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120V AC with 18 AWG Stranded Wire on Power Supply

6118 Views 3 Replies 3 Participants Last post by  TeeRiddle
Hi all!

I purchased a LED strip light kit for adding under cabinet lighting in my kitchen. It's a direct wire power supply. My plan is to use a dimmer wall switch connected to the power supply. The power supply input is 120V AC with 12V DC for the output to the LED tape lights.

I was planning to use 14 AWG solid from the switch to the input of the power supply. The power supply comes from the manufacturer with 18 AWG stranded wire for the input and output. I'm fine with the 18 AWG stranded for the 12V DC output, but am worried this is quite "light" for the 120V AC coming into the power supply.

Is the about 6" of 18 AWG stranded ok for the 120V AC input?

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The 18 gauge leads of the power supply are okay.

They are connected (wire nutted) to the #12 etc. wire ends. Code (the tap rule) permits something like 18 inches worth of wire less than #14 to get from the usual #12 etc. conductor to the lamp socket, power supply transformer, etc. within a box or via conduit.

The power supply does not draw enough amperes to overload the #18 leads. That is all that counts.

The thinness of the #18 leads will start to cause a problem on the low voltage side first due to voltage drop. You might need heavier wire depending on how long the low voltage run is and how many amps at the low voltage you will draw. The existing 6 inch or so #18 low voltage wires can stay as-is and the fact they are furthest upstream will not nullify the benefits of fatter wires, if any, continuing on.
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I hate those power supplies with the leads. Make it really hard to do properly and to code. To do it right you'd really need to put the driver in an enclosure.

I like these:
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Thanks for your reply, AllanJ. I plan to use 16 gauge stranded from the power supply to the light strips and from strip to strip between cabinets. I will pre-run everything to check for voltage drop, especially for the strip that is last in line and farthest away from the power supply. My kitchen isn't that big and I think it will be about 25 ft (or so) in total length.

Thanks, Speedy Petey. The power supply is in an enclosed metal box without knockouts for the wire intrusions. I like the power supply you linked to, but it requires an outlet. I guess in some ways that would be better than direct wiring the power supply. I'm planning on mounting the power supply in my attic right above the first cabinet so it will be out of the way.
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