sitting room light humming

thetourist

i spent a strenuous 2 hours last night installing a pretty complicated ( and expensive - 300e ) light into our double height ceiling in the sitting room only to discover when i turned it on that it sounded like a dodgy marshall stack - now i shorted out the dimmer switch and a lot of the buzz went away but i was still left with a low pitch hum - which im sure a lot of people would not even notice but both me and the missus think it's a bit intrusive - my question is this - do all of the lamps with transformers have a hum out of them and if we want one of those fancy things with 12 little bulbs on there is there any way to get it working off 220 v bulbs so we can get away from transformers...........once bitten twice shy ........


checked out the recessed bulbs on transformers in the main bedroom and when you adjust the dimmer they hum too - except that it's liveable with

kenmc

AFAIK transformers always hum.

themole

ya, all transformers humm, especially mains ones.

you could lengthen the cable either end of the transformer and find somewhere else in the ceiling/wall to hide it. maybe some sound insulations stuff could do the trick?

there are strip lights you can get without a transformer, they tend to be larger though. check out a hardware store and as them

rooferPete

Hi,

My knowledge of the electrical trade is very limited and to be honest I want to keep it that way, I firmly believe it is an area where a little knowledge can be very dangerous.

That said I was advised not to use dimmer swithes with downlighters unless using 220 volt units and even then there can be an issue with the bulbs blowing.

It could be a good time to check with your electrical wholesaler or better again your RECI Electrician.

thetourist

RECI Electrician

mmm - that's the guy that convinced me that the best way to do downlighters was on a transformer --- and he put in a dimmer switch for me too

Stoner

Gumboots,

LV lights c/w traffos should not hum. If you have a traffo that is rated high enough to carry the load. i.e if you have 200Watts of load you need a 250W traffo to be sure. So if you have one of those fittings with loads of 50Watt lamps it should have a decent sized traffo.

I do not recommend adding length to the secondary side of traffo (between the traffo and the lamp) this cable should be very short as they tend to cook due to the high currents that flow here (220/12 = 18) so you have about 18 times more current on this side of the traffo then you do on the other side (mains to traffo)

the next thing is the dimmer switch, is this rated highly enough, if some buzzing was prevented by bypassing the unit then it sounds like you may have an under-rated dimmer ( but a dodgy load can also cause this)

My guess / soultion is to over engineer it, over rate the traffo, over rate the dimmer.
I also dont like the 220V GU10 spots, we do alot of apartments in and we do not install them, they run very hot and dimmer by about 30% compared to LV and they dont last long before blowing.
If the traffo is wirewound you could change each lamp to LED ( about 20 euro each) but they run at a fraction of the cost and will last about 15 years ( only about 50% output but if its only feature light then your in biz) they can also run direcly from 220 V ( the best way ).
Essentially it sounds like either the switch or the traffo. Expensive fittings does not equal good quality in my experience, some of the worst looking connections i have seen have been on expensive fittings and sometimes you have to change the traffos, it would not really be the electricians fault as nobody wants to change stuff like that from an insurance point of view, sometimes people spring sh_t fittings on sparks and expect them to take ownership of it and install it regardless, the poor quality issue with the fitting is reflected back on the workmanship of the tradesperson ( please note I am neither a memeber of a union or an electrician, i just work very closely with electricians LOL)

Alun

Stoner wrote:

I also dont like the 220V GU10 spots, we do alot of apartments in and we do not install them, they run very hot and dimmer by about 30% compared to LV and they dont last long before blowing.

It depends a lot on the quality of the bulbs. The bulbs that are supplied with these systems are often cheap and of low quality.

We've got a four light GU10 system in our living room and we've replaced a grand total of two bulbs in four years.

Stoner

Maybe so, it all depends i guess, but we put in a huge amount. GU10s are not really what people should put into their homes. We have installed anything up to 10,000 in the past 2 years , as everyone wanted to go with them, pluss from an installation point of view they save one connection per fitting. They blacken ceilings even faster then LV lighting. In my house I had 10 Watt and 13 Watt recessed PL fittings installed. these are brighter then an LV and only run at 20% of their power.
the call back ratio on GU10s is very high, we have similar quality issues with LV traffos, we only get IBL 5 year life traffos, as it saves us in the long run on call backs. If a room is cool, or if the ceiling in which the fittings are recessed into is ventilated then fittings will last longer, but this in not always the case so they cook and blow.
An example of how much of a difference ventilation makes, 16 years ago a 200watt halogen security light with an open face (no glass not legal anymore) was installed on my mothers house. It is on a sensor and goes on and off every night, the lamp has never been replaced. If it was covered in then you'd expect two years tops.
All i can say is try out the LEDS 15 year life cycle and they need about 5 Watts

Alun

Well, I can only go on my own experience FWIW I chucked the cheapo eastern european no-name bulbs that came with the fitting and fitted GE ones. These aren't recessed lights, so maybe heat buildup isn't such an issue there.

thetourist

thanks for all the input guys

first of all - the light in question is one single unit ( with 12 individual bulbs ) - not a collection of spots

the transformer is built into the unit

the unit/transformer cost 300euro which to me implies that i should have gotten a unit which didnt hum ( at least according to stoner anyway decent transformers dont hum)

i replaced the dimmer with a regular switch to remove that element - and the thing now hums instead of buzzes -- it it louder than the fridge

none of this has anything to do with an electician - that was a different room - and HE was the one who insisted on putting the spots on transformer - even though the room was already on a dimmer - but none of that is an issue at all because the buzz in that room is barely audiable

the bulbs were the bulbs that came with the unit - i havent checked but afaik the transformer is properly rated against the bulbs - is someone suggesting that the bulbs might be the cause of the hum

total wattage is 240w - transformer is of the toroidail? type

thanks for any input

thetourist

update - i removed the light from the ceiling and to cut a long story short i have discovered that there is a hum and a buzz - the hum was actually nothing to do with the light and more to do with the carpentry in the apex of the vaulted ceiling - apparantly the woodwork was acting as an amplifier -- and the buzz is solely to do with the dimmer ---- now i have to talk more with the guy who sold it to me but he did mention that possibly i might need a special dimmer for that particular light --- meanwhile i have discovered a very nice remote control dimmer which is "suitable for trailing edge transformers ... but not suitable for wirewound transformers " ---- does anyone have any ideas which my transformer would be because if the dimmer was compatiable then i would like to buy it

thanks
:cool:

thetourist

in the end i opted for a light with mains halogens - there's less of a choice - but it was the only real option in the end

Stoner

Sorry I blanked you before about your traffo type gumboots. hope it looks well