# NCEES Power Afternoon Sample Question 505



## chicago (Oct 10, 2007)

I'm looking at this NEC code question and scratching my head.

I am using NEC 2005 and Table 430.151B referred to in the solution is no longer there.

So, obviously this must have changed since NEC 2002 publication.

Then, I find an equivalent Table 430.251B in NEC 2005.

However, there is no mention of Polyphase Design E motors at all in the Table.

Help me sort through this madness.

Question 1: Am I looking in the right place? At the risk of sounding ignorant, are Design E squirrel-cage motors not taken into account no longer?

Question 2: If this question is worded such that it is not valid for the current NEC code, then hypothetically what would you suggest a change in the wording to make it into a legitimate practice exam question?

Question 3: Also, is the additional info: 60 Hz, 52A, 0.87 lagging PF at full load all red herrings (i.e. not needed?)

Thanks


----------



## mudpuppy (Oct 10, 2007)

Don't feel bad, I wasted a lot of time on this problem when I was studying too. Design E motors were removed from the NEC in 2005. The NEC _Handbook_ has a note in it that says so. I did a little research and it sounds like they were a special type of high-efficiency motor that never really caught on. Perhaps someone else here can explain more.

I don't have a copy of the NEC or the problem to help you modify the question to make it useful. Perhaps someone else can. If I recall correctly, it was just a look-up type problem--if you could find the table you reffered to, you could pretty easily answer the question. I think you just needed to know whether to round up or down.

As for the extra info--many of the PE questions, especially the motor ones IMHO, give you extra info that is not relavent to the question. Again, I don't remember the problem exactly, but all the information you mentioned is probably unnecessary to answer the question.


----------



## chicago (Oct 10, 2007)

mudpuppy, thanks for clarifying. You're right, if it was still valid, the question is merely a lookup question. I hope there are some of these simple types on the actual exam!


----------

