# 60/75c terminals lugs WTF?



## telsa (May 22, 2015)

What that means in the real world is that they can accept Romex -- at 60 C.

They can accept MC and piped THHN at 75 C.

The dual rating is for the slow-witted. Those who can't figure out that Romex can be landed upon 75 C rated breakers -- but STILL must obey 60 C rules.

It's a MARKETING gambit. That's why it makes no logical sense.


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## 99cents (Aug 20, 2012)

telsa said:


> What that means in the real world is that they can accept Romex -- at 60 C.
> 
> They can accept MC and piped THHN at 75 C.
> 
> ...


Proof?

This slow-witted electrician wants to see the documentation.


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## Incognito (Apr 14, 2019)

telsa said:


> What that means in the real world is that they can accept Romex -- at 60 C.
> 
> They can accept MC and piped THHN at 75 C.
> 
> ...


Canadian code does not make us rate Romex (NMD90) at 60 degrees. We do have to rate the first 1.2 meters of wire for the termination temperature of the equipment it is connected to of course, but for a piece of wire running from a j-box to a j-box, we can use the wire’s rated temperature.


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## joebeadg (Oct 7, 2008)

yea, can accept thhn at 75c, but nec states conductor must be sized at lowest temp rating of device, so, WTF?


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## 99cents (Aug 20, 2012)

Incognito said:


> Canadian code does not make us rate Romex (NMD90) at 60 degrees. We do have to rate the first 1.2 meters of wire for the termination temperature of the equipment it is connected to of course, but for a piece of wire running from a j-box to a j-box, we can use the wire’s rated temperature.


How else would we comply with the 90 degree C temperature rating at light fixtures?


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## 99cents (Aug 20, 2012)

This explains it according to the CEC. I assume the NEC is similar. It makes no distinction between cable types, only a reference to conductor size.


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## Bird dog (Oct 27, 2015)

99cents said:


> This explains it according to the CEC. I assume the NEC is similar. It makes no distinction between cable types, only a reference to conductor size.


In the NEC the chart that shows insulation types includes insulation temperature. Showing 60/75 degree rating may be the manufacturer showing both listings not just the 75degree which IMO would be sufficient.


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## 99cents (Aug 20, 2012)

Bird dog said:


> In the NEC the chart that shows insulation types includes insulation temperature. Showing 60/75 degree rating may be the manufacturer showing both listings not just the 75degree which IMO would be sufficient.


Conductors in Romex and armoured cable are rated 90 degrees C. The breaker temperature rating according to our code is dependent on the wire size the breaker can accommodate, above or below #1 AWG (plus conductor temperature rating obviously).


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## HertzHound (Jan 22, 2019)

https://www.schneider-electric.com/...5/en_US/Wire Terminations 0110DB9901R2-02.pdf


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## Dennis Alwon (May 9, 2009)

joebeadg said:


> yea, can accept thhn at 75c, but nec states conductor must be sized at lowest temp rating of device, so, WTF?


Joe, nm cable has 90C conductors but the final overcurrent protective device must be sized at the lowest temp which is 60C for nm.

So many think that makes no sense.

Now when you have to de-rate it makes a lot of sense. We can de-rate from the 90C as long as the final overcurrent protective device is at the 60C.

Example

4- 12/2 nm cables bundled.... 12 thwn is rated at 30 amps at 90C 

4 x 2 conductors per cable is 8 current carrying conductors. The de-rate of 8 current carrying conductor's is 70%. 30 amps x 70% is 21 amps so we can still use a 20 amp breaker on this circuit. If we had to start at 60C we would be in trouble.

IMO, the reason nm cable is rated 60C is to avoid all the temperature de-rating in attics etc in residences. It gets difficult to figure that out so the manufacturers and the nec panels just rate nm at 60C


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## Incognito (Apr 14, 2019)

99cents said:


> Conductors in Romex and armoured cable are rated 90 degrees C. The breaker temperature rating according to our code is dependent on the wire size the breaker can accommodate, above or below #1 AWG (plus conductor temperature rating obviously).


That code 4-006(2) only applies if the equipment is not labelled with a termination temperature.

As to the breaker with dual ratings, in Ontario we have a bulletin that tells us we are permitted to use the higher of the two temp ratings. Bulletin 4-12-4


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## joebeadg (Oct 7, 2008)

OK, I think I know what the NEC means, but does not clearly explain. They want the conductor sized to the lowest temp rating of any termination. So, if on one end of a conductor the terminal has a 75c rating, but on the other end it terminates on a lug with a 60c rating, you must size the conductor based on the 60c comumn. What do you think?


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## joebanana (Dec 21, 2010)

Incognito said:


> Canadian code does not make us rate Romex (NMD90) at 60 degrees. We do have to rate the *first 1.2 meters* of wire for the termination temperature of the equipment it is connected to of course, but for a piece of wire running from a j-box to a j-box, we can use the wire’s rated temperature.


What happens after the first 1.2 meters? Isn't the rest of it rated the same?


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## Kevin (Feb 14, 2017)

joebanana said:


> What happens after the first 1.2 meters? Isn't the rest of it rated the same?


