552W with Low Voltage 50W bulbs each connected to a Dimmable LV 12V 20-60VA Transformer. On one row, there are 5 lights & on the other there are 7.

The Touch Dimmer is a Varilight Ultra-flat Screwless 2-Gang 400 Watt Dimmer. I have attached pics so you know exactly what I have & how it is set up! Would really appreciate help on this as fed up of the problem, want to avoid any safety issues & having to keep paying professional electricians over & over again!

Many Thanks,

Suave!

Square Adjustable Downlight White by Aurora

Aurora - Technical Datasheet

iDii402MS - Varilight - Flat Plate Screwless - Iridium Black - 2x 400W Touch & Remote Control Dimmer: Amazon.co.uk: Lighting

http://www.1stopelectrics.com/image/product/idii402ms/2/.pdf
 

Attachments

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  • Varilight Dimmer.jpg
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  • Aurora AU-DLL552W.jpg
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  • LV Transformer 12V 20-60VA.jpg
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niceguy235uk

Prominent Member
Get rid of the dimmers to start with and use normal switches.

That way you can rule them out.

The fittings and transformers should be completely clear of any insulation that is above the ceiling, regardless of whether the fittings are fire rated or not.

Finally, i have been fitting these things for years.

Lets just say the quality of the lamps and transformers is not getting any better.

Also, unless the dimmer specifically states, the rating should be halved for halogen lighting.

EG A dimmer rated at 400W should only have a load of 200W halogen.

Some Varilight dimmers dont need to be though.
 
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Suave

Distinguished Member
Get rid of the dimmers to start with and use normal switches.

That way you can rule them out.

The fittings and transformers should be completely clear of any insulation that is above the ceiling, regardless of whether the fittings are fire rated or not.

Finally, i have been fitting these things for years.

Lets just say the quality of the lamps and transformers is not getting any better.

Also, unless the dimmer specifically states, the rating should be halved for halogen lighting.

EG A dimmer rated at 400W should only have a load of 200W halogen.

Some Varilight dimmers dont need to be though.

Hi,

Thanks for replying! I will ask the next electrician to see if it a Dimmer problem but I really would like the option of a dimmer control as it would now be just too bright without one - I planned a lot of things around having dimmable lighting!

I have made sure that the fittings & transformers are clear of any insulation if that helps. As for the light unit, I thought I had bought a decent branded make in Aurora & not some el cheapo ones as I did not want to skimp on electrics - are these lights not any good then?

The same for the dimmer, it is from what I was told was a very decent brand & not exactly cheap for a dimmer (£50!!) & was told that I could put a 400 Watt load per gang so as I was running bulbs totalling 250W On one row & 350W on the other, there should be no problem? How do I know/can find out if my Varilight Dimmer needs to have it's rating halved or not?

Any idea what the problem is as to why the lights/transformers keep blowing & why the remaining working lights randomly come on & off by themselves?

Suave!
 

Sparky83

Established Member
Hi,

The below is a post i have seen in a thread on another forum, but the OP was basically asking if derating was required.......
Ok time to dispel some myths...

De-rating dimmers for use with halogen is no longer required. Assuming you use good quality lamps, and dimmers.

There is nothing special in normal operation about a halogen lamp. If it's 50w thats how much power it will use! Where de-rating came in was that when the a halogen lamp fails, it can draw a very high current for a short period.

However lamp and dimmer manufacturers have worked to address this and there probably no issues with running full load on a dimmer now.

Take a look at the MK website, they show that the dimmer can handle 200% overcurrent without damage.

(caveat - if you buy cheap dimmers, and 50p lamps then it may well go TU, also check you dimmer specs, if it says on there you should de-rate, then do as they suggest!)


But if your ones are cheap i guess its possible that they are causing the issues, if its not all the lights effected all the time it may not be anything to do with the dimmer, but as mentioned before me, best bet is to replace with a normal switch to see if it still happens. How much of a gap is there between the ceiling they are mounted in and the floor above? is it a normal gap? They may be over heating and this is causing the issues?

