minimum cover requirements

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C. Rossi

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What is the minimum cover requirement for Rigid non-metallic below the top surface of finished grade in all conditions?
Is it 4" under a 4" concrete slab? 300.5 Table
 

raider1

Senior Member
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Location
Logan, Utah
Welcome to the forum.:)

Could you clarify the question?

As written the question can't really be answered correctly.

Chris
 

Dennis Alwon

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Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
What is the minimum cover requirement for Rigid non-metallic below the top surface of finished grade in all conditions?
Is it 4" under a 4" concrete slab? 300.5 Table

The cover requirement will vary depending on conditions. If it is subject to vehicular traffic then 24" for non dwelling. If it is a dwelling then it could be 18" with vehicular traffic.

So-- what is your specific situation or is this just a general question.
 

C. Rossi

Member
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Sorry for the confusion. My question comes from a practice test in the book, Stallcup's Journeyman Electrician's Study Guide.

The question verbatim is:

Rigid nonmetallic conduit shall be installed a least ________ in. below the top surface of finished grade.

A. 6
B. 12
C. 18
D. 24

I doesn't mention it's condition. So, I take it as minimum requirement for any and all conditions. Which would be 0 in. provided that it is under a building Table 300.5. But to pick an answer from those choices I would pick B. 12 in. with the condition that it is in a trench below 2 in thick concrete. What do you think? Really it's a bad question if they don't give you a condition.

The answers are published in another book, which I don't have. So, Occasionally I come across a question that can be ambiguous.

C.Rossi
 

cripple

Senior Member
minimum cover requirements

Since no condition is noted I would have picked C 18 inches, which is least cover before modified by the requirements listed below the first column.
 
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