more 110.14(C)(1)

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hardworkingstiff

Senior Member
Location
Wilmington, NC
OK, everyone knows I use W cable at marinas and I've been using table 400.5(B) for ampacities. Now I understand that I'm limited to table 310.16 ampacities because of 110.14(C)(1). I believe it has been presented that splicing a piece of THWN (with 310.16 ampacity selection) onto the W cable (400.5(B) ampacities) before the termination (breaker) will bring the termination into compliance with 110.14(C)(1) for the breaker. {If I've misunderstood what was posted on this site, please correct me}.

At the marine power center it's just not pratical to make this same splice at the busbar of the power center. Another thought came to mind. The busbar is rated for 250-amps (I believe) and 75C (maybe 90C) connections. If we are wiring a piece of #4 W cable with OCP of 100-amps (allowed by table 400.5(B)) and landing it (with proper ring terminals) on the 250-amp rated busbar, are we OK since the busbar won't heat up at 100-amps (being it's rated 250-amps), the cable is rated for 100-amps (at 75C), the ring terminals are rated 90C+?

I don't see this as a problem, but I don't know if will comply with the "letter of the law".

Comments please/thanks,
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
Is there any way to take advantage of the second sentence of 110.14(C)(1)? I am specifically talking about the part before the comma, the part that says "Unless the equipment is listed and marked otherwise." Is is possible that "the equipment," which I think would refer to the marine power center, could be listed and marked for the use of type W wires? Wouldn't that allow you to use the 400.5(B) ampacities as the basis for the terminal provisions?
 

hardworkingstiff

Senior Member
Location
Wilmington, NC
Is there any way to take advantage of the second sentence of 110.14(C)(1)? I am specifically talking about the part before the comma, the part that says "Unless the equipment is listed and marked otherwise." Is is possible that "the equipment," which I think would refer to the marine power center, could be listed and marked for the use of type W wires? Wouldn't that allow you to use the 400.5(B) ampacities as the basis for the terminal provisions?

Charlie,

I spoke with the EE at the factory and he is looking into doing just that. I'm just trying to get as best an understanding of this issue as I can.
 

Smart $

Esteemed Member
Location
Ohio
Let me see if I understand you correctly...

  • At the OCPD end you are splicing on a section of #3 THWN rated for 100A @ 75?C per T310.16? How long? Judging from another thread, it needs to be at least 4' long.
  • At the other end, you want to terminate the #4 Type W conductors to a 90?C or better rated lug bolted to a busbar rated for 250A inside the power center?


In addition to charlie b's question, is there any temperature rating associated with the busbar specifically or the power center in general?

What is the temperature rating of the Type W cable?
 

hardworkingstiff

Senior Member
Location
Wilmington, NC
Let me see if I understand you correctly...

  • At the OCPD end you are splicing on a section of #3 THWN rated for 100A @ 75?C per T310.16? How long? Judging from another thread, it needs to be at least 4' long.
  • Yes, that's what I was thinking could be a solution. Based on Jim Dunger's post, it looks like 4' of #3 is the length needed.
    [*]At the other end, you want to terminate the #4 Type W conductors to a 90?C or better rated lug bolted to a busbar rated for 250A inside the power center?
    Correct. The power center manufacturer uses the same busbar for all configurations. So it seems if the connected load is 100-amps that heat won't be a problem.
In addition to charlie b's question, is there any temperature rating associated with the busbar specifically or the power center in general?
I'm waiting on response from the EE at the power center manufacturer.
What is the temperature rating of the Type W cable?
90C dry, 75C wet. Using column E of the 75C grouping of table 400.5(B) the rating of a #4 W cable is 115-amps. So at 100-amps, we are not approaching the cable ampacity at 75C.

This is very interesting stuff.
 
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