Personally i prefer GU10 mains voltage lights as no matter what trannys or lamps you get they always seem to die very quickly, at least with GU10's there is no tranny to die and cost to be replaced.
 

niceguy235uk

Prominent Member
As i said, there is no such thing as a good quality lamp or transformer, regardless of make.

MK dimmers may well be able to handle massive overcurrent, however, they recommend that only 5 transformers are connected.

And here, we are talking about Varilight.

Also, run a dimmer close to full rating, and you will have problems.

Technology is moving forward at a fast rate, but there are still precautions to take.

Finally, i would never any advice from any member of the Screwfix forum.
 
niceguy235uk said:
As i said, there is no such thing as a good quality lamp or transformer, regardless of make.

MK dimmers may well be able to handle massive overcurrent, however, they recommend that only 5 transformers are connected.

And here, we are talking about Varilight.

Also, run a dimmer close to full rating, and you will have problems.

Technology is moving forward at a fast rate, but there are still precautions to take.

Finally, i would never any advice from any member of the Screwfix forum.

Wow, what's the weather like up there on your high horse?
 

Berties

Banned
Never been impressed with halogens, from buzzing transformers to red hot (and these were in the open) I'd stick with LED tbh, or low energy bulbs. Ones that are powered straight off the mains without a "hot brick" transformer.
 

Suave

Distinguished Member
Hi All,

The bulbs I am using are genuine Aurora MR16 Square ones & they are not cheap or easy to find! I really know nothing about these things but went Low Voltage as that was advised to me at the time as much better, greener & much cheaper!

I presumed Varilight was a good make as the Dimmer cost £50 & was not a cheap discount store type! Also, it seems lots of reputable places sell the brand so I did not think I could go wrong with either Aurora & Varilight!!

I know I cannot change things now as it would probably be too much cost & hassle so I guess I am stuck with the set up I have - I just need to get it all working again in a safe & reliable manner but I would not know what is causes the lights/transformers to keep failing on some lights & make the remaining ones act like they have their own will!!

Suave!
 

Sparky83

Established Member
niceguy235uk said:
As i said, there is no such thing as a good quality lamp or transformer, regardless of make.

MK dimmers may well be able to handle massive overcurrent, however, they recommend that only 5 transformers are connected.

And here, we are talking about Varilight.

Also, run a dimmer close to full rating, and you will have problems.

Technology is moving forward at a fast rate, but there are still precautions to take.

Finally, i would never any advice from any member of the Screwfix forum.

That was the first of many threads in various different forums about not having to de rate ALL dimmers, and the theory behind it makes sense, how does the dimmer know wether it has a 50w lv or a 50w 230v halogen stuck on the end of it, 50w is 50w, yes there is a little extra to take into account for the tranny but still roughly the same.
 

niceguy235uk

Prominent Member
Hi All,

The bulbs I am using are genuine Aurora MR16 Square ones & they are not cheap or easy to find! I really know nothing about these things but went Low Voltage as that was advised to me at the time as much better, greener & much cheaper!

I presumed Varilight was a good make as the Dimmer cost £50 & was not a cheap discount store type! Also, it seems lots of reputable places sell the brand so I did not think I could go wrong with either Aurora & Varilight!!

I know I cannot change things now as it would probably be too much cost & hassle so I guess I am stuck with the set up I have - I just need to get it all working again in a safe & reliable manner but I would not know what is causes the lights/transformers to keep failing on some lights & make the remaining ones act like they have their own will!!

Suave!

You gotta start somewhere so change the dimmer to a switch.

If you have a multi meter, check the output of the transformer is around 12V.

If not, swap it out for a new one.

Unfortunately you are stuck with the lamps due to their shape.
 

Sparky83

Established Member
You gotta start somewhere so change the dimmer to a switch.

Totally agree here, easiest option and will show you either way that it is the dimmers or not.

And also taking some of the lamps out to see if that stops it, although this should be doenwith the dimmer still connected, if this works then as Niceguy said your dimmer isnt rated correctly.
 

maxwell

Distinguished Member
I hope you have good fire insurance !

