Table 310.15(B)(6)

[cruiser1340]

Table 310.15(B)(6) states 120/240 volt. Does this Table also apply to 120/208volt 3-wire Single Phase Dwelling Service? Utility Companies are supplying this type of service to family dwellings from a 3 Phase 4-wire system. I have found this in new housing developments.

 

[Dennis Alwon]

Table 310.15(B)(6) states 120/240 volt. Does this Table also apply to 120/208volt 3-wire Single Phase Dwelling Service? Utility Companies are supplying this type of service to family dwellings from a 3 Phase 4-wire system. I have found this in new housing developments.

The NEC states clearly 120/240 so I would say you cannot use this table with 120/208

 

[raider1]

I agree with Dennis, Table 310.15(B)(6) can't be used for the ampacity of a 3 wire 208/120 volt feeder to a dwelling unit.

Chris

 

[charlie b]

I agree with Dennis, Table 310.15(B)(6) can't be used for the ampacity of a . . . .

I also agree. But to that I will add that I think that table cannot be used for the ampacity of anything at all. The word "ampacity" does not appear anywhere in the table or in the text that refers to it. But that is somewhat off topic, so I won't pursue the argument here.

 

[Dennis Alwon]

I also agree. But to that I will add that I think that table cannot be used for the ampacity of anything at all. The word "ampacity" does not appear anywhere in the table or in the text that refers to it. But that is somewhat off topic, so I won't pursue the argument here.

So are you saying that since the word "amperes" is in the table but not the word "ampacity" that the Table is no good.

 

[david luchini]

So are you saying that since the word "amperes" is in the table but not the word "ampacity" that the Table is no good.

Dennis, Charlie didn't say that the table was "no good." He only said that the table is not used to determine "ampacity" of a conductor size.

A #4 Cu conductor in would still have an ampacity of 85, but T310.15(B)(6) would "permit" that conductor to be used on a 100A, 120/240 Single phase dwelling service.

Think of it the same was that 240.4(B) "permits" the next higher standard OCPD. By 240.4(B), you could protect a 500mcm cu conductor with a 400A OCPD. But the ampacity of the conductor is still 380, not 400.

 

[raider1]

I also agree. But to that I will add that I think that table cannot be used for the ampacity of anything at all. The word "ampacity" does not appear anywhere in the table or in the text that refers to it. But that is somewhat off topic, so I won't pursue the argument here.

Good point Charlie.

Chris

 

[jumper]

Dennis, Charlie didn't say that the table was "no good." He only said that the table is not used to determine "ampacity" of a conductor size.

A #4 Cu conductor in would still have an ampacity of 85, but T310.15(B)(6) would "permit" that conductor to be used on a 100A, 120/240 Single phase dwelling service.

Think of it the same was that 240.4(B) "permits" the next higher standard OCPD. By 240.4(B), you could protect a 500mcm cu conductor with a 400A OCPD. But the ampacity of the conductor is still 380, not 400.

This is what I was thinking also.

 

[charlie b]

A #4 Cu conductor in would still have an ampacity of 85, but T310.15(B)(6) would "permit" that conductor to be used on a 100A, 120/240 Single phase dwelling service.

That is how I see it. I also believe that this table does not declare that the ampacity of a #4 is 100 amps, under the specific "conditions of use" to which the table applies. Furthermore, it does not declare that a pair of #4 in parallel can be used for a 200 amp service, nor that the ampacity of a pair of #4 would be 200 amps.

 

[jumper]

That is how I see it. I also believe that this table does not declare that the ampacity of a #4 is 100 amps, under the specific "conditions of use" to which the table applies. Furthermore, it does not declare that a pair of #4 in parallel can be used for a 200 amp service, nor that the ampacity of a pair of #4 would be 200 amps.

I agree, it is a specific chart for resi apps, not a substitute for 310.16 calcs.

