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659 posts

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Topic # 154787 7-Nov-2014 15:14
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Purchased some sample COB (Chip on board) LED light MR16 from Aliexpress to see if they would run on our transformers.

Surprisingly they worked fine as it turns out we have 10W-60W 12V electronic transformers. Despite being 6W and 9W lights they still worked...so happy we dont have to replace the transformers

QUESTION

 

In the long term would 9W be fine \ safe to run on 10W-60W transformer ? will 1W difference burn my house down or ruin my bulbs ?

 

Im looking to get a mix of 9W and 12W warm whites and pure whites depending on where they are used.

 

 

 

 

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  Reply # 1171016 7-Nov-2014 17:17
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The load rating is the range where it meets EMC and efficiency compliance.  Outside the range is not guaranteed.  Too low and the voltage might also rise out of spec, too high and it may go into current limiting and wear out components.

You will be surprised how much overcurrent an LED can handle without failing for a long time, however the life time is significantly reduced and the efficiency goes down.  That is the trouble, often (including last week) "breakthroug" efficiencies of e.g. 300 lumen per Watt is announced when that efficiency is achieved only when the LED is run at say 20% of its rating.  When run close to rated power the efficiency is around 80 lumen per Watt period.  But I'm off on a tangent, my point is I've run a few hundred mA through a normal "30mA max" 5mm red LED and it did not burn out even after a few minutes.  The ultimate check is measure the voltage (and current if you can) to make sure it is in spec for the LED, and don't load the driver too much.




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  Reply # 1172242 10-Nov-2014 14:51
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Electronic transformers hate running LED's with their own power supply in them.

IMO 12V leds should only ever be run on a magnetic transformer.

Depending on what the power supply in the LED does, it may cause the "transformer" to run quite hot as its pushing it into operating inefficiently. they only ever test those power supplied into an incandescent load, and check they dont overheat etc when shorted and overloaded with incandescent lamps/other resistive loads.

If the lampholder is floating in the fittng, you can get GU10 holders with wires and an enclosed terminal block for quite cheap, and then just replace the transformer with the GU10 holder. That way you have a chance that dimming will work as well.




Richard rich.ms



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  Reply # 1177941 18-Nov-2014 13:48
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Thanks for info I ended up getting 9W pure white for all the outdoor lighting and bathrooms. 12W Warm white for kitchen, dining, lounge, family.

Next issue is the 12W LEDare about 10mm to tall to fit into light fitting.

Is it acceptable with LED (due to low heat) to cut out top of the light fitting and have the ceramic holder outside of the housing ?. If not I worked out that I can buy some aluminium mesh to make the cage taller, but the drilling top looks far quicker (just needs to be safe)



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  Reply # 1177975 18-Nov-2014 14:36
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Further to above post the question is

 

do 12V MR16 Led bulbs with heat sinks integrated into their base require a heat cage over the top of them like halogens do ?

If not my height problem is solved simply by removing the cage on top of the fixture altogether.

My testing of the 9W bulbs netted about 40 degrees C after running them for 2 hours straight, ie I could hold the bulb, heat sink and all in my hand.



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  Reply # 1178027 18-Nov-2014 16:21
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heylinb4nz: Thanks for info I ended up getting 9W pure white for all the outdoor lighting and bathrooms. 12W Warm white for kitchen, dining, lounge, family.


got any links to the actual units you purchased?




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Ultimate Geek
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  Reply # 1178047 18-Nov-2014 16:59
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Regs:
heylinb4nz: Thanks for info I ended up getting 9W pure white for all the outdoor lighting and bathrooms. 12W Warm white for kitchen, dining, lounge, family.


got any links to the actual units you purchased?


Yep this supplier here, 12W version

http://www.aliexpress.com/item/2014-new-1pcs-lot-high-power-MR16-12V-6w-9w-12w-led-Dimmable-cob-spotlight-lamp/2022578378.html





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  Reply # 1178310 19-Nov-2014 09:27
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Last night I run my 12W bulbs for 2 hours and used digital temp gauge to get reading

 

- Heat fins \ sink 47-50 deg C
- Bulb face 36 deg C
- Ceramic connector 35 deg C

Based on this I don't see any reason I couldn't run the bulbs without the cans in the ceiling.

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  Reply # 1179518 19-Nov-2014 13:32
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You are still modifying a fitting, and you have no idea that someone wont get sick of the LED and put a 50w halogen in the fitting at a later stage.

Downlights are dirt cheap. I got some decintish looking HPM branded white ones from bunnings for under $20 each, with a GU10 LED lamp in the box. Without a lamp is even cheaper than that. If you modify the lamp and something else catches fire like the power supply or whatever expect fingerpointing at the lamp with the back chopped out of it.




