Test Ques.

[Flight987]

This from a pratice test for AJ. Here is the Ques.. What minimum size feeder conductors(thhn) are require to suppy five,230volt continuous duty ,three-phase, 5-HP moter's, which have F.L.C. of 15.2 Amp. each.
This is a closed book part of the Exam.
I did the math, check me if I am right, (15.2x5=76.) or (15.2x1.25=19, for the largest moter) = 19+15.2+
15.2 +15.2 +15.2=69.8, With that in mind, there is not a highist moter to do the Cal.. Now it seem's to me that
there are playing a mind game with this Ques.. I can go to 310.15(B) That's how Minnesota states there code,
tables are not a reference. I know we end up at 310.16, but as I said it is closed book.
So on the answer, from the key #4 awg. Anyone have help

 

[Dennis Alwon]

Check your math. First you did 15.2*5= 76, then you took 125% of the largest motor and got a smaller number. 15.2* 1.25 = 19 so add the difference 3.8 to the 76. This would be 79.8 amps.

OR

(15.2 * 4) + (1.25 * 15.2)= 79.8-- Edit to add --I guess that was a typo

 

[augie47]

I think you need to check your math....
79.8


opps Dennis saw it 1st

In real life where the rating of the terminations would be 75? a #4 would be fine, but based on 110.14, with your current less than 100 amps, I'm suprised the didn't say a #3.

 

[Flight987]

Okay, My math

Okay, My math

Ok, My math Problem. Thank's, This is a closed book test. Good luck on that Amp.

 

[Dennis Alwon]

Ok, My math Problem. Thank's, This is a closed book test. Good luck on that Amp.

I doubt they will ask you to memorize the table of ampacities. They may give the table as a handout. Good luck

 

[jumper]

I doubt they will ask you to memorize the table of ampacities. They may give the table as a handout. Good luck

I would hope so, I doubt that I know more than few items off any of the tables.

 

[jumper]

Curt, I always like to maximize test questions, more bang for buck.

If you use inverse time (standard) breakers, what is the maximum size OCPD you can use to protect the feeder?

See 430.62 to start.

 

[Flight987]

New test Ques.

New test Ques.

If 3 20 ampere, 120 volt duplex Rec. are installed in the laundry room (or area) of a single family dwelling unit, along with one 20 amp, 120volt single-receptacle (which will supply the wash machine), the Code permits them all to be supplied by the same 20 amp, 120 volt, laundry branch circuit. Key Answ. true, Ref. 210.11(C) 2.
I said false. When typeing this, the only thing that makes sence to me is a multy-wire branch cicuirt.
Can you do a Mult. wire branch circuit on this one. I looked at the Ref. also.

 

[97catintenn]

True.

210.11(C)
(2) Laundry Branch Circuits. In addition to the number
of branch circuits required by other parts of this section, at
least one additional 20-ampere branch circuit shall be provided
to supply the laundry receptacle outlet(s) required by
210.52(F). This circuit shall have no other outlets.

That means all of them. The last line, means that it cannot supply outlets in other areas. Just the laundry room. Good question. I thought it was false too.

 

[Flight987]

So let's

So let's

So let's look at it closer. Can you explain the wording, that I don't see? Is this a Mult. wire branch Cirt.
I am glad to see I am not the only one out there, that doesn't get right all the time. God didn't create
anyone prefect. Please respond

 

[Dennis Alwon]

The section states that one 20 amp circuit shall supply the laundry room receptacles. Receptacles is plural meaning more than one. This circuit cannot leave the room nor can any lights or anything else be hook to them- just the recep. in the room. This does not mean you have to do it that way. I often run a circuit for the washer and then one for the other laundry receptacles-- that is my preference not code.