Box cubic inch calculation

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mark32

Senior Member
Location
Currently in NJ
The other day I was calculating the cubic inches of an 8x8x4 and realized that I must be doing something wrong. Reason being, I checked my formula by calculating a 4x4x1.5 box. I get 24 but according to 314.16, they come up with 21. How do they arrive at 21?
 

active1

Senior Member
Location
Las Vegas
In Raco catilog the 4x4x1.5 boxes all seem to be 21 ci.
My guess would be inside diameter less than outside and outside is less than trade size.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
active1 said:
In Raco catilog the 4x4x1.5 boxes all seem to be 21 ci.
My guess would be inside diameter less than outside and outside is less than trade size.

That is exactly correct. The dimensions of the box are not the inside dimensions but the outside dimensions. The calculation must be done with the inside dimensions.
 
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