24v DC 75w led strip cable size sanity check

[jacko555]

I've purchased kit for a dimmable led strip. I forgot to buy cable.

I have 75w of light strip at 24vdc.

Intention is LED driver feeding one strip over a bay window - 3m of strip at @ 45w, then hidden cable for 4m, then, 2m strip @ 30w.

Supplier sells 22awg cable as "compatible".

A random awg converter online says 22awg = 0.32 mm2 cable.

So doorbell cable should be ok? 0.4mm or higher. Stranded or solid? Or does it really not matter?

 

[EFLImpudence]

Watts divided by Volts = Amps.

 

[jacko555]

I am aware of this relationship. I am not sure of the correct cable size to safely use.
The IET On Site Guide to wiring regulations 17th Edition (cheers google) says 1.0mm cable, when clipped, has a max of 15.5 amps.
So my puny 3.125amps sounds ok for a 0.4mm cable.
Although seeking clarification

 

[EFLImpudence]

Well, 0.5mm² flex is only rated at 3A in the wiring regulations -

although auto wiring does not seem to follow the same ratings.


Does the seller not quote the amperage of what you are buying?

 

[EFLImpudence]

For example:

https://www.ebay.co.uk/itm/12v-24v-...4e64a6a621e0cf61809f|ampid:PL_CLK|clp:2334524

 

[jacko555]

Amperage of the driver is listed at 24V 1.4 ~ 4.2 amps.
Its a 100w dimmable driver, with 75w of led.

I guess then 0.75 mm2 @6 amps rating, if 0.5mm2 is borderline.

Safe?

 

[flameport]

Safety isn't the main consideration - it won't be dangerous even with undersized wires.
The main thing is volt drop - even a small drop will result in the second strip being noticeably dimmer than the other one.

If the supplier is selling wires sized in AWG, it suggests the rest of the items probably don't meet any decent standards either.

 

[jacko555]

I ran a volt drop calculator, apparently 0.17v over 9m 1.0mm2 cable, and, 0.07 over 4m.

I'll guess I'll suck it and see.