Installing an LED transformer

[johnwatters7]

I had a couple of transformers go on halogen spotlights. I'm the in the process of switching to LEDs so I bought LED transformers instead.

The old transformers had a blue and brown wire on the input AC side which were connected directly to the same colour mains wires in the connection box.

However the new LED transformers only have a brown and black wire on the input side. I connected brown to brown and black to blue and it seems to be working fine albeit with a second delay before the spotlight comes on.

Is this the correct thing to do? Does it even matter with a transformer?

Many thanks

 

[bernardgreen]

so I bought LED transformers

To be precise you bought power supplies for LEDs. Connect LEDs to a real transformer and they will be destroyed. Power supplies for LEDs are DC with either constant current or constant voltage outputs.

 

[JohnW2]

Power supplies for LEDs are DC with either constant current or constant voltage outputs.

We always say that, and I'm probably as guilty as anyone else. However I wonder if there actually is any 'consumer use' for a constant-current supply - i.e. are there any 'consumer' LED lamps which do not have built-in current control (i.e. intended to be used with an essentially constant-voltage source)??

Kind Regards, John

 

[333rocky333]

However I wonder if there actually is any 'consumer use' for a constant-current supply

Likely not,, as you say, in cases like this were the lamps are bought and being fitted seperate, usually GU10 or GX5.3.

However in domestic cases were a fitting supplied with the lamp "fitted" in has failed and the consumer wants to try replacing the "Transformer" then that "Transformer" as you know could well be "constant current".

Im not aware of any "standard" Plug In type lamps to work with these they all tend to be wire in types or non standard plugs

They dont seem to be popular in the domestic sector yet, I assume because of the number of existing fittings, that are basically just 50mm lamp housings, already fitted that are being easily uprated to Led.
No doubt in the future there will be posts regarding "Constant current" transformers, where they have failed prematurely to the Led element, certainly seems the case in commercial lighting

 

[JohnW2]

However in domestic cases were a fitting supplied with the lamp "fitted" in has failed and the consumer wants to try replacing the "Transformer" then that "Transformer" as you know could well be "constant current". .... Im not aware of any "standard" Plug In type lamps to work with these they all tend to be wire in types or non standard plugs

Quite. It may well be (probably is the case) that there are some light fittings that use essentially 'bare LED elements' with a constant current-supply as part of the fitting which is external to the lamp but internal to the fitting - not that I know where I could get LED Lamps which were "essentially bare LED elements".

However, that is rarely, if ever, what we are talking about here. We are almost invariably talking about external standalone power supplies ("transformers") used to feed an ELV fitting (which contains standard 'LED lamps' with built-in current control) - so I don't really see how/why a constant-current version of that would ever be appropriate in a domestic/'consumer' setting.

If LED Lamps which were "essentially bare LED elements" with standard bases were ever to appear on the consumer market, then I imagine that there would be an awful lot of "bangs"!

Kind Regards, John

 

[endecotp]

the new LED transformers only have a brown and black wire on the input side. I connected brown to brown and black to blue and it seems to be working fine

That's surprising, as I think it's a regulatory requirement that the standard colour scheme (brown/blue/green-yellow) is used.
It may indicate a low-quality product with potential safety issues.

Did they come with any instructions?
Are there any markings giving any suggestions about how they should be connected?
Where did you buy them from?

 

[endecotp]

Guys, you've gone off on your predictable "transformer" rants without even answering the actual question.

 

[flameport]

Is this the correct thing to do? Does it even matter with a transformer?

Doesn't matter, it's an AC input so there is no concept of 'correct polarity'.

 

[flameport]

that there are some light fittings that use essentially 'bare LED elements' with a constant current-supply

Collingwood used to make and supply such things, typically 1W LEDs in aluminium housings, several of which were connected in series to a constant current 350mA supply.
Their only supposed benefit was the saving in only requiring a single driver unit for multiple LEDs. Every other aspect of them was a disadvantage.

 

[JohnW2]

Collingwood used to make and supply such things, typically 1W LEDs in aluminium housings, several of which were connected in series to a constant current 350mA supply. Their only supposed benefit was the saving in only requiring a single driver unit for multiple LEDs. Every other aspect of them was a disadvantage.

Indeed. As I said, I did not doubt that such things existed, but I still do doubt that they have any relevance to domestic/consumer lighting/products. I just wonder what these "constant-current PSUs/drivers" we're always mentioning to DIYers are actually all about!

Kind Regards, John