test question on motors

T

teeg123

Member
Location
Maine
Occupation
Journeyman Electrician
good day all,
these motors and controls are killing me. I missed this question and have been working it over but can't get to the correct answer.
A 230-volt, 1 ½ horsepower single-phase AC motor is connected to a branch circuit supplied by #14 THW conductors. What is the MAXIMUM inverse time delay breaker permitted to protect this circuit?
1)40amp (correct answer)
2)30amp
3)25amp
4)20amp
ok so table 430.248 gives me 10amps
table 430.52(C)(1) tells me 250% 10*250%=25
or do you go 10*125% (for continuous duty which isn't mentioned in the question) =12.5 then 12.5*250%=31.25 which even if I round up is only a 35-amp breaker.
I have read through 430.52, they mention inverse time breakers in 430.52(c)(1)(b)(3) but I don't think that would pertain to this question.

where am I screwing this up??????

thanks very much
 
430.52(c)(1)(b)(3) does mention that if motor won't start you can increase by 400% and if that's off the original 10amps, 10*400%= 40 amps but how does one know according to question if motor won't start under normal amp rating. how would I know to use the 400% by reading that darn question or do they just assume everyone will just go there.
 
teeg123 said:
430.52(c)(1)(b)(3) does mention that if motor won't start you can increase by 400% and if that's off the original 10amps, 10*400%= 40 amps but how does one know according to question if motor won't start under normal amp rating. how would I know to use the 400% by reading that darn question or do they just assume everyone will just go there.
Click to expand...
The question states "Maximum" so you would use the greatest possible number.
 
I've noticed that a few other questions in this area leave you having to make those kinds of assumptions, but i really do appreciate everyone's help.
 
infinity said:
IMO you would never assume that on a test question unless that information was given but that seems to be what they're asking.
Click to expand...
I agree. the 250% rounded up to next standard device is the maximum. The motor has to fail to start before you can go beyond that. If they want to consider going beyond they need more information in the question indicating this condition exists. It is sort of uncommon to need to go beyond that 250%
 
They do that in Oregon test- unless you take the pre course of the guy that wrote it, all just a scam to take more money from you, it’s how this current system works.
He makes more money, state makes more money, all for badly worded questions….
🇺🇸
 
ok so when using table 430.52(C)(1) I have some review questions that require rounding up or down, I was wondering what section gives the information as to when to round down or up, I do see in 430.52(C)(1) next higher standard rating or setting shall be permitted. So, when do you know when to round down???
 
teeg123 said:
ok so when using table 430.52(C)(1) I have some review questions that require rounding up or down, I was wondering what section gives the information as to when to round down or up, I do see in 430.52(C)(1) next higher standard rating or setting shall be permitted. So, when do you know when to round down???
Click to expand...
If you were supplying more than one motor you would round down.
 
AC\DC said:
They do that in Oregon test- unless you take the pre course of the guy that wrote it, all just a scam to take more money from you, it’s how this current system works.
He makes more money, state makes more money, all for badly worded questions….
🇺🇸
Click to expand...
let me guess, no challenging their questions/answers is allowed either, because they can't possibly make mistakes.
 
I believe you can challenge it — I never did I think it took me twice to get it for the supervisor.
I just know the guy sells classes because Oregon supposed to be one of the hardest ones to pass, but it’s just the way they phrase..
 
AC\DC said:
They do that in Oregon test- unless you take the pre course of the guy that wrote it, all just a scam to take more money from you, it’s how this current system works.
He makes more money, state makes more money, all for badly worded questions….
🇺🇸
Click to expand...
I always hated it when they did “trick” questions! You could have a correct answer, but not the one they want!
 
You must log in or register to reply here.
Top