Dwelling unit load calculations - confused by example in exam prep book (2020)

C

ChesterDawg

Member
Location
CA
Hi,
I'm going through the 2020 version of the exam prep book and I'm confused by the first example question for a dwelling unit load calculation.

The calculations end up coming up with 322 amps, but the answer says to use a 400 amp disconnect.

350 amps is listed as a standard breaker size in 240.6(a) and also listed in 310.12 as a service size.

What am I missing?

thanks

https://imgur.com/a/I7cBxKD
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I think the answer may be based on using a fusible disconnect, but those are rare now days. You are correct that a 350 amp enclosed breaker could be used for this service as long as it is listed as suitable for use as service equipment.
 
Thank you. I felt like I was missing some final step in the load calculation, but I couldn't find what it was in the code book.

Feeling better about just chalking it up to an error/outdated information in the exam prep book now.
 
ChesterDawg said:
Thank you. I felt like I was missing some final step in the load calculation, but I couldn't find what it was in the code book.

Feeling better about just chalking it up to an error/outdated information in the exam prep book now.
Click to expand...
Out dated books will do this. I know all about this
 
You could write to "content" "@mikeholt.com" and report the issue with the exam prep material.
There are also a much wider array of fuses out there, compared to breakers: a fused disconnect can be more finely tailored.
 
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