For example

The first 1.2 meters is rated for 60° (or 75°). After the first 1.2 meters, we can use the wire at 90°, which permits us to install more conductors in a conduit before having to move to a larger size. A good example would be a store I wired with EMT last year. #12 RW90 on 15 amp circuits. I could put a lot more into a pipe before having to jump to a larger size of conductor.

This also lets us use a larger conductor for the first 1.2 meters, then go to a smaller conductor to use the higher temp rating for higher amperage rating. But this I've only ever heard talked about, never seen it in practice.

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## Dennis Alwon (May 9, 2009)

joebeadg said:


> OK, I think I know what the NEC means, but does not clearly explain. They want the conductor sized to the lowest temp rating of any termination. So, if on one end of a conductor the terminal has a 75c rating, but on the other end it terminates on a lug with a 60c rating, you must size the conductor based on the 60c comumn. What do you think?


Exactly, think of a bunch of ropes tied together and the ropes have all different strengths. What is the strength of these ropes? Obviously it will as strong as the weakest link. 

A large conductor connected to smaller conductors or connected to lower temperature connections is only as strong as the weakest link.


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## Dennis Alwon (May 9, 2009)

joebeadg said:


> OK, I think I know what the NEC means, but does not clearly explain. They want the conductor sized to the lowest temp rating of any termination. So, if on one end of a conductor the terminal has a 75c rating, but on the other end it terminates on a lug with a 60c rating, you must size the conductor based on the 60c comumn. What do you think?


Exactly, think of a bunch of ropes tied together and the ropes have all different strengths. What is the strength of these ropes? Obviously it will as strong as the weakest link. 

A large conductor connected to smaller conductors or connected to lower temperature connections is only as strong as the weakest link.


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## CoolWill (Jan 5, 2019)

It's important to remember that wire is also a heatsink. Equipment is designed with that in mind. For example, I saw a 50 amp receptacle marked "Use 6 AWG minimum"... But #8 would carry the amps by code. The designers are counting on the extra copper of #6 to carry the heat away from their chintzy ass junk.


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## CoolWill (Jan 5, 2019)

60/75 degree.... I went and did some digging and according to Square D the ratings are due to how wire size affects the thermal sensitivity of the breaker. Let's say that a breaker is rated 50 amps, 75 degrees. That breaker is depending on you using a wire that will carry enough heat away from the thermal element to keep it from nuisance tripping. A 90 degree wire sized for 50 amps will be smaller and not as good of a heat conductor.

The dual marking 60/75 means that the breaker is guaranteed to work at its rating even if smaller 75 degree wire is used.


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## joebanana (Dec 21, 2010)

Kevin_Essiambre said:


> For example
> 
> The first 1.2 meters is rated for 60° (or 75°). After the first 1.2 meters, we can use the wire at 90°, which permits us to install more conductors in a conduit before having to move to a larger size. A good example would be a store I wired with EMT last year. #12 RW90 on 15 amp circuits. I could put a lot more into a pipe before having to jump to a larger size of conductor.
> 
> ...


I guess that makes sense, but cornfusing as all hell.


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## Drsparky14 (Oct 22, 2016)

Omg it states that it must be sized per the lowest device meaning if you have a 60 degree only then the whole thing must be sized accordingly. Not that if it’s dual rated you have to size to the lowest number in the dual rating. 

N00b


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## HertzHound (Jan 22, 2019)

Kevin_Essiambre said:


> For example
> 
> The first 1.2 meters is rated for 60° (or 75°). After the first 1.2 meters, we can use the wire at 90°, which permits us to install more conductors in a conduit before having to move to a larger size. A good example would be a store I wired with EMT last year. #12 RW90 on 15 amp circuits. I could put a lot more into a pipe before having to jump to a larger size of conductor.
> 
> ...


I can see that making sense at the panel where you have 1.2 meters, but what about the other end? What if you only have a 4”sq box and the wire terminates on a device. Certainly less 1.2 meters.

It’s pretty much the same as our code but the 1.2 muddies the water. We’re allowed to make the correction factor (ambient temperature) and ampacity adjustment (derating for multiple conductors) from the higher temperature rating, but the final ampacity can’t exceed the ampacity at the termination temperature. 

Does your rule somehow let you put #12 RW90 on a 30amp breaker when you have 15 current carrying conductors in a conduit and both ends have 1.2 meters of wire?


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## HertzHound (Jan 22, 2019)

joebeadg said:


> OK, I think I know what the NEC means, but does not clearly explain. They want the conductor sized to the lowest temp rating of any termination. So, if on one end of a conductor the terminal has a 75c rating, but on the other end it terminates on a lug with a 60c rating, you must size the conductor based on the 60c comumn. What do you think?


That’s it.


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## Incognito (Apr 14, 2019)

HertzHound said:


> .
> 
> Does your rule somehow let you put #12 RW90 on a 30amp breaker when you have 15 current carrying conductors in a conduit and both ends have 1.2 meters of wire?


No. We have to derate more than 3 current carrying conductors in a raceway. 15 would be 70%.

We also have a code that limits us to a 20 amp overcurrent on 12 awg wires in most situations. motors would be one of the exceptions.


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