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Thread: test questions

  1. #1
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    test questions

    Just passed md contractors exam & couple of questions are still stumping me:
    1.What % of secondary current is protected by primary ocpd?(I forget trx setup or %s)
    2. Whats minimum times current is a fuse allowed to protect >600v service? Smallest choice was 1.
    3. What is voltage to ground for b phase on 240v ungrounded(?) delta? I chose 208, but what's reference ground, primary ground?
    ty

  2. #2
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    4. What's smallest size conductor allowed in parallel? I chose 1/0, but couldn't also be 6awg for gec?

    Sent from my SAMSUNG-SM-G891A using Tapatalk

  3. #3
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    Quote Originally Posted by gunpowder View Post
    Just passed md contractors exam & couple of questions are still stumping me:
    1.What % of secondary current is protected by primary ocpd?(I forget trx setup or %s)
    2. Whats minimum times current is a fuse allowed to protect >600v service? Smallest choice was 1.
    3. What is voltage to ground for b phase on 240v ungrounded(?) delta? I chose 208, but what's reference ground, primary ground?
    ty
    Quote Originally Posted by gunpowder View Post
    4. What's smallest size conductor allowed in parallel? I chose 1/0, but couldn't also be 6awg for gec?

    Sent from my SAMSUNG-SM-G891A using Tapatalk
    1. Not sure the actual question here, but thinking you are looking for primary to secondary ratio to be involved here?
    2.
    3. If it is an ungrounded system the voltage to ground can be fairly unpredictible as there is no ground reference until there is a ground fault on something.
    4. 1/0 is the correct general rule answer. You can't parallel GEC's or EGC's for the purpose of effectively making a larger capacity conductor out of smaller conductors. You still end up with parallel paths in many instances though.

  4. #4
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    1) Look at 450.3
    2) Not sure the way the question is written.
    3) Ungrounded=0
    4) Forget GEC's, #1/0 look at 310.10(H).
    Rob

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    All responses based on the 2014 NEC unless otherwise noted

  5. #5
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    Quote Originally Posted by infinity View Post
    1) Look at 450.3
    2) Not sure the way the question is written.
    3) Ungrounded=0
    4) Forget GEC's, #1/0 look at 310.10(H).
    Your #3 answer vs my #3 answer is all about capacitive effects, otherwise the theoretical answer is 0, if there are no ground faults in the system.

  6. #6
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    Quote Originally Posted by kwired View Post
    Your #3 answer vs my #3 answer is all about capacitive effects, otherwise the theoretical answer is 0, if there are no ground faults in the system.
    I would say the answer is "undefined". If you put a meter from the B phase to ground, you probably won't see 0V, but rather some nonsense number. If "none of the above" is a choice, then it's the right one no matter what the other choices are, IMO.

  7. #7
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    Quote Originally Posted by ggunn View Post
    I would say the answer is "undefined". If you put a meter from the B phase to ground, you probably won't see 0V, but rather some nonsense number. If "none of the above" is a choice, then it's the right one no matter what the other choices are, IMO.
    I agree.

  8. #8
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    Quote Originally Posted by kwired View Post
    I agree.
    Some test questions are designed to make you burn up test time trying to do calculations if you do not understand the underlying principle that makes the calculations unnecessary or futile. Sneaky.

    In a multiple choice test the first thing you should do on every question is to see which of the answers you can rule out without doing much if any calculation.

  9. #9
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    Quote Originally Posted by ggunn View Post
    Some test questions are designed to make you burn up test time trying to do calculations if you do not understand the underlying principle that makes the calculations unnecessary or futile. Sneaky.

    In a multiple choice test the first thing you should do on every question is to see which of the answers you can rule out without doing much if any calculation.
    Also agree.

  10. #10
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    Quote Originally Posted by ggunn View Post
    I would say the answer is "undefined". If you put a meter from the B phase to ground, you probably won't see 0V, but rather some nonsense number. If "none of the above" is a choice, then it's the right one no matter what the other choices are, IMO.
    I would guess that the answer undefined wasn't on the test so you would need to look for the theoretical answer which should be 0 since it says that it's ungrounded.
    Rob

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    All responses based on the 2014 NEC unless otherwise noted

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