LED Driver to Light Cable Spec

[RJH]

I've just been trying out a couple of 3W undercounter LED lights that I have, and a 10W driver unit. To see if it works I've made up a couple of cables using JST connectors, and some lengths of stranded (5 or 6 strands) wire from an ethernet cable. I've got some thicker cable but I used this for convenience

- I'm not the most skilled at making up connectors.

I suppose I should get something more suited, and while it does work and nothing's gone up in smoke, is this wire sufficient spec for the purpose?

[Theo]

What voltage are the lights being driven at? Does the driver have that written on it?

Often such things are a long string of LEDs in series, driven by a constant current driver. The voltage can get quite high, nearing mains, if there are enough in series. Other lights have LEDs in parallel so the voltage is low.

If you know the voltage and current you can find out if the insulation of the wire can handle it, and whether it can handle the current.

Theo

[jon]

Depends on the power of the leds, not all leds are the same.

[RJH]

Ah, yes, 24V.

They're those strip undercounter lights.

From the spec sheet - Voltage 24 VDC, max total load 0.42A, 10W

[RJH]

One's 3W, the other's 4W. Spec of the driver as I just posted - Voltage 24 VDC, max total load 0.42A, 10W.

As I say, everything seems to work . . . but for how long?

[Theo]

Power over ethernet goes up to 48V and 350/600/960mA per pair. So, while that wouldn't be my first choice of wire (quite fragile), you should be ok.

Theo

[Animal]

If the wire's not getting warm it's fine. If it is a bit warm, you could double up conductors. If it gets hot, use thicker wire.

[The Natural Philosopher]

Look up the power over Ethernet spec. I am pretty sure that CAT5E is able to deliver all that and more. But Ethernet cable is normally solid cored, or do you mean a drop lead?

"The original IEEE 802.3af-2003[1] PoE standard provides up to 15.4 W of DC power (minimum 44 V DC and 350 mA) on each port. Only 12.95 W is assured to be available at the powered device as some power dissipates in the cable."

(Wiki)

That implies there may well be a bit of a voltage drop on a long run, but apart from that no big deal. 350mA at 12V is a bit over 4W

It's like some 12V (halogen) spotlight lights I have that use a bit of lighting T & E after the 12v transformer. They are rather dimmer than normal, and I will replace them with LED when they go, but they haven't gone in 20 years despite being in daily use :-)

[The Natural Philosopher]

Pretty much in spec for CAT5

There will be a slight loss in the cable, depending on length. It wont burn out or get hot.

[The Natural Philosopher]

+1

[RJH]

patch cable? - yes.

It's only a couple of feet.

[alan_m]

You are probably OK with your wire but another option is twin wire, sold as speaker cable Example

13 Strand: 2.5A maximum (With 24V that's around 60W) One wire has a black line to identify it.

[RJH]

Thanks - yes, that looks better (and less fragile).

I had tried with some speaker cable, but with about 40 strands. Tricky to get them into the connector housing so I threw in the towel on that idea. The ethernet cable has about 10 strands of very fine wire.