Residential Load Calc

[dezwitinc]

I am currently involved in a brooha (battle) with an inspector in a small Florida town who will not accept my load calculations for a generator installation.
Here is the scenario:
He is insisting that 220.30(C)(6) does not apply. His contention is that
424.3(B) (2002 NEC) or 424.3(B) (2005 NEC) requires heating to be included at 125% in the load calculation because it is considered a continuous load and that 220.30(C)(6) is not a valid calculation.
I have tried to explain that this article only refers to branch circuit sizing but he will not buy into it.
His reply is to quote an NFPA opinion that says heat should always be figured at 125%.
Has anyone else ever heard this argument and if so, how did you deal with it?
In the end, I will probably end up shedding the heat load but I would like to make my stand and not have to go back to the customer for additional costs.

 

[bphgravity]

It's not a good idea nor really professional to directly mention the individual your are having issues with unless that person is here to defend their position. I happen to personally know the person you are speaking of and feel you should edit his identity out of your post.

 

[dezwitinc]

Thank you Bryan, I will.

 

[haskindm]

If you want to fight this, you will need to find out who the inspector answers to. Hopefully they will have some idea how to interpret the code and will over-rule the inspector. Nothing requires you to calculate heat at 125% for service load, just the branch circuit. Most thermostatically controlled devices are not considered continuous loads, the exception being water heaters. Would he also require that you calculate the range at 125% or will he accept 220.55 for that? Figuring the range at 125% makes as much since as figuring the heat at 125%. What type of heat is it? How many units?

 

[dahualin]

dezwitinc-

If you have 2005 NEC hand book, please go to Annex D examples D1 (b) one-Family Dwelling with two AC units. It clearly shows the AC load is not calculated with 125% factor. Since the bigger AC unit is the biggest motor, its 25% load is added by that category. You can show the example to the inspector. I believe it will help a little bit.

I have a Stallcup's Electrical Design Book that shows same idea of Commercial Calculations on compressor loads as NEC hand book do. No AC units (compressor loads) need 125% factor unless it is the largest motor.

David

 

[bphgravity]

Thanks for your PM, dez...

I would prefer to hold comment at this time on this issue as I have recently learned that the Florida Building Commission and the Department of Community Affairs is currently looking into this very issue. There is significant legislation in the works regarding generator installations here in Florida. A special committee has been formed to investigate the issue.

That being said, I agree with most of the comments and I do agree with you. 25% is not required to be added to the A/C or heat loads when figured using either the standard or optional method in Article 220.

Our department has written a document on generator installations that closely mirrors one produced by Tarry Baker of Broward County whom sits on CMP 13 that covers Article 702. By the way, he is on the committee mentioned above...