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Joined: Feb 2004
Posts: 9
S
srinika Offline OP
Junior Member
Hi All
I am preparing for the Construction & Maintenance Exam.
Please give me the answers and the section where applicable

1. What is the difference between Table 17 & Table 18?
2. When finding the no. of conductors in a PVC conduit, should v consider the bonding conductor as well?
3. In a calculation if v get the fuse size as 180A, when using table 13, what fuse v should select? (200A or 175A). In codebook is there any rule saying that v should select the one lower than, what v found in table 13?
4. Is there a specific max. ground fault current permitted in a patient care area (is it same as 6mA ?)
5. In an AC system if frequency is doubled, what will happen to the RMS value of Voltage ?
6. Is Jacketed means Sheathed ? In Table 6, there is a division as jacketed /unjacketed. In Table 8 there is a division as lead sheathed / non lead sheathed. How to determine from the given data, whether the cable is having the sheath / jacket ?
7.When there r more than 4 conductors in free air, what table(s) should v consider?
Is it Table 2 only or use table 1 / table 5C
or table 2 / table 5C ?
8. How do v determine the size of
Service Neutral

Thanx in advance

Joined: Oct 2003
Posts: 147
C
Member
Srinka: Eight questions is alot (some of the answers to the questions are rather involved) for a single thread. Your first question is very interesting. Table 17 will give you the size of the conductor that runs from the ground rods to the neutral in the service, and grounds the electrical system (it will also give you the size of an X0 conductor to ground an electrical system feed by a transformer in a building). I have never seen an exam question on Table 18, and have never received a good explanation on what it is for. As near as I can figure Table 18 would be used on a system that does not have a neutral and the electrical system is not grounded (check 10-812 and 10-106(1)). The conductor for Table 18 would go from the ground rods to the ground buss, but would not go to the neutral because there is no neutral.

[This message has been edited by crash (edited 02-24-2004).]

Joined: Feb 2004
Posts: 9
S
srinika Offline OP
Junior Member
Hi Crash!
Thanx for the Ans.
Should I post 1 by 1 ?

I checked the forum for the other Qs, but couldn't find answers for those.

I have so many other Qs as well.

Please help me to find solutions to these Qs

Regards
Srinika

Joined: Jan 2003
Posts: 73
C
Member
srinika

Just a suggestion!

DO not try to memorize the code book!
Learn how to use it.

The questions related to "Tables" > At the top of the tables are Rule #'s those numbers relate to that specific table. If you look at the rules related to that table it will lead you it's proper use (most of the time).
One thing that will help speed up that process however is knowing what is covered in "Sections in the Code book".
example: Section 10 = Grounding, section 12 Installation of electrical equipment, and so forth.

Also the index at the back of this book is very helpfull as long as you know the definitions which is "Section 0".

The only thing that the code book does not really cover is the "theory of electricity", however if you know the "theory", you might be surprised to find the most of the code book is based on those "theories and what if's".

Good Luck

Joined: Oct 2003
Posts: 147
C
Member
On a similar note to what Cdn Electrician said. Your second question has to do with conduit fill and bonding conductors. If you go to one of the tables that have to do with conduit fill (Table 6,8,9 and 10), there is a code rule at the top, the code rule answers the question but is not very clear on that issue. But you will notice that the code rule has a reference to Appendix B, The third paragraph in that section of appendix B answeres your question very clearly. It even tells you what to do if the Ground wire is uninsultated.

[This message has been edited by crash (edited 02-25-2004).]

[This message has been edited by crash (edited 02-25-2004).]

Joined: Feb 2004
Posts: 9
S
srinika Offline OP
Junior Member
Thanx a lot.
Its in Appendix B 12-1014

Since I'm a bit new to this, it was a bit harder for me to locate.

Thanx again.
Srinika

Joined: Oct 2003
Posts: 147
C
Member
The only thing I can find on patient care areas applies only to washrooms. Rule 24-106(3)&(4). If its not in a washroom or bathroom then I am not aware of any other ground fault requirements.


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