25 foot tap rule

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cppoly

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Question #11

A feeder tap less than 25 feet long does not require overcurrent protection at the tap if the ampacity of the tap conductor is at least:

  1. 50% of the feeder conductor
  2. 40% of the feeder conductor
  3. 33 1/3% of the feeder conductor
  4. 20% of the feeder conductor


Shouldn't the answers say feeder OCPD and not feeder conductor??
 
Of the top of my head it's the conductor not the OCPD but I haven't looked to clarify that.

JAP>
 
You can assume that the feeder you are tapping from will be protected at its ampacity or lower.
So you need to look at the ampacity of the tap conductor, not the OCPD at the far end of the tap.
If the feeder is oversized for its OCPD you are still limited, IMHO.

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cppoly said:
Question #11

A feeder tap less than 25 feet long does not require overcurrent protection at the tap if the ampacity of the tap conductor is at least:

  1. 50% of the feeder conductor
  2. 40% of the feeder conductor
  3. 33 1/3% of the feeder conductor
  4. 20% of the feeder conductor


Shouldn't the answers say feeder OCPD and not feeder conductor??
Click to expand...

You are correct. 33 1/3% of the rating of the OCPD protecting the feeder conductors.
 
jap said:
Of the top of my head it's the conductor not the OCPD but I haven't looked to clarify that.

JAP>
Click to expand...

Looked it up and and you are correct.
It should be the "Rating of the Overcurrent Device protecting the Feeder"


JAP>
 
cppoly said:
Question #11

A feeder tap less than 25 feet long does not require overcurrent protection at the tap if the ampacity of the tap conductor is at least:

  1. 50% of the feeder conductor
  2. 40% of the feeder conductor
  3. 33 1/3% of the feeder conductor
  4. 20% of the feeder conductor


Shouldn't the answers say feeder OCPD and not feeder conductor??
Click to expand...
Part I bolded for you is what can cause confusion with this question. If there is overcurrent protection "at the tap" then you don't have a feeder tap. "of the feeder conductor" is also not right in every one of the possible answers. Feeder could be "oversized conductors" but it is still overcurrent protection setting that matters the most when determining minimum tap conductor size allowed.

Possible question to replace that one with: A feeder tap up to 25 feet in length must have ampacity no less than_____ of the feeder overcurrent protective device setting.
 
kwired said:
Part I bolded for you is what can cause confusion with this question. If there is overcurrent protection "at the tap" then you don't have a feeder tap. "of the feeder conductor" is also not right in every one of the possible answers. Feeder could be "oversized conductors" but it is still overcurrent protection setting that matters the most when determining minimum tap conductor size allowed.

Possible question to replace that one with: A feeder tap up to 25 feet in length must have ampacity no less than_____ of the feeder overcurrent protective device setting.
Click to expand...
Unless, of course, it is also shorter than 10 feet....
 
david luchini said:
The part that you bolded borrows the text from 240.21(B).
Click to expand...
The part of OP's quote that I bolded " does not require overcurrent protection at the tap" I did not look into, but highly doubt that is directly from NEC at all. What you bolded of my quote, does sound like language NEC would use, I didn't intentionally copy or quote anything, just how I thought such a question should be worded, the more it is like what the NEC actually says the more appropriate IMO for such questioning.
 
kwired said:
The part of OP's quote that I bolded " does not require overcurrent protection at the tap" I did not look into, but highly doubt that is directly from NEC at all. What you bolded of my quote, does sound like language NEC would use, I didn't intentionally copy or quote anything, just how I thought such a question should be worded, the more it is like what the NEC actually says the more appropriate IMO for such questioning.
Click to expand...

Here's what the NEC says...

240.21(B) Feeder Taps. Conductors shall be permitted to be tapped, without overcurrent protection at the tap, to a feeder as specified in 240.21(B)(1) through (B)(5).
Click to expand...

The language in the question is very much like the language in the Code.
 
kwired said:
Part I bolded for you is what can cause confusion with this question. If there is overcurrent protection "at the tap" then you don't have a feeder tap. "of the feeder conductor" is also not right in every one of the possible answers. Feeder could be "oversized conductors" but it is still overcurrent protection setting that matters the most when determining minimum tap conductor size allowed.

Possible question to replace that one with: A feeder tap up to 25 feet in length must have ampacity no less than_____ of the feeder overcurrent protective device setting.
Click to expand...
Tap connectors can originate at an OCPD that has a rating higher than that of the connected conductors.
10-45 Log #4825 NEC-P10 Final Action: Reject
(240.21(B))
_______________________________________________________________
Submitter: Don Ganiere, Ottawa, IL
Recommendation: Add text to read as follows:
(B) Feeder Taps. Conductors shall be permitted to be tapped, without overcurrent protection at the tap, to a feeder as specified in 240.21(B)(1)
through (B)(5). Feeder taps shall be permitted to originate at the load terminal of an overcurrent protective device. The provisions of 240.4(B) shall not be
permitted for tap conductors.
Substantiation: This type of installation is permitted in many areas, but the code does not specifically permit it. The additional wording will make it clear
that this is a code compliant installation. As long as all of the conditions of this section are complied with the point of origination of the tap conductor does not
create any additional hazard.
Panel Meeting Action: Reject
Panel Statement: The proposed language is not necessary as the present language permits such installation where appropriate.
Number Eligible to Vote: 12
Ballot Results: Affirmative: 12
blue text = proposed
Click to expand...
 
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