Conduit size for pool light ?

[mark henderson]

ok on the test it asks what trade size pvc conduit would you run for a 16/3 wire and #8 for wet niche luminaire. Ok so in 400 it says nominal insulation thickness? This isn't overall thickness. I need over all to figure my fill, it would be 2 conductors for a fill of up to 31%. My#8 from table 8 .013 were do I find my multi conductor cable overall?

 

[Fulthrotl]

ok on the test it asks what trade size pvc conduit would you run for a 16/3 wire and #8 for wet niche luminaire. Ok so in 400 it says nominal insulation thickness? This isn't overall thickness. I need over all to figure my fill, it would be 2 conductors for a fill of up to 31%. My#8 from table 8 .013 were do I find my multi conductor cable overall?

3/4"

 

[mark henderson]

3/4"

Thanks. Can you show me the math please, and where do I find overall diameter in code for multi conductor cable?

 

[Little Bill]

Thanks. Can you show me the math please, and where do I find overall diameter in code for multi conductor cable?

Chapter 9, notes to tables, note #9

9) A multiconductor cable or flexible cord of two or more
conductors shall be treated as a single conductor for calculating
percentage conduit fill area. For cables that
have elliptical cross sections, the cross-sectional area
calculation shall be based on using the major diameter
of the ellipse as a circle diameter.

I think basically it's the overall diameter of the cable.
I used 3/4" PVC for some wet niche lights a while back. Plenty of room for the light cable and the insulated #8 EGC.

 

[augie47]

Hopefully it's a test that allows you multiple resources and time, if not the questions should include the cord diameter for you.
You can find the cord diameter at manufacturers websites. For example, Southwire shows a 16/3 SJOOW diameter as 0.315.

 

[mark henderson]

Hopefully it's a test that allows you multiple resources and time, if not the questions should include the cord diameter for you.
You can find the cord diameter at manufacturers websites. For example, Southwire shows a 16/3 SJOOW diameter as 0.315.

All they allow is 2011 nec, 5 hour test 100 questions.

.315 /3.14=.100
Add. .013

.113 = 3/4 pipe

 

[mark henderson]

Wondering if may math was correct above? Do you divide the nominal by pie?

 

[augie47]

A=(3.14159)(r?)
think that gives you .0789 form you cord area

 

[mark henderson]

A=(3.14159)(r?)
think that gives you .0789 form you cord area

ok so check this please

diameter 0.315/2=0.1575
r=0.1575
r?
0.1575x0.1575=.0248062
.0248062x3.14159=.0779309

cable=.0779309+.013=.0909309

1/2 pvc only good to .088 at 31%

so the answer is still 3/4 pvc good up to .157 at 31%

 

[tom baker]

Chapter 9, notes to tables, note #9
I think basically it's the overall diameter of the cable.
I used 3/4" PVC for some wet niche lights a while back. Plenty of room for the light cable and the insulated #8 EGC.

Thats not the point. Maybe the NEC would allow 1/2" and if so that is correct answer for the test. for the job the correct answer may be 3/4".

 

[Little Bill]

Thats not the point. Maybe the NEC would allow 1/2" and if so that is correct answer for the test. for the job the correct answer may be 3/4".

I wasn't considering a test involved. I read the OP's profile and just thought he was doing an install. I didn't see the word test until I went back after your post.

But, I was only answering his question about where to find it in the NEC.

The part about me using 3/4" was only confirming what someone else had posted. Just letting him know 3/4" was large enough. I had no math to back it up, just on the job experience.