Nothing to do with the dimmer switch as that is fitted on the primary side of the transformers - as each gang of the switch is 400w and you have 60va*5 = 300w on one and 60va*7 = 420w on the other assuming the maximum VA rating of each transformer is being used.

The problem is your transformers -

the transformers you are using are capable of outputting 11.5v with a maximum load of 4.9 amps (dont take this as gospel though as thing vary with components used etc)

so if we calculate it using the output voltage of the transformer :

each lamp will pull 50/11.5 = 4.34 amps on its own which is already close to the maximum rating of the transformer.
I have not used any power factor correction here as the lamps are nearly a full resistive load so are close to unity, if anyone does want to recalculate with pf correction you could use the value of 0.95 or 0.8 if you want

Running at close to maximum for sustained periods will generate heat and lots of it, also note that the use of the dimmers can increase this.

The above assumes that there is one lamp per transformer so you have a total of 12 lamps and 12 transformers if this is not the case you need to disconnect this circuitry immediately

I suggest you contact the 'electrician' that originally fitted this equipment and insist he fits uprated transformers whilst you still have a house to fit them in.
 
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cunny678

Distinguished Member
Just a suggestion, but could you live with lower watt bulbs - 35W etc?

I had a similar problem at home and as previous posted suggested the transformers couldnt handle bulbs at 50w but are OK at a lower wattage. I also found that the transformers and fittings were covered with loft insulation:eek:
 

Suave

Distinguished Member
I hope you have good fire insurance !

Nothing to do with the dimmer switch as that is fitted on the primary side of the transformers - as each gang of the switch is 400w and you have 60va*5 = 300w on one and 60va*7 = 420w on the other assuming the maximum VA rating of each transformer is being used.

The problem is your transformers -

the transformers you are using are capable of outputting 11.5v with a maximum load of 4.9 amps (dont take this as gospel though as thing vary with components used etc)

so if we calculate it using the output voltage of the transformer :

each lamp will pull 50/11.5 = 4.34 amps on its own which is already close to the maximum rating of the transformer.
I have not used any power factor correction here as the lamps are nearly a full resistive load so are close to unity, if anyone does want to recalculate with pf correction you could use the value of 0.95 or 0.8 if you want

Running at close to maximum for sustained periods will generate heat and lots of it, also note that the use of the dimmers can increase this.

The above assumes that there is one lamp per transformer so you have a total of 12 lamps and 12 transformers if this is not the case you need to disconnect this circuitry immediately

I suggest you contact the 'electrician' that originally fitted this equipment and insist he fits uprated transformers whilst you still have a house to fit them in.


Hi Maxwell,

Many thanks indeed for your kind help. I am very upset to learn this is a serious fire risk as I went via professional electricians & used transformers either as supplied and /or recommended suitable for the lights. Your points seem to be entirely relevant to me as that would explain why some transformers were heat damaged & showed signs of melting I guess?

Each light does indeed have it's own transformer but they are all the same rating. Please can you very kindly recommend me some safe, suitable & reliable transformers that I should now get & replace the existing ones with? It seems I just cannot rely on what tradesmen tell me who come round anymore so need to get reassurance from pro's like you.

Also would it make any better, safer or more sense to use lower wattage bulbs - say 35watts each instead of 50watts each?

In the meantime, what can I do to temporarily make things safe & eliminate any fire risk?

Thanks so much,

Suave!
 
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niceguy235uk

Prominent Member

Stop scaremongering ***.

Are you suggesting that we all now install 105va transformers for each 50W lamp used? No.


The transformers rating at 60va is perfectly fine as this is exactly what they were designed for, its the dimmers that are the issue and or a connection somewhere.

The reason they were damaged could be anything at all, insulation, insufficient ventilation etc.

I have even been called out and found transformers leaning up against a bare lamp.

The lamps run at over 200C. Thats where most of the heat is coming from, not the transformer.
 
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Well done, nice comeback. :hiya:

Why does every bit of advice (which is always correct I may add) you give have to be wrapped in a rude, up ones own arse way?

OP, think about LED's, plenty of good ones out there and they produce little heat, draw less power and give a lovely light. They are very expensive however.

