Please Explain This!!!!!

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dicklaxt

Senior Member
Article 110.14(C) and I partially quote the opening statement,,,,,,,,,,

TEMPERTURE LIMITATIONS:
The temperature rating associated with the ampacity of a conductor shall be selected and coordinated so as not to exceed the lowest temperature rating of any connected termination,conductor,or device..............

explain with an example or two:-?:-?

dick
 

iwire

Moderator
Staff member
Location
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Even if you use 90 C conductors you are limited by the terminal ratings which in most cases are 75 C.

So you would select the conductor ampacity from the 75 C column of 310.16
 

cpal

Senior Member
Location
MA
Article 110.14(C) and I partially quote the opening statement,,,,,,,,,,

TEMPERTURE LIMITATIONS:
The temperature rating associated with the ampacity of a conductor shall be selected and coordinated so as not to exceed the lowest temperature rating of any connected termination,conductor,or device..............

explain with an example or two:-?:-?

dick

most 600V terminals (or less) are only listed for max operation of 75 deg. C If you install a 90 deg. C conductor its ampacity is limited to the 75 deg. C column of 310.16 T. If you have a 75 deg. term and a 60 deg. wire the wire is the weak link.
 

dicklaxt

Senior Member
Yes I interpret it to say that also,,,,,,,,,,, but how does a higher temp rating of any given wire itself affect the operating temp that the termination sees?

I am not getting anything to come together on this one,it seems to be contradiction to me..............

dick
 

iwire

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Location
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Yes I interpret it to say that also,,,,,,,,,,, but how does a higher temp rating of any given wire itself affect the operating temp that the termination sees?

I am not getting anything to come together on this one,it seems to be contradiction to me..............

dick

The idea is not to overheat the terminal.

In an extreme case a conductor loaded to its 90 C rating could cause damage to a 60 C rated terminal.
 

dicklaxt

Senior Member
I'm still confused here,,the ampacity rating of a conductor doesn't increase the operating temperature or the current draw of the device its serving.

dick
 

iwire

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Staff member
Location
Massachusetts
I'm still confused here,,the ampacity rating of a conductor doesn't increase the operating temperature or the current draw of the device its serving.

dick

The operating temperature of the conductor can most definitely increase the operating temperature of the terminal it is connected to.

Further when we think about breakers they are thermal devices that make their own heat and often if not always the design of the breaker includes the heat sink the conductor connected to it creates.

There are large breakers that require the use of 90 c conductors but the selection of conductor amapacity has to be based on 75 C. This ensures that the heat from the breaker conducting onto the conductors will not cause insulation damage to those conductors.

Copper is a very good heat conductor just as it is a good electrical conductor.
 

dicklaxt

Senior Member
No I said," The ampacity rating of the conductor" not the operating temp of the conductor............

I think what the term "exceed" in this case must mean by definition is exceeding the lower limit or in this case falling below the recommended minimum temperature of the termination.......if that is the case then it all fits together but to say that the ampacity rating of the conductor cannot exceed or be greater than connected termination temperature just doesn't seem to have any logical explanation,,,,,does that make any sense?

dick
 

mcclary's electrical

Senior Member
Location
VA
No I said," The ampacity rating of the conductor" not the operating temp of the conductor............

I think what the term "exceed" in this case must mean by definition is exceeding the lower limit or in this case falling below the recommended minimum temperature of the termination.......if that is the case then it all fits together but to say that the ampacity rating of the conductor cannot exceed or be greater than connected termination temperature just doesn't seem to have any logical explanation,,,,,does that make any sense?

dick

no, not to me

The ampacity rating can be greater, you just can't load it to that
 

dicklaxt

Senior Member
I agree with that statement but we are not talking about loading of the conductor we are talking about the rating of the conductor vs the rating of the termination,so exceeding the rating of the limits of the temination by falling below the limit is not acceptable,
dick
 
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Dennis Alwon

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Chapel Hill, NC
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Dick if a 90C wire is heated up to 90C then that heat would be transfered to the 75C terminals that the wire attaches to.

So if a wire is installed based on 90C, and the ampacity of that conductor is loaded based on the 90C rating, then there will be a lot of heat transfered to the 75C terminal.
 

dicklaxt

Senior Member
Lets go back to the OP in part,it states,,,,,,,,,,,the temperature rating associated with the ampacity of a conductor shall be selected and coordinated so as not to exceed the lowest temperature rating of any connected termination,conductor,or device..............

Now let me ask the question what does the definition of exceed mean as it relates to any of the above termination,conductor or device?

