External light wire gauge

[CaptainJack88]

Hey All,

I've got 12x 24V 7W outdoor spike lights for my garden, the plug and play variety that only require a driver to be fitted. Electrician has already come and fit all the outdoor electrics, so will be back at some point to wire in the LED driver, but I'm questioning how the lights and their plug & play wiring is suitable.

- 12 lamps @ 7W = 84W, and I've got a 100W 24V driver
- 84W @ 24V = 3.5A
- The furthest lamp away from the driver is probably about 20m

Allowing for 5% voltage drop, doesn't this mean the cable needs to be 14 AWG or 2.5mm² ?

The tails and cabling that came with the lights is only 1mm², and the driver cables are only 1.5mm². Am I overthinking this, or are these lights not as plug and play as they would appear?

 

[ericmark]

It will depend on the drivers in the lamps, a driver is a device to limit the current going through an LED, it can be a simple resistor, or with AC a capacitor, or it can be a full switch more power supply.

So bulbs (LED and driver combined) sold for use in cars can have a massive 10 - 30 volt input DC, but some lamps sold for use in homes, the 13.8 volt found on many 12 volt batteries with caravans and boats is too high and can damage the bulbs.

The use of a driver of say 340 mA and variable voltage say 5 to 70 volt to supply garden lamps will auto compensate for any volt drop. But the use of a 24 fixed voltage power supply to then feed the driver in the bulb, it all depends on the bulbs built in driver, there is no way with info given to know if it will work or not.

However thin cables in gardens are easy to damage, so using a heavier cable can be a good idea.

 

[CaptainJack88]

Hmm thanks. Unfortunately there appears to be no information on what is actually driving the lamps themselves. Technical information on the is... Limited

The wires etc will be off the ground and pinned so not too concerned about them getting damaged, just want to make sure I've got the suitable wiring.

The lights themselves are these:

https://www.gledopto.com/h-col-381.html

Looking at the hue lights, their 100w driver has 2 outlets, each with a max of 30m and a total of 100w overall, but they're gauge is 1mm2, however makes sense after what you've mentioned above.

I guess the worse that could happen is the last lights in the chain are dimmer or don't work properly?

 

[Adam_151]

Theres a labelled drawing on that side about 2/3 of the way down that has a label pointing to the back of the fitting with the label "Power supply - Stable and durable" So I would assume there is some kind of DC to DC converter in there, and as they are nomally self regulating then if the supply voltage goes down, they'll keep the same output, but end up having to draw more current to maintain the wattage output, while will sag the voltage a little more but they will compensate and find equlibrium.... untill the point at which you go too far and they cant.

I said imagine over typical garden distances, they will work fine, but you cant cannae change the laws of physics (,Jim) so you will have more power being wasted warming the cable slightly over having a larger one. If you are using the supplied plug and play bits then I'd not worry at all because its obviously been designed and tested to work with them, but if you are going longer than that, I'd try and go up a size or two, or at the very least, test it on the bench first

[predantic mode]The device that is feeding 24v down the run of cable is just a power supply, the drivers are built into the fittings. Some times the bit you wire into the mains will be a driver, but not this case - a Driver will connect straight onto the LED/LED array to 'ahem' drive it, which is clearly not the case here, as it looks like each one has a miroprocessor controlling various banks of RYG diodes, while having much more computing power than the systems that landed the apollo missions on the Moon - just so that you can change the colour of your garden lights from your mobile phone )[/predantic mode]

 

[CaptainJack88]

Theres a labelled drawing on that side about 2/3 of the way down that has a label pointing to the back of the fitting with the label "Power supply - Stable and durable" So I would assume there is some kind of DC to DC converter in there, and as they are nomally self regulating then if the supply voltage goes down, they'll keep the same output, but end up having to draw more current to maintain the wattage output, while will sag the voltage a little more but they will compensate and find equlibrium.... untill the point at which you go too far and they cant.

I said imagine over typical garden distances, they will work fine, but you cant cannae change the laws of physics (,Jim) so you will have more power being wasted warming the cable slightly over having a larger one. If you are using the supplied plug and play bits then I'd not worry at all because its obviously been designed and tested to work with them, but if you are going longer than that, I'd try and go up a size or two, or at the very least, test it on the bench first

[predantic mode]The device that is feeding 24v down the run of cable is just a power supply, the drivers are built into the fittings. Some times the bit you wire into the mains will be a driver, but not this case - a Driver will connect straight onto the LED/LED array to 'ahem' drive it, which is clearly not the case here, as it looks like each one has a miroprocessor controlling various banks of RYG diodes, while having much more computing power than the systems that landed the apollo missions on the Moon - just so that you can change the colour of your garden lights from your mobile phone )[/predantic mode]

Yeah that's fair enough. I'll keep an eye on them, worse case, I'll have to split them up and install another outdoor socket and power them from the other side.

As for the pedantic note, that's a fair statement. I was looking at them, the meanwell supply I have says led driver on it so just went with that

 

[SFK]

I have 25m of 1.5mm rubber cable supplying several 12V led spots from a 12V DC supply.
I know (as I measured it) there is a voltage drop of a couple of volts, but I cannot visibly see any dimming of the lights down the garden.

I reckon you will be fine.

I would suggest you simply plug then in and see. You could test it beforehand by putting your voltage supply at one end of your cable and the light at another (my roll of cable had both ends visable so I did not need to un-wind it.

Sfk