Installing romex in EMT conduit

[roger]

Mike holt also has a video on this

And you misunderstood what the video is saying. When posting here on the forums you need to have your code book with you, that way you can follow what the others are telling or asking you.

 

[Jpflex]

And you misunderstood what the video is saying. When posting here on the forums you need to have your code book with you, that way you can follow what the others are telling or asking you.

Like I said my code book is at work, I do not carry it around with me everywhere I go and on my days off

 

[roger]

Like I said my code book is at work, I do not carry it around with me everywhere I go and on my days off

I wouldn't expect you to carry it everywhere but when you make statements or someone points you to an answer here on the forums you should have it to reference.

 

[electrofelon]

But nec says you cannot terminate a conductor with a higher temperature rating than the temperature rating of the point or component of termination unless for cases of ampacity adjustment derating on the conductor

Think about that for a minute...that would make absolutely no sense.

 

[ActionDave]

By the same logic you could not use wire with 600V insulation on 480V circuits.

 

[wwhitney]

Like I said my code book is at work, I do not carry it around with me everywhere I go and on my days off

If Victorville is Victorville, CA, you can read the NEC as adopted and modified by CA here. This is the 2022 CA Electrical Code, based on the 2020 NEC, which doesn't go into force until January 1, 2023, I believe:

California Electrical Code 2022 based on the NFPA 70, 2020

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

You can also read it at nfpa.org with a free account, but their interface is intentionally less user friendly.

Cheers, Wayne

 

[Jpflex]

If Victorville is Victorville, CA, you can read the NEC as adopted and modified by CA here. This is the 2022 CA Electrical Code, based on the 2020 NEC, which doesn't go into force until January 1, 2023, I believe:

California Electrical Code 2022 based on the NFPA 70, 2020

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

You can also read it at nfpa.org with a free account, but their interface is intentionally less user friendly.

Cheers, Wayne

O I see ok so nec 2022 is not effective until Jan 2023 California. So by reading this code book I’ll be ahead

 

[Jpflex]

Think about that for a minute...that would make absolutely no sense.

 

[Jpflex]

Your not understanding as the statement makes perfect sense. I’ll try to explain it another way. If the conductor is rated 90 degrees Celsius and you are terminating on a breaker rated 60 degrees Celsius, mr. mike holt said this could not be done unless the wire is deranged to the ampacity of the wire conductor of the 60 degree rating.

 

[wwhitney]

But there's an important difference in emphasis: more commonly you'd say "when a 90C rated conductor is terminated on a 60C rated terminal, you are limited to the 60C termination temperature ampacity." "You are limited to" is the same as "you can't do it unless." The latter is just discordant as it suggests that normally you can't do it, when it's done all the time.

Cheers, Wayne

 

[Jpflex]

But there's an important difference in emphasis: more commonly you'd say "when a 90C rated conductor is terminated on a 60C rated terminal, you are limited to the 60C termination temperature ampacity." "You are limited to" is the same as "you can't do it unless." The latter is just discordant as it suggests that normally you can't do it, when it's done all the time.

Cheers, Wayne

So the breaker rating determines if said conductor can be used since breaker ultimately reduces or limits ampacity?

 

[wwhitney]

So the breaker rating determines if said conductor can be used since breaker ultimately reduces or limits ampacity?

No. The breaker temperature rating is a limit on the final circuit ampacity. Nearly all the conductors you ever use have 90C insulation these days, and it's never a problem to have a conductor insulation temperature rating higher than the minimum required.

Cheers, Wayne

 

[Jpflex]

Or are you saying it can be done in disregard of code or is done often?

 

[wwhitney]

Simple example: 20A breaker supplying a duplex NEMA 5-15 receptacle, 30C ambient temperature, just 2 CCCs. What wire size do we use? For copper it needs to be #12 minimum due to 240.4(D). Say the breaker has 75C rated terminals, but the receptacle terminals are only rated 60C (not sure, I've never checked on a NEMA 5-15).