Does it mean to be less than,larger than or both ?I originally read it as "larger than" in context but by definition it was meant it can "be both" IMO,

I know we all agree inpart what "Temperature Limitations" means but we are not ageeing on what the word exceed means and that is what threw a monkey wrench in the works for me.



dick
 
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Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Is this a trick question? :) Exceed means larger than. Thus you can equal the rating or be less than the rating but you cannot have a temp. rating higher or larger than.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Dick, look at the illustration below and notice the conductor size associated with the temperature rating of all the components.

6_15_34_3_2.gif


Does that help?

Roger
 

dicklaxt

Senior Member
Dick if a 90C wire is heated up to 90C then that heat would be transfered to the 75C terminals that the wire attaches to.

So if a wire is installed based on 90C, and the ampacity of that conductor is loaded based on the 90C rating, then there will be a lot of heat transfered to the 75C terminal.

I agree 100%

No not a trick question,,,,,,,,Mr Webster says the one of the defintions of "exceed" is to go beyond a set limit

An example supporting that would be a switch(level switch,pressure switch etc) that operates within a known band width,,,,,,,,the switch actuates when you exceed its upper limit by going above or exceed its lower limit by going below the set points.

I guess I'm the only one sticking by Mr. Webster,we all have the same answer as to what can and can't be done we are just not together on how the NEC was written in "The Queens English".:D

I'm not confused after I told myself that doesn't make any sense and went back and reread it, thats when the pure definition came to light.I rest my case,whats next on the dockett.:)

dick
 

mcclary's electrical

Senior Member
Location
VA
I agree 100%

No not a trick question,,,,,,,,Mr Webster says the one of the defintions of "exceed" is to go beyond a set limit

An example supporting that would be a switch(level switch,pressure switch etc) that operates within a known band width,,,,,,,,the switch actuates when you exceed its upper limit by going above or exceed its lower limit by going below the set points.

I guess I'm the only one sticking by Mr. Webster,we all have the same answer as to what can and can't be done we are just not together on how the NEC was written in "The Queens English".:D

I'm not confused after I told myself that doesn't make any sense and went back and reread it, thats when the pure definition came to light.I rest my case,whats next on the dockett.:)

dick

17 post later and II'm still not understanding what you are questioning. Oh well, as long as you're content
 

dicklaxt

Senior Member
Dick, look at the illustration below and notice the conductor size associated with the temperature rating of all the components.

6_15_34_3_2.gif


Does that help?

Roger

I agree with this example and its exactly as the OP states in part,,,the second part is that it can't be less than 60 degree on the one example of 75 degree case if it did then it would exceed the lowest temperature rating of any of the devices.

You could also connect both with 75 degree wire and it would still be in compliance as the lowest temperature rating would not be compromised.
IE: You could hook up a 120V 1 horsepower motor with a 5KV,250 MCM,105 degree cable and still be in compliance( kinda stupid tho)just a case in point.

I am the only one seeing this play on words and definitions there of it seems.If there is a Code Author out there looking in that can shed some light on this,please speak up.

I am not convinced I'm wrong in my interpretation of 110.14 opening statement.If you look at the example with the 75 degree rated receptacle and say to yourself I can't hook this up with 60 degree wire because it would be a violation as stated where it says you cannot exceed the lowest temperature rating in the opening statement.Is that not right???

dick



dick
 

mcclary's electrical

Senior Member
Location
VA
I agree with this example and its exactly as the OP states in part,,,the second part is that it can't be less than 60 degree on the one example of 75 degree case if it did then it would exceed the lowest temperature rating of any of the devices.

You could also connect both with 75 degree wire and it would still be in compliance as the lowest temperature rating would not be compromised.
IE: You could hook up a 120V 1 horsepower motor with a 5KV,250 MCM,105 degree cable and still be in compliance( kinda stupid tho)just a case in point.

I am the only one seeing this play on words and definitions there of it seems.If there is a Code Author out there looking in that can shed some light on this,please speak up.

I am not convinced I'm wrong in my interpretation of 110.14 opening statement.If you look at the example with the 75 degree rated receptacle and say to yourself I can't hook this up with 60 degree wire because it would be a violation as stated where it says you cannot exceed the lowest temperature rating in the opening statement.Is that not right???

dick



dick

NOpe, not in my book
 

dicklaxt

Senior Member
Kinda of at an impasse here,somebody agree with me or convince me I'm dead wrong,maybe I'm dead and don't know it.:grin:

dick
 
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