another question

[cherokeerm7]

hey guys,
another couple of question i had was in my exam prep book on the sample test, i would appreciate the help.

1. why does the NEC require wire in the same raceway?
i came up with to reduce heat as per 300.20(A) what do yall think

2. why does the NEC require metal conduit to be grounded?
a.to make sure of equipment grounding
b. to reduce static electricity
c. to ensure electrical continuity
d to reduce resistance
i have c due to 250.90

3. Do you need a light switch in an attic or crawl space that is not used for storage?
i say no but it does not directly say in the NEC 210.70(A)(3)

4. when can nonmetallic sheathed cable be used for return air plenums?
I cant find anything the closest i have is 300.22

last one
5. why does a battery need good ventilation when it is being charged in a room?
i have accumulation of explosive mixture per 480.9(A)


info would be greatly appreciated guys

 

[charlie b]

Re: another question

I would change answer (1) to say ?avoid heating,? as opposed to your phrase, ?reduce heat.? But otherwise I agree.

For item (2), I would have selected answer (a). If the question allowed, then I might have picked (a) and (c), but to my view (a) is the better answer.

For item (3), I agree with your answer of ?no.? 210.70(A)(3) only requires a switched light if the area is used for storage or contains equipment requiring servicing. Lacking these two items, the space would not require a switched light.

For item (4), the key issue is that a ?return air plenum? counts as being ?used for environmental air.? Therefore, 300.22 says that NM is not allowed (i.e., NM is not on the list of what is allowed).

For item (5), I agree with your answer.

 

[cherokeerm7]

Re: another question

thank you very much you help really helps out alot

 

[cherokeerm7]

Re: another question

one more

SE cable is used to feed subpanel, What should a journeyman electrician do to the cable

a.check if the cable has 5 conductors
b.check if all conductors are insulated
c.put the se cable in rigid conduit
d.put se cable in sch 40 pvc

i know the question isnt worded that good but its all i can remember of it

 

[jimwalker]

Re: another question

#3 is a bit gray.We are forced here to put a light and switch in the attic even when the AC unit is not in attic and trusses are not rated for storage unless stamped to do so .

 

[iwire]

Re: another question

Jim it is not a gray area to the NEC only to your inspectors.

 

[peter]

Re: another question

cherokee,
Concerning your first post, question #2:
2. why does the NEC require metal conduit to be grounded?
a.to make sure of equipment grounding
b. to reduce static electricity
c. to ensure electrical continuity
d. to reduce resistance
I have c due to 250.90

I looked at 250-90 and it seems to support both a and c. The test makers probably have decided one or the other is correct and you have to play some mindgames with them. I think the test makers should post all of their proposed questions on this forum so us exoerts can give a qualified opinion as to whether the question makes sense or not.
~Peter

 

[jimwalker]

Re: another question

I think somewhere i read that these tests are designed to flunk 90% and if any question is answered correctly by more than 50% they deleet it

 

[stars13bars2]

Re: another question

When we run green insulated ground conductors in metal conduit,as I know a lot of us do, it eliminates the need to use the conduit as the equipment ground. Therefore I would choose "C" as the correct answer.
The people who wrote the test had a group of code experts who helped them write the questions like these. Someone without a good knowledge of the code would not be able to come up with so many ambiguous questions. You have to systematically eliminate the wrong answers, and under the time constraints of the test, this becomes very difficult. There are also some questions on the test about materials and practices that have not been made or used in thirty to fifty years. The test writers didn't come up with these on their own. I feel that the test should contain more straightforward questions. I do not think that making it as difficult as they want would be a problem without the tricky stuff. Sorry for the digression.

 

[ryan_618]

Re: another question

I think #4 would be dwelling units when the cable passes perpindicular through the stud/joist space. I think this is in 300.22, exception, but I'm not positive.

 

[cherokeerm7]

Re: another question

this is not making me feel very good about the test guys, im worried about the one question above about metal conduit grounding, cause i can see where a and c are correct, it seems as if you answer either one they mark it wrong, just a thought.

 

[jimwalker]

Re: another question

Why would your boss not exstend the time if he sees you are trying to pass the test ?Was this a requirement before you took the job ?

 

[jonkja]

Re: another question

About the question on the se cable I think I would put c on it rigid metal conduit after reading 230 50 A but there is talking about service cable, the other a b and d just do not make any sense to me but I am not sure about this
jon