Do we need to use an insulation type with a temperature limit of 60C? No, we can use a wire type with 90C rated insulation, we just don't gain any advantage to the 90C rating on the conductor. The circuit ampacity ends up limited to the 60C rating of the receptacle, or 20A. If we had some old 60C rated wire type, we could use it up here.

More complicated example: Now say we had 4CCCs because the circuit shares a conduit with another 2-wire circuit. Could we use 60C insulation? No, that would be a violation, as the 60C ampacity of #12 is 20A, and after the 80% adjustment for 4 CCCs, we are down to 16A, and 240.4(B) doesn't apply to a circuit supplying multiple receptacles.

But we can use #12 Cu with 75C or higher rated insulation. Because then for the derating, we can start at the 25A 75C ampacity, which after the 80% factor gives us an ampacity of at least 20A.

Cheers, Wayne

 

[roger]

So the breaker rating determines if said conductor can be used since breaker ultimately reduces or limits ampacity?

No, the lowest temp rating in the chain be it the termination, splice, breaker, receptacle, switch, conductor, etc... determines the maximum all can be used at. If one component is 60 deg everything else in the chain can be 90 deg rated but they can not exceed 60 deg

As I said and earlier and the others have tried to point out, you really need to look at the video and literature again, you are not grasping is being said.

 

[roger]

Or are you saying it can be done in disregard of code or is done often?

Nobody has said or implicated that.

 

[winnie]

Your not understanding as the statement makes perfect sense. I’ll try to explain it another way. If the conductor is rated 90 degrees Celsius and you are terminating on a breaker rated 60 degrees Celsius, mr. mike holt said this could not be done unless the wire is deranged to the ampacity of the wire conductor of the 60 degree rating.

I think you are saying the same thing as the rest of us, just in a different way that is somewhat confusing.

The temperature ratings are _maximum limits_, not requirements. A 60C termination is limited to operating at 60C or less. A 90C wire is limited to operating at 90C or less. A 90C conductor will safely function at a 60C operating temperature because 60 is less than 90.

So if you have a 90C wire in contact with a 60C termination, you are limited to operating with a conductor current which will result in at most 60C operation at the location of the termination. The 60C termination requirement sets the maximum current you are permitted to run in the conductor, and the 90C wire is perfectly happy running at 60C. This isn't 'derating'; this is selecting the temperature limit for all components involved in the circuit at that location.

If you have 90C wire in a conduit with a 60C temperature limit, then again you are limited to the 60C ampacity because your conductor temperature must be limited by the most restrictive component in that location.

-Jon

 

[wwhitney]

No, the lowest temp rating in the chain be it the termination, splice, breaker, receptacle, switch, conductor, etc... determines the maximum all can be used at. If one component is 60 deg everything else in the chain can be 90 deg rated but they can not exceed 60 deg

That's not quite correct. Take the two examples I gave. In the second example, with 4 CCCs, the conductor temperature at that location might exceed 60C. That's why it would need to have at least 75C rated insulation.

Cheers, Wayne

 

[Jpflex]

No. The breaker temperature rating is a limit on the final circuit ampacity. Nearly all the conductors you ever use have 90C insulation these days, and it's never a problem to have a conductor insulation temperature rating higher than the minimum required.

Cheers, Wayne

That’s what I was thinking but mike holt has made more confusion on this

 

[roger]

That's not quite correct. Take the two examples I gave. In the second example, with 4 CCCs, the conductor temperature at that location might exceed 60C. That's why it would need to have at least 75C rated insulation.

Cheers, Wayne

Wayne, that is not what is confusing the OP and thanks for making it more confusing for him.

Here is what started this

The company I work for only buys THHN but according to code this 75 degree wire is too high for typical installations? Such as terminating on standard 15 to 20 ampere receptacles? Even with ampere derating, what kind of wires should be bought for 60 degrees?

Sometimes simple to the point answers are the best.