Test Question

Status
Not open for further replies.
L

luckyshadow

Senior Member
Location
Maryland
On the Master test I took this morning a factory calculation was asking about the wire size for a 50KW 208 volt 3 phase heater. Am I correct with the following calcuation:
50,000 divided by 360 (208 x 1.73) = 138.88
138.88 x 125% = 173.6
there for use 2/0 copper which is rated for 175 a
I referenced code art. 424.3 (B) 310.16

I ask because this answer was not on the answer sheet. I ran this calc. 3 times during the test plus talked with others after the test and they are coming up with the same thing.
I couldn't ask the test proctors due to they have no electrical knowledge. This causes 2 answer to be incorrect on the test. Taking a 5 point question to a 3 point. I am going to call the electrical board who gives the test on Monday ,but I wanted to check with some others first.
Either way I feel quite good about the test overall , but until I recieve the letter in the mail there will always be that question.
 
Re: Test Question

they called for type thw - 75 degree column-
The answers that were list ed on the answer sheet were : A) 1 awg
B) 2 awg
C) 3/0 awg
D) 4/0 awg
 
Re: Test Question

If that is all the info they gave you, then 2/0 copper sounds correct, with a 175A OCPD.

The heater would of course have multiple smaller heating elements with their own OCP, & would probably have a fan motor.
But again, if that is all they tell you, I do not know what they are looking for.
 
Re: Test Question

So which answer did you choose? I would have chosen C) 3/0, since A) and B) are too small.
 
Re: Test Question

Seeing how the test was a paper test and not a computer test I chose 3/0 then wrote 2/0 with an explaination in the border. The same for the question about the pipe size for said heater. I chose the correct size for the 3/0 answer then wrote in the size for 2/0 with an explaination.
But I am going to call the Electrical Board that gave the test to verify I'm correct either way. The test prep course I took prior to the test was given by the chief inspector who is a member of the board. He told us that this type of thing would not be on the test.
 
Re: Test Question

I am not saying you did this, but here is my experience with some questions like this.

When reading these questions, sometimes certain details escape your attention. Did the question mention anything about ambient temperature? It would not say ambient temperature, but it would state the feeder is installed in a room of say 100 degree F. There may have been some type of ampacity adjustment factor in the question that you may have missed.
Just asking.
 
Re: Test Question

No - the question said nothing about temp. so no derating was involved.
I will post what the board tells me when I talk to them.
Ken
 
Re: Test Question

I called the electrical board today. We went over the question and answer over the phone. The electrical board member informed me I was correct and I will be given credit for the 2 questions. He said they will most likely give credit to whoever chose 3/0 or wrote in 2/0
 
Re: Test Question

Questions can be tricky. If they did not state "What is the minimum size conductor allowed for the load", in reality there are two correct answers, 3/0 and 4/0 cu.
 
Re: Test Question

I just received the results of the masters test I took. I passed with a 88% .
I don't mean to toot my own horn ...
well maybe just this one time. :D
 
Re: Test Question

I second Ryan's Congratulations, good job.
icon14.gif


Roger
 
Status
Not open for further replies.
Top