Ask The Trades - NO BUZZING PLEASE!

Dusty Junior Member Offline Grrrrrrrrrrrr Posts: 39 Total Thanks: 0 For This Post: 0 Gender:	NO BUZZING PLEASE! Aug 11^th, 2004, 9:52am I�ve tried using dimmer switch, transformer, and LV down lights (ScrewFix bless�um) but they flicker and the switches buzz Can anyone tell me what gear will work properly and where I can get it Thanks Dusty
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HandyJon GDPR opt-out Total Thanks: 0 For This Post: 0	Re: NO BUZZING PLEASE! Reply #1 - Aug 11^th, 2004, 11:45am I suspect you might need a more powerful dimmer switch to stop the buzzing. The flickering is probably related to the lack of ummph^* available through the inadequate transformer in the switch. * - Technical term only experienced electricians understand.
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plugwash Administrator Offline I love YaBB 1G - SP1! Posts: 1383 Total Thanks: 0 For This Post: 0 Trade: Not Specified	Re: NO BUZZING PLEASE! Reply #2 - Aug 11^th, 2004, 12:42pm either an unsuitable transformer or an undersized dimmer how many lights do you have? what power each are they? what is the power rating of the transformer? what is the power rating of the dimmer? does the transformer explicitly say dimable?
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Lectrician Administrator Trade Member Author Offline Ask The Trades Posts: 8814 Total Thanks: 109 For This Post: 0 Braunton, North Devon United Kingdom Gender: Trade: Electrician	Re: NO BUZZING PLEASE! Reply #3 - Aug 11^th, 2004, 4:53pm Ensure the transformer is a dimmable type. Ensure the dimmer can handle low volt transformers, and that the max rating is exceeded (or indeed the min rating). All dimmers buzz unfortunatly, the dimmer the lamps, the louder the buzz. Oversizing a dimmer does lessen the buzz.
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rabbit_rabbit GDPR opt-out Total Thanks: 109 For This Post: 0	Re: NO BUZZING PLEASE! Reply #4 - Aug 11^th, 2004, 5:02pm Also - most dimmers have a MINIMUM rating as well as a MAXIMUM. If the dimmer states on rear side something like "60W to 400W" and you stick in a 40W bulb, say, the net result is the bulb flickers. RR
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Dusty

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Re: NO BUZZING PLEASE!
Reply #5 - Aug 11^th, 2004, 8:16pm

Thanks guys8)

So, if I want to fit 5 12v 20w halogen down lights Shocked

What should fit in the way of transformer & dimmer Roll Eyes

Transformers - ScrewFix offer 3 dimmable LV transformers ; 35-105vA, 50-150vA, 100-210vA, but which is best for my 5 lights Angry

Dimmers � there seams little choice, all the makes in the ScrewFix catalogue are the same rating 1G 2W 400W. If there are any other types, what do I look for and where ???

Thanks

Dusty

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The_Trician

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Re: NO BUZZING PLEASE!
Reply #6 - Aug 11^th, 2004, 10:44pm

Go for a transformer which is rated top-side of the job and go for one transformer per light fitting.
Don't try to run more than one light off a single tranny.
You should ensure that the tranny is suitable for dimming and if you are using 20w lamps, then go for a 50va tranny for each fitting.

5 x 20w = 100w so your dimmer switch should be rated at this. Better still, go for a 250w one.

TT

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ban-all-sheds GDPR opt-out Total Thanks: 8 For This Post: 0	Re: NO BUZZING PLEASE! Reply #7 - Aug 12^th, 2004, 6:31am Switch to mains halogens.
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Dusty Junior Member Offline Grrrrrrrrrrrr Posts: 39 Total Thanks: 0 For This Post: 0 Gender:	Re: NO BUZZING PLEASE! Reply #8 - Aug 12^th, 2004, 4:29pm Thanks, The_Trician So if I decide to change the plan and fit 8 downlights, are you suggesting I buy 8 transformers I'd like to stick with LV because I've heard they omit much less heat and you can fit more of them without installing separate circuits. Is this true. Thanks Dusty
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Lectrician Administrator Trade Member Author Offline Ask The Trades Posts: 8814 Total Thanks: 109 For This Post: 0 Braunton, North Devon United Kingdom Gender: Trade: Electrician	Re: NO BUZZING PLEASE! Reply #9 - Aug 12^th, 2004, 5:21pm Watts are watts regardless of voltage Best to use one tranny each, thats what we do. But you can use larger trannys and feed a couple of lights, but you need to be careful of volt drop (keeping cables short, and maybe increasing size between tranny and light).
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ban-all-sheds

