90C Terminations....

[Timebuilder]

It seems that few pieces of installed equipment use 90C terminations. I need some examples for a discussion I'm having. The context of the discussion is residential HVAC, but any good examples are welcome.

Thanks!

 

[kwired]

Neutral bars in panelboards are typically 90 degree rated. For the other end of a branch circuit you may have a harder time finding a device to land that neutral on that is also 90 degree rated though.

You have likely seen lugs with the marking AL9CU.

This means the lug is rated for aluminum or copper at 90 degrees. This is the lug only, the circuit breaker it is attached to is still likely only 75 degree. If not attached to an overcurrent device you have somewhat better chance of being able to use it at 90 degrees but there is always the device at the other end of the conductor that needs to be considered as it is also connected to the conductor.

 

[hmspe]

Examples? Not sure exactly what kind of examples you want.

I suggest you look at NEC 110.14. ecatalog.squared.com/pubs/Motor%20Control/0110DB9901.pdf has a good discussion of terminations.

 

[Dennis Alwon]

I suggest you give us an example that you want to discuss. There are way too many factors and unknowns to answer your question.

 

[Timebuilder]

Maybe I wasn't clear.

Name a piece of residential equipment that you know from experience which uses 90C terminations. A picture would help, but just the equipment ID would be helpful.

And no, I don't mean the panelboard.

 

[kwired]

Maybe I wasn't clear.

Name a piece of residential equipment that you know from experience which uses 90C terminations. A picture would help, but just the equipment ID would be helpful.

And no, I don't mean the panelboard.

Notice we are recieving an overwhelming number of pictures??

 

[Dennis Alwon]

Maybe I wasn't clear.

Name a piece of residential equipment that you know from experience which uses 90C terminations. A picture would help, but just the equipment ID would be helpful.

And no, I don't mean the panelboard.

Personally I have never seen a piece of equipment with 90C. If they exist it is a rare bird. The 90C is used, in almost all cases, for de-rating but the end ampacity must be based on the terminations which would generally be 75C .

 

[jim dungar]

Name a piece of residential equipment that you know from experience which uses 90C terminations. A picture would help, but just the equipment ID would be helpful.

I do not believe that UL Lists any utilization equipment with terminations rated above 75?C.
In fact, other than some power distribution blocks, I am not aware of any thing listed for use with conductors sized using the 90? column.

 

[kwired]

I do not believe that UL Lists any utilization equipment with terminations rated above 75?C.
In fact, other than some power distribution blocks, I am not aware of any thing listed for use with conductors sized using the 90? column.

Neutral bars in most panelboards are rated for 90?.

Exceptions to 210.19(A)(1) and 215.2(A)(1) permit you to size conductors to 90? here. There should be no need for the exceptions but they are there and help reinforce the idea that it can be done.

 

[templdl]

Personally. I don't believe that any would be found. The concern is not the termination itself be the device it is assemble on and what affect the additional temperature rating of the termination would have on the device. The devices that I'm aware of are designed and tested with wire applied at 75degC.
I know that with breakers it would change its thermal characteristics as the breaker was designed and calibrated based upon 60/75 or 75 deg rated wire. Applying THHN at 90deg C would be contrary to the design of the device rated for use with wire applied at 75deg C.
The bottom line is not the terminal itself but what is as included on the label of the device itself as should also be included in the associated instructions for the device.
It is to be remembered that the assembly must be considered and on the component terminal itself.

 

[Timebuilder]

So....

the answer is that neutral connections are sometimes rated for 90C, but we know of no utilization equipment that uses 90C terminations.

Thanks. Good info.

 

[K8MHZ]

So....

the answer is that neutral connections are sometimes rated for 90C, but we know of no utilization equipment that uses 90C terminations.

Thanks. Good info.

How about luminaires with 105C leads requiring 90C conductors?

But, that doesn't matter if the other end of the conductor is terminated on a 75C OCPD.

 

[jim dungar]

How about luminaires with 105C leads requiring 90C conductors?

The requirement to use 90?C insulation is not the same as allowing sizing based on the 90?C column for ampacity.

 

[K8MHZ]

The requirement to use 90?C insulation is not the same as allowing sizing based on the 90?C column for ampacity.

The requirement may not be, but if you have a factory installed lead on a luminaire made from 105C conductor fed with 90C NMB connected with a 105C wire nut, would not that part be rated at 90C, since that is the lowest temp rating at that junction?

And, if such an animal existed, the breaker feeding it was rated at 90C, would not the entire circuit be eligible for 90C rating?

 

[Marvin_Hamon]

The DC input busbars for inverters of PV systems are generally rated for 90?C terminations, as are the busbar terminals in DC combiner boxes. The terminations to fuses are rated for 75?C though so one end of the conductor is almost always going to make you use the 75?C rating.

This is specialized equipment so it probably won't be much help but I just wanted to throw in that there are some listed devices that are 90?C.

 

[jim dungar]

The requirement may not be, but if you have a factory installed lead on a luminaire made from 105C conductor fed with 90C NMB connected with a 105C wire nut, would not that part be rated at 90C, since that is the lowest temp rating at that junction?

And, if such an animal existed, the breaker feeding it was rated at 90C, would not the entire circuit be eligible for 90C rating?

Not necessarily.

Right now, UL Listed 100% rated circuit breakers require the use of 90?C insulated conductors which have been sized using the 75?C columns.

 

[kwired]

Not necessarily.

Right now, UL Listed 100% rated circuit breakers require the use of 90?C insulated conductors which have been sized using the 75?C columns.

That means to me that they are 75? terminals, but they want you to use 90? conductors. Not sure why they would want that either. 100% continuous breakers are not supposed to depend on the conductor as a heat sink like a thermal breaker depends on the conductor as a heat sink, that is why you don't need to increase ampacity by 25% in the first place for continuous loads on these 100% breakers.

 

[cadpoint]

---

Maybe I wasn't clear.

Name a piece of residential equipment that you know from experience which uses 90C terminations. A picture would help, but just the equipment ID would be helpful.

And no, I don't mean the panelboard.

Yeah, everytime the 90 degree's discussions comes around I think of a lug of plasma needing someplace to connect...

 

[jim dungar]

That means to me that they are 75? terminals, but they want you to use 90? conductors. Not sure why they would want that either. 100% continuous breakers are not supposed to depend on the conductor as a heat sink like a thermal breaker depends on the conductor as a heat sink, that is why you don't need to increase ampacity by 25% in the first place for continuous loads on these 100% breakers.

Who says that 100% rated devices do not use the conductor as a heat sink?

 

[GearMan]

That means to me that they are 75? terminals, but they want you to use 90? conductors. Not sure why they would want that either. 100% continuous breakers are not supposed to depend on the conductor as a heat sink like a thermal breaker depends on the conductor as a heat sink, that is why you don't need to increase ampacity by 25% in the first place for continuous loads on these 100% breakers.

UL is driving this. For all breaker Mfg's, UL489 requirements are for breakers to be calibrated @
40deg C ambient and testing was done based on 75deg C ampacity. 100% rated breakers must be used with specific lugs and are for use with 90deg C cable, but it must be sized based on the
75deg C ampacity.