Richard rich.ms



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  Reply # 1179541 19-Nov-2014 13:58
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richms: You are still modifying a fitting, and you have no idea that someone wont get sick of the LED and put a 50w halogen in the fitting at a later stage.

Downlights are dirt cheap. I got some decintish looking HPM branded white ones from bunnings for under $20 each, with a GU10 LED lamp in the box. Without a lamp is even cheaper than that. If you modify the lamp and something else catches fire like the power supply or whatever expect fingerpointing at the lamp with the back chopped out of it.


Problem im facing is the whole house (bar bedrooms) is fitted with MR16s (about 35 in total) so anything I do needs to be cheap....

 

- Retrofit 12V LEDs @ $79 each (no go)

 

- Converting back to GU10 240V = electrician bill of $1000+, + cost of 35 GU10 fittings

 

- Going to standard LED E27 style fittings, same as above, electrician + new fittings.


Basically im stuck on 12V transformers and MR16 fitting.

 

but as you say whatever I do needs to be compliant.

 


For about $60 I can get aluminium mesh and pop rivit gun and add extra 30mm height to the existing cage, which will retain the covered dome on top, this will allow plenty clearance for the bulb base and ceramic connector inside (same as if running a Halogen).

Going by my 47deg C on heatsink running hanging out of fitting, im most likely looking at 60-65 deg C in the confines of the recess...which is on par with LED optimal temperature for longest bulb life.

 

Regulation aside, those MR16 halogens get super hot, you'd think a bare heat finned MR16 LED running at 47 deg C would be better safety trade off than MR16 Halogens running in compliant recessed cages and pushing well over 100 deg C.

Note: seems I have Bradford Gold Insulation which is 4 zero fire rated and actually resists \ impedes fire, so not like 47deg C is going to set it off.


 

 

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  Reply # 1179561 19-Nov-2014 14:29
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I've bought LED lights for the whole house from here:

http://www.lightpower.co.nz/

The guy running the shop is an actual sparky, not just a reseller so he knows his stuff.

still doesn't offset the cost of running a VMware farm & san.....



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  Reply # 1179664 19-Nov-2014 15:53
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mattk: I've bought LED lights for the whole house from here:

http://www.lightpower.co.nz/

The guy running the shop is an actual sparky, not just a reseller so he knows his stuff.

still doesn't offset the cost of running a VMware farm & san.....


Some of the more reasonable prices ive seen, plus the added incentive of a warranty and sparky advice.

Bunnings sell the Switch brand of 7W LED GU10 4 pack for $39.95, I replaced my 50W halogens in our outdoor spot lights and they were brighter. That's what inspired me to do the inside lights as well.

Im still not game enough to shell out $19 for a 6W MR16 when the same bulb in 12W on Aliexpress is $4.50 shipped. I might buy one though to dissect and compare.

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  Reply # 1179669 19-Nov-2014 16:07
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I have purshased a number of different LED bulbs in an attempt to swap out the orginal bulbs, but none work, I am assuminmg because of the tranformers I have (most are the possum brand), at best I get a flick of light, then nothing, should they work?



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  Reply # 1179679 19-Nov-2014 16:20
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nicmair: I have purshased a number of different LED bulbs in an attempt to swap out the orginal bulbs, but none work, I am assuminmg because of the tranformers I have (most are the possum brand), at best I get a flick of light, then nothing, should they work?


Luck of the draw I suppose.

Our ones (house built in 2009) are budget lighting direct electronic ones and were rated 10W-60W. BUT

Ive tested 6W, 9W and 12W ones in them (from supplier in my link) and they have all worked fine.
Its possible you have 20W-60W transformers so even a 12W LED is to far out of range to work. The link above (http://www.lightpower.co.nz/) to nz LED supplier had reasonable priced LED drivers at $12.50 each.

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  Reply # 1179680 19-Nov-2014 16:21
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That means the powersupply is shutting down. Replace them with a magnetic one or a LED power supply and you should be sweet.

Even with enough LED to meet the minimum load on an electronic power supply made for incandesent lamps, they will often not start. A LED replacement with its own filtering etc can present a signifigant inrush current as its filter capacitors are charged up.




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  Reply # 1179685 19-Nov-2014 16:24
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If you live in the house, then you can replace the light fitting (with similar type) yourself as long as you don't change (extend) wiring.  No need for an electrician.

http://www.qualityledlighting.co.nz/
Electrician in Wellington that got fittings certified to NZ-specific standards.  You can pick the exact colour temperature you want (we got 4000K).  I've replaced ~30 fittings in my house, just did not bother with the garage and outside.  Cost a fair bit, but done once and done right with good quality parts locally supplied at a reasonable price.




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