2005 water heater issues

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ryan_618

ryan_618

Senior Member
Location
Salt Lake City, Utah
422.13 is driving me crazy.

It now says that water heaters are a continuous load. In the 2002, you had to provide 125% for the branch circuit conductors, but nowhere else.

So the question is, how does this relate to article 220? If I have dwelling unit with 4 appliances, I can apply a 75% demand factor to them...well, this makes no sense for something that is a continuous load! I've looked deeper into it, and I have noticed that 422.13 is not included in table 220.3. This is what I am comin up with:

1) The branch circuit must be sized at 125%, because of 210.19.

2) The feeder circuit must also be 125%, because of 215.2.

3) The service conductors must also be 125%, because of 230.42.

4) This new change in 422 does'nt not change anything in article 220, because it is not in table 220.3.

What do you guys think?


BTW: Sorry its been so long since I've posted :(

[ February 11, 2005, 12:33 PM: Message edited by: ryan_618 ]
 
Re: 2005 water heater issues

The way I see it: fixed appliance loads, such as water heaters, dishwashers, water pumps, etc., shall added together and be subject to a demand factor according to 220.17 in order to compute the element of the service. However, the branch-circuit element shall be computed and sized according to other section in NEC. For example, water heater at 125% per 422.13, dishwasher at 100% per 422.10(A) and 422.62 and so on, and this includes conductors and OCPD's feeding & protecting branch-circuit.
 
Re: 2005 water heater issues

Since none of the example calculations in Annex D increase the water heater loads by 25%, I feel it does not need to be considered when using any of the methods for sizing the service or feeder by Article 220.
 
Re: 2005 water heater issues

There are two different CMP's involved. There's supposed to be cross checking to prevent changes from "accidently" impacting something that wasn't intended. This may have gotten by the process. But the rule of the code says to follow 220.

Edit: I had to correct some pretty poor grammar.

[ February 11, 2005, 04:14 PM: Message edited by: physis ]
 
Re: 2005 water heater issues

Maybe I misunderstand the question.

Aren't you asking how this effects the application of 220?
 
Re: 2005 water heater issues

I'm sorry Sam, I may have misunderstood your original post.

Do you agree that the change to 422.13 does nothing to the application of article 220?
 
Re: 2005 water heater issues

Yes. :)

Edit: And if you're thinking "what the, does the rule of the code mean". You're right, it doesn't mean anything. :D

[ February 11, 2005, 06:29 PM: Message edited by: physis ]
 
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