Termination Temperature Rating

[jdscott]

I am a design engineer (let the abuse begin). What is the best source of information in advance of the equipment arriving on site to determine equipment termination temperature ratings? I could use 60 deg C on everything, but that seems like overkill and would add additional costs in every design.

Does anyone ever see 60 deg C terminations? Are most terminations 60/75 deg C or 75 deg C?

Any rules of thumb for motor, HVAC, MCCs, panelboards, etc.?

For example, if I planning for packaged heat pump (say Carrier or Trane) and the HVAC designers says that the MCA is 75A. Can I start with the 75 deg C column of Table 310.15(B)(16) or should I start with the 60 deg C column? (Note that a lot of HVAC in water/wastewater plants is on the roof so I would correct for temperature thereafter).

It seems like NEC 110.14 tells us to assume 60 deg C if <=100A and 75 deg C if >100A unless we know more from the manf. Am I reading that correctly?

Any thoughts are appreciated.

Thanks.

 

[publicgood]

You should do some searching, as there are many forums posts on this topic. In short, you are reading 110.14 correctly. You'll find, short of upfront information, using 60C for less than 100A isn't a significant cost difference.

 

[infinity]

It seems like NEC 110.14 tells us to assume 60 deg C if <=100A and 75 deg C if >100A unless we know more from the manf. Am I reading that correctly?

Any thoughts are appreciated.

Thanks.

You're correct and 110.14 is a good guideline when you simply do not know if the equipment has 60° or 75° C terminals.

 

[oldsparky52]

When's the last time someone saw 60c limitations on equipment, even under 100A?

 

[infinity]

When's the last time someone saw 60c limitations on equipment, even under 100A?

I believe that most receptacles terminals have a 60° rating. I recently installed a 50 amp generator inlet box with #8/3 MC cable that had 60° C terminals so I had to tail off the #8's with #6's to connect to the device. For other equipment like disconnect switches (except for the $12 AC pull out types) I would guess that many would have 75° C terminals.

 

[oldsparky52]

I believe that most receptacles terminals have a 60° rating.

I agree, but wouldn't exactly call a receptacle "equipment"

 

[ron]

Generally 100A and under is 60 deg unless proven otherwise.

I have a colleague that indicates on the drawings that all equipment shall be proved with 75deg terminations, and then specifies as such. Very few if any 60deg terms still existing that wouldn't already have 15A or 20A wire already assigned by the code.

 

[rbalex]

I agree, but wouldn't exactly call a receptacle "equipment"

You might not but equipment is a defined term in the NEC:

Equipment. A general term, including fittings, devices, appliances,
luminaires, apparatus, machinery, and the like used as a
part of, or in connection with, an electrical installation.

 

[oldsparky52]

You might not but equipment is a defined term in the NEC:

OK! But .... in the reference of this thread, I believe the OP was NOT thinking about receptacles.

What is the best source of information in advance of the equipment arriving on site to determine equipment termination temperature ratings?

I tend to forget we are borderline attorneys on this site,

 

[infinity]

OK! But .... in the reference of this thread, I believe the OP was NOT thinking about receptacles.



I tend to forget we are borderline attorneys on this site,

You're correct receptacles probably aren't germane to the conversation in the OP. I was just providing some examples to illustrate that 60 degree C terminals still exist.