Kaplan AM Sample Exam - Question 1.22

[NVRSTOP]

1.22

A commercial building with an electrical power sysytem that includes a significant number of 120-vac and 208-vac three-phase loads (four wire, WYE-connected). Computed, total load of 645 amps.

What size THHN aluminum conductor is required for the service when they are paralleled six times per phase?

a. #2, b. #1, c. #1/0, d. #2/0

Kaplan Answer = b. #1

According to NEC - 310.4 - Paralleled conductors shall be #1/0 and larger. There are a couple of exceptions, but they would not apply to this situation.

Am I missing something here or is this a Kaplan error? I couldn't find any errata information on their website.

Thanks and good luck to all on Friday!!

NVRSTOP

 

[benbo]

1.22 A commercial building with an electrical power sysytem that includes a significant number of 120-vac and 208-vac three-phase loads (four wire, WYE-connected). Computed, total load of 645 amps.

What size THHN aluminum conductor is required for the service when they are paralleled six times per phase?

a. #2, b. #1, c. #1/0, d. #2/0

Kaplan Answer = b. #1

According to NEC - 310.4 - Paralleled conductors shall be #1/0 and larger. There are a couple of exceptions, but they would not apply to this situation.

Am I missing something here or is this a Kaplan error? I couldn't find any errata information on their website.

Thanks and good luck to all on Friday!!

NVRSTOP

I am really bad at these codes, but I think I remember somebody (maybe willheldp?) mentioning that this was an error in the Kaplan test.

 

[mudpuppy]

Benbo is on the right track. At least two others have come to the same conclusion as you, NVR. See this post and this post.

 

[jdd18vm]

I think someplace else is a long thread on this. In short, you're not missing anything and are correct with your finding regarding paralleled conductors.

However, that aside, the remaining associated questions walk you through the correct processes as I recall. I didn't look at Kaplan this time around.

JD

oops didn't notice Mud linked the discussion.

 

[NVRSTOP]

Thanks Benbo, Mudpuppy, & JD for the info and links to previous discussions. I probably should have searched for this topic before posting. Trying to cover as much as possible, as many times as possible before the exam, but haven't used the Kaplan material too much.

Thanks again & Good Luck to all on Friday!

NVRSTOP

 

[wilheldp_PE]

I am really bad at these codes, but I think I remember somebody (maybe willheldp?) mentioning that this was an error in the Kaplan test.

Nope...I really shouldn't be giving advice on NEC related problems seeing as how I will be taking the Computers afternoon session.