 

[don_resqcapt19]

That is how I see it. I also believe that this table does not declare that the ampacity of a #4 is 100 amps, under the specific "conditions of use" to which the table applies. Furthermore, it does not declare that a pair of #4 in parallel can be used for a 200 amp service, nor that the ampacity of a pair of #4 would be 200 amps.

The code making panel does not agree. This is the panel statement from comment 6-32 for the 1995 code cycle.

PANEL STATEMENT: The service or feeder ratings in the tabular portion of Note 3 are permissible current ratings for the wire sizes indicated, similar to the allowable ampacities permitted in Table 310-16 through Table 310-19. ...

Note 3 in the 1995 code is the rule that is 310.15(B)(6) in the 2008 code.

 

[charlie b]

The code making panel does not agree. This is the panel statement from comment 6-32 for the 1995 code cycle.

If they think the numbers are ampacities, then they should revise the code itself to say that, for as written it does not. Panel statements are neither enforceable by an AHJ nor usable by an EC.

I submitted a proposal for 2011, hoping to clarify that the numbers were not ampacities, and that parallel conductors cannot be based on the sizes shown in the table. In their ROP they disagreed that the numbers are not ampacities. I then submitted a comment in response to that item in the ROP, stating that they should then revise the table to include the word "ampacities" in some appropriate context. I have not read the related ROC, nor have I seen the final version of the 2011 article. So I don't know what they did with my comment.

 

[raider1]

Here is the ROC Charlie.

_______________________________________________________________
6-60 Log #2234 NEC-P06 Final Action: Reject
(310.15(B)(6), FPN )
_______________________________________________________________
Submitter: Charles E. Beck, Affiliated Engineers NW, Inc.
Comment on Proposal No: 6-86
Recommendation: Add the following Fine Print Note at the bottom of Table
310.15(B)(6):
FPN: The ?Service or Feeder Ratings? shown in the above table shall be
permitted to be considered the ampacities of the associated conductors only for
the specific conditions of use that are addressed in this article.
Substantiation: The ?Panel Statement? describing the reason for rejecting
this proposal describes the values in the table with the following words, ?The
conductor ampacities listed in 310.15(B)(6)...?. But nothing in the table itself,
and nothing in the text that refers to the table, includes the word ?ampacities.?
All the table presently permits is certain conductors to be used for certain
service or feeder ratings. That is not the same thing. If the CMP wishes to
permit the table to be used as an ampacity table, then the fact should be stated
in the table itself, or in the article that refers to the table.
Panel Meeting Action: Reject
Panel Statement: The Rule Governing Committee projects does not permit
mandatory language in Informational Notes (FPN). See the panel action and
statement on Comment 6-55.
Number Eligible to Vote: 11
Ballot Results: Affirmative: 11
Comment on Affirmative:
PICARD, P.: See comment on Comment 6-55.

Chris

 

[texie]

table 310.15(B)(6)

table 310.15(B)(6)

I believe this is not allowed for 120/208 single phase service because the neutral carries full current when tapped from a 120/208 3 phase network.

 

[don_resqcapt19]

.... Panel statements are neither enforceable by an AHJ nor usable by an EC.
...

As far as I am concerned, there is only one thing that trumps a panel statement...that would be a Formal Interpretation. They are often used by both AHJs and ECs to support their interpretation of a code rule.

In the rare event that a dispute over the meaning of a code rule would ever reach the courts, the courts would use the panel statements in the ROPs and ROCs just like they now use the "legislative" history of a civil or criminal law to help them come to a decision on what a law means. The ROPs and ROCs are the legislative history of the code rules.

 

[iwire]

As far as I am concerned, there is only one thing that trumps a panel statement...that would be a Formal Interpretation. They are often used by both AHJs and ECs to support their interpretation of a code rule.

I don't think there is room for interpretation here.

The words in 310.15(B)(6) and Table 310.15(B)(6) do not support using that table for any service size not listed in the table.

 

[charlie b]

Here is the ROC Charlie.

Thanks, Chris. It seems that the CMP didn't understand the problem. Maybe in my proposal for 2011 I should use Charlie's Rule as the substantiation. :roll: