Art. 110.14(c)1 and 2. Does this rule apply to transformers, feeders, and all motors including b,c,d. The reason I ask is that Iam reviewing stallcup journeyman test workbook and a few questions dont make sense to me. ex.The primary of a 45 kva 440 volt 3-phase transformer is supplied with THW. Calculate the ampacity of the OCPD for the primary conductors. Answer No. 6, THW with 70 amp OCPD. Table 310.16 They used the 75 degree shouldent they have used the 60 degree if the terminal rating wasent lited? any code ref. would be apprecated.
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temperature limitations
- Thread starter donmore
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Re: temperature limitations
In your question,(*is supplied with THW.)
The insulation on THW, is rated for 75 degree C.
In 110.14(C)(1)(A)(1)*Conductors rated 60 degree C.
When you do go to test,watch for the insulation of the conductors, in your test questions,in useing 310.16 table
I better add this..THW-2 is rated for 90 degree C, but that column is only for the adjustment factors in 310.16 table..(don't get them mixed)
[ September 15, 2005, 11:08 PM: Message edited by: dillon3c ]
donmore,Originally posted by donmore:
The primary of a 45 kva 440 volt 3-phase transformer is supplied with THW. Calculate the ampacity of the OCPD for the primary conductors. Answer No. 6, THW with 70 amp OCPD. Table 310.16 They used the 75 degree shouldent they have used the 60 degree if the terminal rating wasent lited? any code ref. would be apprecated.
In your question,(*is supplied with THW.)
The insulation on THW, is rated for 75 degree C.
In 110.14(C)(1)(A)(1)*Conductors rated 60 degree C.
When you do go to test,watch for the insulation of the conductors, in your test questions,in useing 310.16 table
I better add this..THW-2 is rated for 90 degree C, but that column is only for the adjustment factors in 310.16 table..(don't get them mixed)
[ September 15, 2005, 11:08 PM: Message edited by: dillon3c ]
Re: temperature limitations
For the past several years I have looked at the temperature ratings for connections on disconnects, devices, motors, etc. Rarely have I found a temperature rating for 60?C unless it is older equipment. Most all of these are rated at 75?C and some of the new stuff is rated at 90?C. Most of the test questions I have seen lately are written with the implication of using 75?C terminations. I don?t know if the writers are assuming that most connections are rated at 75?C practically or think most people would use a 75?C terminal if the question uses a 75?C rated wire. Looking at the answer may give you a clue as to the intent of the question writer. My opinion is that the question writer should include the temperature rating of the terminal along with the wire acronym. Hope this helps you. Good luck with the study. Self-discipline is the key to all learning and education teaches you the discipline to do things when you don?t feel like doing the work.
For the past several years I have looked at the temperature ratings for connections on disconnects, devices, motors, etc. Rarely have I found a temperature rating for 60?C unless it is older equipment. Most all of these are rated at 75?C and some of the new stuff is rated at 90?C. Most of the test questions I have seen lately are written with the implication of using 75?C terminations. I don?t know if the writers are assuming that most connections are rated at 75?C practically or think most people would use a 75?C terminal if the question uses a 75?C rated wire. Looking at the answer may give you a clue as to the intent of the question writer. My opinion is that the question writer should include the temperature rating of the terminal along with the wire acronym. Hope this helps you. Good luck with the study. Self-discipline is the key to all learning and education teaches you the discipline to do things when you don?t feel like doing the work.
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