Max No of devices in a 14/2 wire

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Old 11-16-07, 05:31 PM
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Max No of devices in a 14/2 wire

In a book by Roger German, it states "Code requires maximum 10 devices on a 14/2 wire".

I am wiring 10 recessed lights that are max 50W in the entertainment area. I am also planning to add 4 more lights to this circuit for the walk way. Will this violate code? My point is the total watts on this line with these 14 devices would not exceed 700W. This is well within the limits of 14g wire ie (15 x 120 = 1800W) ???

Any opinion?

Thanks in advance
 
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Old 11-16-07, 06:08 PM
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There is no max limit in the US. I believe Canada has a max limit of 10 I believe, and that is for receptacles.
 
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Old 11-16-07, 06:24 PM
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Rakki, what the book may have been talking about was the 180VA per receptacle load calculation. That is only for receptacles and doesn't even apply to dwellings at all.

As for your recessed lights which are max 50W fixtures, your calculation and conclusion were right on. You are fine. Now some folks will tell you to multiply that 1800W by 80%, leaving you with only 1440W, and that's not a bad idea, but is NOT required by code for your house. Lighting in a dwelling is considered a noncontinuous load even if someone could choose to leave it on all day.
 
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Old 11-16-07, 06:27 PM
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Thanks again guys for the immediate reply. It helps a lot.
 
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Old 11-16-07, 06:36 PM
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The Canadian limit is 12 and it does not apply to 100% lighting loads.
 
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Old 11-16-07, 08:47 PM
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Originally Posted by core View Post
Now some folks will tell you to multiply that 1800W by 80%, leaving you with only 1440W, and that's not a bad idea, but is NOT required by code for your house. Lighting in a dwelling is considered a noncontinuous load even if someone could choose to leave it on all day.
Could you point me to the part of the Code that shows this exception? All I can find is that the ampacity must be 125% of any load that can run for more than three hours... leaving you with 1440 watts in this case.
 
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Old 11-16-07, 08:58 PM
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mukansamonkey,
Let me know when you find it.
I'll be waiting.
 
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Old 11-17-07, 01:24 AM
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Originally Posted by mukansamonkey View Post
Could you point me to the part of the Code that shows this exception? All I can find is that the ampacity must be 125% of any load that can run for more than three hours.
mukansamonkey, I can't point you to an exception in the code because there isn't one.

Your definition was close, the exact verbage is: A load where the maximum current is expected to continue for 3 hours or more. There is a huge difference between can and expected.

The code says very little about precisely what is continuous and what is not. But in general in a dwelling there are very very few things that would be considered a continuous load. Commercial is a different story. Now if you have a photocell controlled light in a residential setting I'd personally call that continuous, but I'll betcha some would not.

The closest thing to a written "exception" that you wanted that I could find is as follows:

In the Handbook is an interpretation/explanation under 210.20(A). It is a diagram of 4 4A lights connected on a 20A branch circuit. The caption reads:

Exhibit 210.22: A continuous load (store lighting) calculated at 125 percent to determine the ampacity of the conductor and the branch-circuit size.

Now if the word "store" wasn't crucial here they wouldn't have included it. You know how these lawyerly types are. I agree, it's not much to go on, but it does support what I said.

*shrug* I'd be willing to listen to other interpretations though.

dezwit: Not sure what that meant... who's side are you on? *grin*
 
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Old 11-17-07, 04:35 PM
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I am on the side of truth, justice, and the National Electrical Code way.
I will agree that in a residential setting it is not clear as to the rating of the circuit.
Table 220.42 requires the first 3000 VA to be taken at 100% when calculating feeder size but leaves alot of room for figures.
Interesting.
I have never really considered this issue as the Code does not address it specifically.
I am going to investigate.
 
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