Cable required, 4 x 7w LED globes on a 12VDC circuit.

Thread Starter

extra_g

Joined Dec 31, 2020
7
I wish to run 4 x 7w LED globes in in parallel using one 12VDC power supply. What cable would I need to safely do this?
 

wayneh

Joined Sep 9, 2010
17,152
Standard lamp cord. A lower gauge is a thicker wire, and more (thickness) is better. So a 14 gauge would also be OK, but not an 18.

Don't forget the mechanical properties, for instance if there is contact with the ground, exposure to sunlight, rodent bites and so forth.
 

Thread Starter

extra_g

Joined Dec 31, 2020
7
16 AWG is larger than I anticipated, I am currently feeding the transformer 240VAC using 16AWG or 1.5mm cable. I guess then I can use the same cable from the transformer to the lights then.
I currently have 4 x iron core transformers powering 4 x 7w LED. They use to power 50w halogens, plan is to run all 4 LED of the one transformer.
 

wayneh

Joined Sep 9, 2010
17,152
16 AWG is larger than I anticipated, I am currently feeding the transformer 240VAC using 16AWG or 1.5mm cable.
28W at 240V is just 117mA. So 16 gauge for 1.5m is "overkill" based only on the amperage. But again, 16 is a standard and there's nothing wrong with overkill.
 

MisterBill2

Joined Jan 23, 2018
8,752
#18 wire is a very common size for electrical appliances, I have a power washer with a 15 foot cord of #18 wire, and that is no problem at all.And #18 is both more common and a lot cheaper than #16 wire.
 

wayneh

Joined Sep 9, 2010
17,152
@MisterBill2 is correct and I misspoke earlier: standard lamp cord is 18 gauge. And it’s fine for a 2-3A load. That’s 240-360W on a 120V supply, and not unusual for a lamp.
 

BobTPH

Joined Jun 5, 2013
3,308
The chart I looked at gave 2.3 as rhe max Ampicity of 18 gauge wire, so right on the edge for this application..

Bob
 

wayneh

Joined Sep 9, 2010
17,152
The chart I looked at gave 2.3 as rhe max Ampicity of 18 gauge wire, so right on the edge for this application...
For the 20ft., I'd also prefer going bigger. But a 300W bulb on a typical 6' lamp cord used to be a pretty normal thing.
 

MisterBill2

Joined Jan 23, 2018
8,752
W are talking about a power cord, NOT about a bunch of wires in a conduit in a high ambient area. There are a number of different ampacity tables that depend on the environment and the insulation.
 
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