Need help with test question #2

[Artical430]

A trade size 1 in. Schedule 40 PVC conduit is run horizontally out of the side of a panel board for 50 feet, then turns at a 90 degree angle vertically for 40 feet where it enters the building through a LB conduit body. How many expansion fittings are required for this installation?
A. One
B. Two
C. Three
D. Four

 

[GoldDigger]

Again, tell us how you would start, or get no answer....

 

[Artical430]

Well ....I know expansion fittings are covered in arrival 352....but I can not understand how you determine how many expansion fittings you need for this length of a run...

 

[GoldDigger]

Is the point where the PVC makes the right angle bend fastened down or is it free to move? If it is fastened, you have two runs, each of which may require one or more expansion joints. How does the number of joints relate to the length of the run for PVC?

 

[Artical430]

Artical 352...table 352.30 trade size 1 in states that the PVC has to be supported every 3 feet or with in every 3 feet...I am trying to decipher table 352.44

 

[jusme123]

Elbows are considered ‘securely mounted’, as noted in 352.44.

 

[GoldDigger]

Elbows are considered ‘securely mounted’, as noted in 352.44.

Exactly. Along the length on either side of the elbow, it is critical that the fittings spaced out every three feet are there to support the pipe, not to secure it. So it is free to move within those support brackets as it expands and contracts. But the elbow is considered to be fixed in space, so there are two runs of pipe that need to be separately considered as requiring expansion joints. Now the remaining question is how many joints for a 50' and for a 40' section.

 

[Artical430]

Are you suggesting that the question is poorly written...because the only information that the question gives is....
A trade size 1 inch schedule 40 PVC conduit is run horizontally out of the side of a panel board for 50 feet, then turns at a 90 degree angle vertically for 40 feet where it enters the building through a LB conduit body..How many expansion fittings are required for this installation...
A. One
B. Two
C. Three
D. Four...

 

[infinity]

Are you suggesting that the question is poorly written...because the only information that the question gives is....
A trade size 1 inch schedule 40 PVC conduit is run horizontally out of the side of a panel board for 50 feet, then turns at a 90 degree angle vertically for 40 feet where it enters the building through a LB conduit body..How many expansion fittings are required for this installation...
A. One
B. Two
C. Three
D. Four...

You need to know that elbows (post #6) are considered securely mounted so use the total length of each section for the calculation.

 

[ptonsparky]

What is your temperature change?

 

[Artical430]

I was looking or studying table 352.44...to try and figure this question out...but I am at a total lost...
I have...tho....been studying for some time...and I understand that some questions are poorly written....do you believe that is the case with this question...

 

[augie47]

IMO, the size of the conduit is irrelevant, a 40 ft and 50 ft run of PVC is likely to need expansion joints in a environment where its subject to temperature changes.. Since it says "entering the building" you can assume its outside and will need joints, With the panel on one end and the LB on the other and a 90° turn involved, I would feel safe answering "two", one of the 50 ft run, and one on the 40.
In this case you don't need to worry about the Table as you know you will need an expansion joint in each section that is fixed at both ends.

 

[infinity]

IMO, the size of the conduit is irrelevant, a 40 ft and 50 ft run of PVC is likely to need expansion joints in a environment where its subject to temperature changes.. Since it says "entering the building" you can assume its outside and will need joints, With the panel on one end and the LB on the other and a 90° turn involved, I would feel safe answering "two", one of the 50 ft run, and one on the 40.
In this case you don't need to worry about the Table as you know you will need an expansion joint in each section that is fixed at both ends.

I believe that is what they're asking but if the temperature change we're only 5° then the answer might be different.

 

[Artical430]

Do you guys believe that this question is General knowledge type of question..because some questions in the answer book is marked general knowledge...I only have maybe 3000 hours in the electrical trade..but I am already studying the book part..

 

[infinity]

Do you guys believe that this question is General knowledge type of question..because some questions in the answer book is marked general knowledge...I only have maybe 3000 hours in the electrical trade..but I am already studying the book part..

It tests your ability to decipher what the person who wrote the question is actually asking and how to find the relevant information in the codebook. The question is particularly vague in that it does not include any amount temperature change which would be need to use the expansion table in the NEC.

 

[Artical430]

It tests your ability to decipher what the person who wrote the question is actually asking and how to find the relevant information in the codebook. The question is particularly vague in that it does not include any amount temperature change which would be need to use the expansion table in the NEC.

Very well put...thank you for that explanation..I now understand..

 

[Another C10]

How many expansion fittings are required for this installation?

I would run Emt .. My guess off the hip would be (A) 1 expansion fitting just for the penetration, and 1" one hole Rigid straps every 3 ft. But I could be wrong.

 

[Another C10]

has to be supported every 3 feet

wow .. I guessed that one pretty accurate , pat on the back for me. ")