Can I apply 240.4(B) to conductors to wireway?

Dennis Alwon

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
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Retired Electrical Contractor
As I read 240.4(B) I see an overcurrent protective device ahead of the conductors. Does the conductors coming in have an overcurrent protective device ahead of them?
 
augie47

augie47

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Tennessee
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State Electrical Inspector (Retired)
For the conductors identified, assuming there is no over-current protection ahead of them and assuming they are service conductors, the correct size be be derived form 230.42 based on a load calculation.
 
W

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
The OP's question, in looking for an allowance in 240.4 for protection of the conductors in question, reveals 240.4 has none. As such 240.4 conflicts with the allowance in 230.90(A) Exception 3. Looks like we need a 2029 PI for a new section 240.4(I) that references 230.90(A) Exception 3--there weren't any such PIs submitted for 2026.

Cheers, Wayne
 
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R

Rock86

Senior Member
Location
new york
Occupation
Electrical Engineer / Electrician
Are you asking if you can use an 800A OCPD ahead of the two meters, and if the (2) sets of 500mcm will be acceptable under 240.4(B) because that overcurrent would be 800A? And is your intent to come off of that 800A OCPD with the conductors shown to the meters? I would say, and anyone please correct me if I am wrong, if your load calculations permits you to use an 800A OCPD, you should be permitted to abide by 240.4(B).
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Rock86 said:
Are you asking if you can use an 800A OCPD ahead of the two meters, and if the (2) sets of 500mcm will be acceptable under 240.4(B) because that overcurrent would be 800A? And is your intent to come off of that 800A OCPD with the conductors shown to the meters? I would say, and anyone please correct me if I am wrong, if your load calculations permits you to use an 800A OCPD, you should be permitted to abide by 240.4(B).
Click to expand...

The problem is there is no overcurrent protective device before those service cables. 240.4(B), imo seems to indicate that we can upsize the overcurrent protective device protecting the conductors...
 
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