Residential panel branch circuit load calcs

[littleredbirds]

Newb here... I am about to start filling out the panel schedule attached, but I have questions....

1. What do you make of the derate per chapter 9 statement at the bottom left of thd table? I looked in chapter 9 of nec 2014 and it seems they might be mistaken in their reference. Is the deration intended for the total or individual branch curcuits?

2. I am somewhat familiar with running load calcs to size for a house using the squarefootage of a home, but am a bit confused when it comes to determining the exact load of individual branch circuits. For receptacle circuits I figure I can use the 180VA rule per receptacle, for lighting I can use actual fixture ratings, and for motors I can use nameplate ratings and nec motor tables, but im not sure if I should include toasters, microwaves, ceiling fans, etc. Am I following the right approach here? Since they are asking for branch circuit loads I sould think they want actual loads installed/used in the house and not the pre-construction load calcs used to size the panel and circuits. If anyone knows of a guide, section in code, or is familisr with running branch circuit load calcs post construction, can you please help?

Thank you.

 

[littleredbirds]

Bump... should this be in under a different topic?

 

[ActionDave]

The lighting load is covered by the 3VA per sq ft and the microwave and toaster is covered by the 1500VA assigned to each small appliance branch circuit.

Take a look at the annex in the back of the code book for standard and optional load calcs, it's very helpful.

 

[iwire]

Take a look at the annex in the back of the code book for standard and optional load calcs, it's very helpful.

For sure, I use the annex when I have to do calculations.

 

[littleredbirds]

Thanks guys. I see annex d is helpful for feeder and service sizing but I'm still not sure how to translate that to branch circuit by branch circuit or breaker by breaker loads. Thanks again.

 

[ActionDave]

What is this for?

 

[Smart $]

Thanks guys. I see annex d is helpful for feeder and service sizing but I'm still not sure how to translate that to branch circuit by branch circuit or breaker by breaker loads. Thanks again.

Review 210.11.

Then keep in mind your actual connected lighting load cannot exceed 80% of the circuit rating (12 for 15A, 16 for 20A).

You can use 180VA if you want... but I'd recommend you weight each one by what you think may get plugged into it. Note this is regarding general use receptacles. Small appliance branch circuits are another puppy and there's plenty of posts on that matter....

It's the combination lighting and receptacle circuits that are a bear... so the best recommendation is to just proportion them out, and maybe throw in a little by the gut feeling in. :angel:

 

[littleredbirds]

@ActionDave - This is for a homeowner solar permit. Familiar with solar code, but not so strong with the resi code. Plus it just seems weird to have to list all the loads connected to the panel. I dont remember every having to do this on commercial systems. It was always about the panel/bus rating and the feedback breaker rating.

@Smart $ - THanks for the tip. I started looking at that last night. Seems there's no straight rule for this and I need to do what makes sense based on the feeder/service load calcs.