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I am installing some landscape lighting. The kit came with 14 AWG wire. I have 10 lights at 11 watts apiece and a 150 Watt power pack. I need a few extra feet of wire and have some 16 AWG laying around.

Is it OK to mix the 2 sizes?

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1 Answer 1

Generally its not OK. You don't say whether the power pack is 12 or 24 VAC.

  1. 110W / 12 V = 9.16 A
  2. 110W / 24 V = 4.53 A

AWG 14 wire is rated for 15A

AWG 16 wire is rated for 8A

So, if you are using a 12 V power pack, 16ga is too small.

It would be technically OK, current-wise, for 120VAC, but I don't know of any 16ga wire rated for distribution outdoors.

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Isn't 14 gauge wire used for 15amp circuits? –  Steven Jun 24 '13 at 22:26
    
@Steven You are correct.. that table looked right.. will update answer –  HerrBag Jun 24 '13 at 22:56
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You also need to take the distance the wire will be traveling into consideration (since this is landscaping). Runs of 1000 ft for 14 Ga wire have about 3 ohms of resistance. Assuming 3% drop in circuits (suggested by NEC) and 9 Amps. Means that you are only going to be allowed .04 ohms loss. (12V*.03)/9amps=.04. This means you should only be able to go 20 feet with 14 ga wire. The 16 gauge wire gives you about 10 ft. –  Matt Johnson Jun 25 '13 at 8:23
    
@MattJohnson You are right from an effective lighting standpoint (having enough voltage per bulb). I was concerned that a 12v system would force too high a current for 16ga. More 14ga might give slightly less light per bulb (higher loop resistance means lower current) but would be safe. –  HerrBag Jun 25 '13 at 14:32
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@HerrBag I completely agree. I think you hit the nail on the head with your answer (and I upvoted for it). I was more concerned with the statement (few extra feet of wire). I've seen several of these kits come with 20ft of wire and the homeowner adds another 100 feet of speaker wire and wonders why their lights are dim. –  Matt Johnson Jun 25 '13 at 19:28

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