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Re: NO BUZZING PLEASE!
Reply #10 - Aug 12^th, 2004, 5:32pm

[quote author=Dusty link=1092214325/0#8 date=1092324584]I'd like to stick with LV because I've heard they omit much less heat and you can fit more of them without installing separate circuits. �Is this true. Roll Eyes

[/quote]
Well - a 12V halogen of x watts is going to put out about the same amount of heat as a 230V x watt one.

And the current load on the 230V circuit will be slightly higher with the ELV lights, as you have transformer losses to consider. And as the current on the 12V circuit is approx 20x higher than the same amount of mains lighting would be, those cables need to be thicker.

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Lectrician Administrator Trade Member Author Offline Ask The Trades Posts: 8814 Total Thanks: 109 For This Post: 0 Braunton, North Devon United Kingdom Gender: Trade: Electrician	Re: NO BUZZING PLEASE! Reply #11 - Aug 12^th, 2004, 5:52pm Dont like LV then BAS LV : - 90% of heat fires backwards from the bulb, so cool to the front. - Light colour rendering is excellent, pure white. - LV lamps last longer
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Dusty

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Re: NO BUZZING PLEASE!
Reply #12 - Aug 12^th, 2004, 6:58pm

Lectrician 8)

May be the forum should conduct a debate/survey into which is best, mains or LV Grin

You also mention in an earlier post to "oversize the dimmer". The only dimmers I�ve ever seen are 400w.
That�s what I fitted the last time I installed a downlight and it buzzes and flickers like hell Shocked

Right now, I don�t know what I should fit, mains or LV. Wink

Thanks

Dusty

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The_Trician

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Re: NO BUZZING PLEASE!
Reply #13 - Aug 12^th, 2004, 7:26pm

Mains are much easier to install because there are fewer connections to make. Colour-rendering/degree of brightness is purely a matter of personal taste so can't help you there.

Don't forget that if there is a habitable room above the ceiling into which you are installing, then you'll have to fit a firecap to each light fitting to restore the fire-rating of the ceiling and meet Building regs. These are around �10+vat each and are an absolute must.

TT

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LSpark Global Moderator Trade Member Author Offline Posts: 8069 Total Thanks: 3 For This Post: 0 London, UK United Kingdom Gender: Trade: Electrician	Re: NO BUZZING PLEASE! Reply #14 - Aug 13^th, 2004, 5:26pm agreed with the fire caps, not sure why people refer to them downlighters as LV unless there mains voltage, 12V is Extra Low Voltage (ELV) not LV.
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Mice Junior Member Offline pass me the BIG hammer Posts: 69 Total Thanks: 0 For This Post: 0 Gender:	Re: NO BUZZING PLEASE! Reply #15 - Aug 13^th, 2004, 5:42pm Try these dimmers, no noise, LV or ELV, soft start and remote control. Used them in my last house with no problems. http://www.tlc-direct.co.uk/Main_Index/Lighting_Menu_Index/Wiring_Accessories~Di...
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scotspark Trade Member Offline mmmmm it's gonna cost you!! Posts: 3074 Total Thanks: 10 For This Post: 0 scotland Scotland Gender: Trade: Electrician	Re: NO BUZZING PLEASE! Reply #16 - Aug 13^th, 2004, 8:04pm when you dim ELV lights you allow for the load of the tranny not the bulb plus you must derate by 25% so 10 50watt lamps on seperate 60 watt transformers = 600watts so dimmer must be at least 800 watts with mains halogen lamps you must derate by 50% so 10 50 watt fittings = 500 watts so dimmer must be 1000 watts
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