Ampacity

[mstrlucky74]

I just go some MH videos in the mail. Boy does he like to highlight. He states the for loads under 100a the 60 degree column is to be used for ampacity. Is that correct? I am going somewhat off memory right now and I was falling asleep on train while watching...

 

[Dennis Alwon]

I just go some MH videos in the mail. Boy does he like to highlight. He states the for loads under 100a the 60 degree column is to be used for ampacity. Is that correct? I am going somewhat off memory right now and I was falling asleep on train while watching...

If the termination are not marked yes that is correct however if the terminations are rated 75C and the conductor is rated 75C or greater than you can use the 75C column

 

[mstrlucky74]

If the termination are not marked yes that is correct however if the terminations are rated 75C and the conductor is rated 75C or greater than you can use the 75C column

Thanks....I would imagine most terminals are marked.

 

[Dennis Alwon]

Thanks....I would imagine most terminals are marked.

Not necessarily in older panels where labels get ruined or missing. New panels are all 75C that I have seen.

 

[mbrooke]

You would follow the rating of the device. Nearly all devices today are rated 75c.

 

[haskindm]

See article 110.14. To be listed a terminal rated 100 amps or less and for #14 through #1 AWG wires must be rated for at least 60 degrees C. So you must asume that an unmarked terminal is rated 60 degrees. If it is rated higher it would need to say so. If it is rated 75 degrees (most are) it will be marked and you may use that rating if the conductors are rated at least 75 degrees.

 

[kwired]

I think you will find that most 20 year old equipment is marked 75C. So you need to start looking more carefully into just how old is existing equipment.

General rule is that new construction will have very few 60C equipment.

If existing you better either figure 60C or investigate before assuming 75C.

 

[mstrlucky74]

Thanks.

 

[jumper]

Note that some terminations are 90C and you can use them for full ampacity in certain conditions.

Here is a example. I stole it from Iwire.

 

[Dennis Alwon]

Here is a nice graphic that may help you when looking at lugs. This is from Electrical Contractor Magazine.

 

[jumper]

Nice graphic Dennis, adding that to my collection.:thumbsup:

 

[Greg1707]

confusion regarding 110.14c1a

confusion regarding 110.14c1a

I am really confused about this. I thought that all conductors under 100 amp or less than 1awg were required to use the 60 degree column for determining ampacity. In fact this article states: "Conductors rated 100 amperes or less or marked for sizes. . . shall have their ampacity ratings based on 60 degrees." There is a period after that sentence. This seems to be very clear. I assumed the sentences following this applied to conductors other than listed in the first sentence, i.e. over 100 amps or 1 awg?

 

[jim dungar]

Here is a nice graphic that may help you when looking at lugs. This is from Electrical Contractor Magazine.

In my opinion this is a very misleading graphic. It is showing only lug/terminal ratings, not termination ratings.

Termination ratings are provided by the manufacturer of the equipment and include the lug as well as the connection point and ambient air.

You cannot increase ta device's termination temperature rating simply by changing to a higher rated lug/terminal.

 

[texie]

In my opinion this is a very misleading graphic. It is showing only lug/terminal ratings, not termination ratings.

Termination ratings are provided by the manufacturer of the equipment and include the lug as well as the connection point and ambient air.

You cannot increase ta device's termination temperature rating simply by changing to a higher rated lug/terminal.

Yes, that is a good observation and I agree. I think many may have thought otherwise.

 

[kwired]

In my opinion this is a very misleading graphic. It is showing only lug/terminal ratings, not termination ratings.

Termination ratings are provided by the manufacturer of the equipment and include the lug as well as the connection point and ambient air.

You cannot increase ta device's termination temperature rating simply by changing to a higher rated lug/terminal.

I agree, but attach a 75C lug to a 90C device would mean the whole assembly is now 75C.

Attach a 90 C lug to a bus bar - does the bus have a termination rating?

I was going to throw in - attach to an enclosure for equipment grounding, but temp rating just doesn't ordinarily matter for equipment grounding purposes.

I think the neutral assembly in many panelboards is 90C rated, unless there is overriding information for the panelboard as a complete assembly, the bars themselves are usually marked 90C or AL9CU.

 

[jim dungar]

I think the neutral assembly in many panelboards is 90C rated, unless there is overriding information for the panelboard as a complete assembly, the bars themselves are usually marked 90C or AL9CU.

There is almost no UL listed device that is '90?C rated', other than distribution blocks.
Most enclosed items do not have the proper ventilation to accommodate wiring sized using the 90?C columns in the NEC tables.