Code Ques.

[Gac66610]

:huh::?:blink:

I know... right,
dude ...... DEcafe:lol:

got a lot going through that brain of yours it can be overwhelming, take a breath, go to the movies, take a date to dinner!

 

[kwired]

A MLO, lighting and appliance panelboard, rated 100 amperes, is permitted by the NEC to be installed
on, and protected by a 200 ampere feeder. Key Answ. False, Ref.408.36
Thank's guy's for the help! I just get so caught up in trying to understand this.
I have had no Exp. on a MLO. I confess I don't know what it stand's for?
I have read 408.30 through 408.37. I understand the 408.34 (A) and (B).
Went to index and that bring's me to 408.35,408.36. Went enternet and typed in MLO
Panelboard's and Mike's page came up on one site. I see I am not alone on this.

Someone told you what MLO stands for, now go back to 408.36 again. The panelboard must be protected by an overcurrent device equal or less than the rating of the panelboard. The question is proposing to protect a 100 amp panel with no main with the overcurrent device on the 200 amp feeder - not permitted - answer to question - false.

 

[Flight987]

Code Ques.

What is the primary current and the secondary neutral current on the trransformer shown below when the secondary currents on phase A and phase B are 22 and 38 Amp's. respectively? Answ. Key Ip-15A,
In-16A.
It is a 480 to 120 Trans. I don't know how to draw on site. Do I have to draw for you?
I must confess that my family has a medical thing happining now and I am feeling the stress of
that. It hard to think, when stress is on your mind. Thank's

 

[don_resqcapt19]

What is the primary current and the secondary neutral current on the trransformer shown below when the secondary currents on phase A and phase B are 22 and 38 Amp's. respectively? Answ. Key Ip-15A,
In-16A.
It is a 480 to 120 Trans. I don't know how to draw on site. Do I have to draw for you?
I must confess that my family has a medical thing happining now and I am feeling the stress of
that. It hard to think, when stress is on your mind. Thank's

It would have to be a single phase 480 to 120/240 transformer to match the question and the answers.

 

[Flight987]

Yes You

Yes You

Yes, You are correct. Sorry that I didn't say that. Do you need me to try and draw it?
I think it is a simple math thing, that I am not seeing. I did so well on Mike's work
book on Trans..

 

[don_resqcapt19]

Yes, You are correct. Sorry that I didn't say that. Do you need me to try and draw it?
I think it is a simple math thing, that I am not seeing. I did so well on Mike's work
book on Trans..

I don't need you to draw it. It is a simple math thing. Tell us how you think it should be solved. You do have to think a bit about the the primary current. The secondary neutral current just like the neutral current on any 120/240 volt multiwire circuit.

 

[jumper]

What is the primary current and the secondary neutral current on the trransformer shown below when the secondary currents on phase A and phase B are 22 and 38 Amp's. respectively? Answ. Key Ip-15A,
In-16A.
It is a 480 to 120 Trans. I don't know how to draw on site. Do I have to draw for you?
I must confess that my family has a medical thing happining now and I am feeling the stress of
that. It hard to think, when stress is on your mind. Thank's

Reverse engineer the problem.

For part 1 turn values into kVA. Make the values of kVA match.

For part 2 what is the difference between A and B. And why does this work for single phase?

 

[Flight987]

04-16-12 Ques. Tran.

04-16-12 Ques. Tran.

22+38=60Amps. Total Sec. load. 60x120 volt's= 7200 kva. Sec. kva. I am trying to find the Pri.
Current. 7200/ 480=15 Amp's. That is the correct Answ. to key sheet. As I look over Mikes work
book, do I understand, that we only use 1.732 when both the Pri. and Second. are three phase?

 

[jumper]

For any 3 phase kVA calculation, 1.732 is going to be used somewhere.

 

[Flight987]

Code Ques.

What minimum size THW Con. is permitted to be tapped from a 400 Amp. feeder when the lenght of the tap conductor does not exceed ten feet? Key Answ. #8.
Did I do this right? 240.21(B)(1)(4) Ref. Is my math right? 400/10=40 Amp.. Table 310.16,
75c, # 10 =35Amp's, # 8=50 Amp's. So a #8 is the one.
I came up with #10=35 Amp's. Would 240.4 (D) apply, say it was a 10 foot tap or less and it was a
300 Amp. feeder. 300/10=30 Amp's. Not sure how 240.4(D) applies on this one?

 

[jumper]

What minimum size THW Con. is permitted to be tapped from a 400 Amp. feeder when the lenght of the tap conductor does not exceed ten feet? Key Answ. #8.
Did I do this right? 240.21(B)(1)(4) Ref. Is my math right? 400/10=40 Amp.. Table 310.16,
75c, # 10 =35Amp's, # 8=50 Amp's. So a #8 is the one.
I came up with #10=35 Amp's. Would 240.4 (D) apply, say it was a 10 foot tap or less and it was a
300 Amp. feeder. 300/10=30 Amp's. Not sure how 240.4(D) applies on this one?

Do you mean 240.4(B) "the next size up rule"? It does not apply to taps.

240.21(B).....The provisions of
240.4(B) shall not be permitted for tap conductors.


Curt, you will get more answers if you start a new thread and not just keep posting new questions in this one.

 

[Flight987]

jumper

jumper

Did I do the Cal. right on that Tran.. I can see Second. side , but on the Pri. side if we take
7200kva/(480x1.732=831.36) or 7200kva/831.36=8.66Amp's. Did I do the Kva right?
Can't see the thread now, but it was 22 and 38, so I added them and x 120 volt's (per winding,
120/240 Second. I know on Mikes any three uses 1.732. Thank's for respond.
Have new thread up on 10' tap rule.

 

[jumper]

Did I do the Cal. right on that Tran.. I can see Second. side , but on the Pri. side if we take
7200kva/(480x1.732=831.36) or 7200kva/831.36=8.66Amp's. Did I do the Kva right?
Can't see the thread now, but it was 22 and 38, so I added them and x 120 volt's (per winding,
120/240 Second. I know on Mikes any three uses 1.732. Thank's for respond.
Have new thread up on 10' tap rule.

You have a question that is single phase. There is no 1.732 in this problem. 7200VA/480V=15 A.

You got the right answer earlier, but I cannot say that would be the way I would do it regarding the secondary. Adding the amps worked for this problem, but doing it that way in many others will not work.

 

[Strathead]

Regarding the answer's For the B to ground Ques. are:
120/240=208
100/200=173
240/480=415
300/600=519
200/400=346
I remember on a DVD that Mike said something about it.

never mind