Hey guys, me again. Just took my electrical exam and again fail by one point. sucks. I got a few question that was tricky for me and was wondering if you guys could tell me if I did it right or not. Also keep in mind that all the information i have might not be right due to just memorizing it from the test.
1) you have a 120/240v 3 phase 4 wire and they wanted to know where a 20 amp breaker can be install in? 2 answer
a) a phase A-B line to line
b) a phase A-C line to line
c) a phases A-C multi wire
e) a phase C-B line to line
f) a phase A-B-C line to line
I was not sure what the answer was so I guess c and f. I understand there is a high leg on B phase but the answer are line to line? To me, I thought they all work. can some one help me out
Question #2
A B
480v 10amps --------- ------------ 23 amp
I I
I I----------- N
I I
---------- ------------- ?
C
This is suppose to be a diagram on a transformer. primary 480v secondary 120/240v
Wanted to know what the Nuetral would read when you put a ampmeter on it?
a)3
b)4
c)5
e)6
f)7
What I did was A 480v x 10amp= 4800va
B 120v x 23amps= 2760va 4800va - 2670 va = 2040va for C phase. Then 2040/120v = 17amp
So to find the Neutral, I did 23amp-17amps= 6 amp ( answer is E right?)
Question # 3
How can you change class h fuses renewal? 3x answer
a) interrupting rating 10,000
b)where maintenance keeps records of fuse replacement
c)have to have to right testing equipment
e)replacement only
f)no evidence of over fusing or tampering
240.60 (d) I put down for answer B,E,F. Im thinking it was A,E,F. I did not fing anything that say it has to be 10,000 amps or maintenance records. What do you guys think?
Question #4
Have a 3 phase squirrel cage motor at 480v 60 hp. Wanted to know what the maximun rating dual element fuse for branch circuit short circuit?
a)125
b)150
c)175
d)200
e)225
60hp=77amps from table430.250
77 x 1.75 ( from T430.52) = 134.75 amps
77 x 2.25 ( expection no 2) = 173.25 amps
I was confuse for what is the maximum. I would think the 225% would be max . I put down B for my answer at 150 amps. 134.75amps next larger size is 150 amps. 173.25 is maximum and you cant upsize so I went back down to 150. Which one is the right one to do when I say maximum?
Question #5
Wanted to know branch circuit short circuit protection. namplate on conderser reads 20.5 amps for compressor motor and fan motor is 1.5 amps. conductor rated at 27 amps, maxiumum breaker at 40 and max hvac breaker at 40 amps.
a)20
b)30
c)40
d)45
440.22(a)
here we go again with maximums? Okay so this is what I did 20.5 x 2.25 + 1.5= 47.625. I put down 45 amps as my answer. If I was to use 175% then I would get 37.375 with a 40amp breaker. What do I do when they say maximum? 225% will be the max but only when it keeps blowing fuse or circuit breaker but the question doesn't say that.
Question #6
Your going to replace a receptacle in an industrial application and it doesn't have a equipment ground. How can you change this? 2x answer
a) a non grounding type receptacle shall be permitted
b)GFCI receptacle mark "no ground"
c)a grounding type recpetacle where protected by GFI from a receptacle or circuit breaker
406.4(d)2
I put down B and C. I was not sure with this but the code says you can only replace non grounding type receptacle with non grounding type receptacles. The question didn't state what type of receptacle it was. tricky?
Question #7
Why do we put a capacitor in front of a induction motor? These are the only answer I remember
1) improves power factor
2) decrease power factor
3) runs motor at constance speed
I put down improves power factor as a guess.
Question #8
In general, where can the disconnect be located for motor control? 2x answer
1)located in sight from controller location
2) be able to lock in open position out of sight
3) less than 50 ft from the controller
430.102(a)
I put down 1 and 3. When they say in general, do I include exceptions? answer #2 was in the expection but over 600v . What do you guys think......
This is it for right now. Still pretty devasted because I fail by one point the last two test. next time.....
1) you have a 120/240v 3 phase 4 wire and they wanted to know where a 20 amp breaker can be install in? 2 answer
a) a phase A-B line to line
b) a phase A-C line to line
c) a phases A-C multi wire
e) a phase C-B line to line
f) a phase A-B-C line to line
I was not sure what the answer was so I guess c and f. I understand there is a high leg on B phase but the answer are line to line? To me, I thought they all work. can some one help me out
Question #2
A B
480v 10amps --------- ------------ 23 amp
I I
I I----------- N
I I
---------- ------------- ?
C
This is suppose to be a diagram on a transformer. primary 480v secondary 120/240v
Wanted to know what the Nuetral would read when you put a ampmeter on it?
a)3
b)4
c)5
e)6
f)7
What I did was A 480v x 10amp= 4800va
B 120v x 23amps= 2760va 4800va - 2670 va = 2040va for C phase. Then 2040/120v = 17amp
So to find the Neutral, I did 23amp-17amps= 6 amp ( answer is E right?)
Question # 3
How can you change class h fuses renewal? 3x answer
a) interrupting rating 10,000
b)where maintenance keeps records of fuse replacement
c)have to have to right testing equipment
e)replacement only
f)no evidence of over fusing or tampering
240.60 (d) I put down for answer B,E,F. Im thinking it was A,E,F. I did not fing anything that say it has to be 10,000 amps or maintenance records. What do you guys think?
Question #4
Have a 3 phase squirrel cage motor at 480v 60 hp. Wanted to know what the maximun rating dual element fuse for branch circuit short circuit?
a)125
b)150
c)175
d)200
e)225
60hp=77amps from table430.250
77 x 1.75 ( from T430.52) = 134.75 amps
77 x 2.25 ( expection no 2) = 173.25 amps
I was confuse for what is the maximum. I would think the 225% would be max . I put down B for my answer at 150 amps. 134.75amps next larger size is 150 amps. 173.25 is maximum and you cant upsize so I went back down to 150. Which one is the right one to do when I say maximum?
Question #5
Wanted to know branch circuit short circuit protection. namplate on conderser reads 20.5 amps for compressor motor and fan motor is 1.5 amps. conductor rated at 27 amps, maxiumum breaker at 40 and max hvac breaker at 40 amps.
a)20
b)30
c)40
d)45
440.22(a)
here we go again with maximums? Okay so this is what I did 20.5 x 2.25 + 1.5= 47.625. I put down 45 amps as my answer. If I was to use 175% then I would get 37.375 with a 40amp breaker. What do I do when they say maximum? 225% will be the max but only when it keeps blowing fuse or circuit breaker but the question doesn't say that.
Question #6
Your going to replace a receptacle in an industrial application and it doesn't have a equipment ground. How can you change this? 2x answer
a) a non grounding type receptacle shall be permitted
b)GFCI receptacle mark "no ground"
c)a grounding type recpetacle where protected by GFI from a receptacle or circuit breaker
406.4(d)2
I put down B and C. I was not sure with this but the code says you can only replace non grounding type receptacle with non grounding type receptacles. The question didn't state what type of receptacle it was. tricky?
Question #7
Why do we put a capacitor in front of a induction motor? These are the only answer I remember
1) improves power factor
2) decrease power factor
3) runs motor at constance speed
I put down improves power factor as a guess.
Question #8
In general, where can the disconnect be located for motor control? 2x answer
1)located in sight from controller location
2) be able to lock in open position out of sight
3) less than 50 ft from the controller
430.102(a)
I put down 1 and 3. When they say in general, do I include exceptions? answer #2 was in the expection but over 600v . What do you guys think......
This is it for right now. Still pretty devasted because I fail by one point the last two test. next time.....