Edit:- Although Niceguy will disagree as he's never seen a decent one apparently :)

Much better than it is down there.
 

IronGiant

Moderator
I think he gets a bit frustrated at the crap advice given out by arm chair experts who rely on the screwfix catalogue to recommend things :)

And I'm as guilty as the next man of that :blush: :thumbsup:


being an arm chair expert with a screwfix catalogue that is...
 
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maxwell

Distinguished Member
I think he gets a bit frustrated at the crap advice given out by arm chair experts who rely on the screwfix catalogue to recommend things :)

And I'm as guilty as the next man of that :blush: :thumbsup:


being an arm chair expert with a screwfix catalogue that is...

Well Im not an armchair expert with a screwfix catalogue, I have been an electrical engineer for the past 30 years and as for mr niceguy I suggest he reads a few more of the the B&Q leaflets before he gives any more good advice.
 

Suave

Distinguished Member
Hi,

How much of a gap is there between the ceiling they are mounted in and the floor above? is it a normal gap? They may be over heating and this is causing the issues?

Personally i prefer GU10 mains voltage lights as no matter what trannys or lamps you get they always seem to die very quickly, at least with GU10's there is no tranny to die and cost to be replaced.

The room is an upstairs bedroom with the loft above. Above the beams/joists in the loft, it is laid over with wooden boards to make storage easier so the lights & transformers are under these boards. Holes have been drilled into the boards above the lights to let the heat dissipate & all the insulation removed in each section where there are lights.

The lights are just as shown - I do not know if this is important or relevant but there is no metal casing or cover - they are just open/exposed - I was told these would be legal & OK since as there is a loft above, the lights do not have the "fire rating" casing?

I had 4 100w R80 lights with the large screw in bulbs but the electrician told me to go Low Voltage as it was much cheaper, safer & better than the old mains 240v system.

Never been impressed with halogens, from buzzing transformers to red hot (and these were in the open) I'd stick with LED tbh, or low energy bulbs. Ones that are powered straight off the mains without a "hot brick" transformer.

At the time I heeded the advice given & to be honest I was given the impression that Low Voltage/Halogen was Low Energy!!

You gotta start somewhere so change the dimmer to a switch.

If you have a multi meter, check the output of the transformer is around 12V.

If not, swap it out for a new one.

Unfortunately you are stuck with the lamps due to their shape.

Yes, at the time, I bought the lights based on their design & looks so I am indeed stuck with the square bulbs - I was given the impression that they last for years so thought it might not be such a big deal!

I will make sure the next guy I find will check out the dimmer & see if that is causing any issues. I do not have a multi meter as am not familiar with home electrics - I prefer to get a professional to deal with such things for peace of mind & safety.

Just a suggestion, but could you live with lower watt bulbs - 35W etc?

I had a similar problem at home and as previous posted suggested the transformers couldnt handle bulbs at 50w but are OK at a lower wattage. I also found that the transformers and fittings were covered with loft insulation:eek:

If it helps & makes things safer, I will definitely consider lower watt bulbs - I think they do them also in 20 & 35 watts - will it be OK to use 35 watt bulbs per light instead (12 Lights) with my dimmer switch?

I made sure that the insulation around the lights was removed but there are wooden boards above the lights which have lots of small holes drilled in above the lights for the heat to dissipate.

OP, think about LED's, plenty of good ones out there and they produce little heat, draw less power and give a lovely light. They are very expensive however.

Just had a look at LED's (did not even know they were an option!) - tbh, I have already spent a fair bunch on these bloody lights, transformers, dimmer & electrician charges so at this point in time, I just want to make everything safe & working OK - maybe in a few years, I will change everything over but for now I am stuck with things! I just do not want to go through the same routine again with a another electrician!

Guys, I am sorry, I did not mean to cause any arguments but just want things sorted at my end - having to rely on so called professionals, I just want to be armed with some correct info in order to ensure they check & do things properly this time & identify the problems - also I want to make sure I get the correct & proper things & need to know what to get so things do not keep blowing, transformers/bulbs failing & lights turning them selves on & off etc!! Of course, I also want absolute assurance there is not a fire or safety risk!

Suave!
 

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