Can someone help me with what driver I need?

[ETradesmen]

Hi guys (can I assume pronouns?!?!?!!), I’m in need of a certain LED driver for the attached LED lights.

The problem I have is that I’ve wired these in 12V alarm cable from the loft and not allowed for 230v drivers at the fittings.

They come with individual drivers and there are 3 lights in total. Ideally would like 1 driver doing all 3?

I’ve attached some pictures, thank you in advance!

 

[westward10]

Why would you wire them using alarm cabling, I'm sorry but that seems a bizarre thing to do. Are they separated from any Band II cables.

 

[ETradesmen]

Why would you wire them using alarm cabling, I'm sorry but that seems a bizarre thing to do. Are they separated from any Band II cables.

I wire all my LED lights in 12V cables as I haven’t got to worry about wrestling twin and earth cabling through a 24mm hole and attaching a driver. Also leaving access to one driver in the loft is easier than leaving access to 3 separate drivers which will more than likely get tiled over by a numpty.

The customer has bought these without consulting me first.

Yes, the cable isn’t near any mains cables.

Regards, Michael

 

[Lucien Nunes]

Can't you simply relocate the three existing drivers to the other end of the ELV cabling, all in one place?

If you do want to operate all three from a single driver then as we don't know the voltage of the LEDs themselves, we have to go with what we know from the existing drivers. These are 300mA constant current with a voltage compliance of 6-12V. If you wired all three LEDs in series you would need a 300mA driver witth voltage compliance of 18-36V.

 

[DPG]

Watch for volt drop issues as well.

 

[Lucien Nunes]

Although as it's constant current in this case, unless the VD pushes the total voltage beyond the compliance of the driver, it won't affect operation. Normal alarm cable is about 0.2mm² and 0.2 ohms loop per metre. At 300mA that allows 17m of cable per volt of drop. If it's say 6-core with 3 cores paralleled for pos and neg, and let's say there's 4V overhead between the total LED forward voltage and the available driver compliance, that would give a total of 204m of cable before it becomes a problem.

 

[DPG]

Although as it's constant current in this case, unless the VD pushes the total voltage beyond the compliance of the driver, it won't affect operation. Normal alarm cable is about 0.2mm² and 0.2 ohms loop per metre. At 300mA that allows 17m of cable per volt of drop. If it's say 6-core with 3 cores paralleled for pos and neg, and let's say there's 4V overhead between the total LED forward voltage and the available driver compliance, that would give a total of 204m of cable before it becomes a problem.

True. But should be considered. And I bet the cores aren't paralleled!