A larger wiring device (50A) is not marked on the device with the termination temperature. However, upon consulting the manufacturer, they stated it is rated for 60 and 75 degree C. Does this comply with 110.C.1.a.3.... "Conductors with higher temperature rating ratings if the equipment is listed and identified for use with such conductors" to allow the use of the 75 degree column of table 310.15.B.16.
wiring device termination temperature
- Thread starter mjmike
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Carultch
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The NEC does specify "listed and marked otherwise". This means to me, that if it isn't factory labeled, it is rated for the default 60C.
FYI, the purpose of "dual rating" it for 60/75C, is that the 60C rating allows you to use 60C rated conductors and 60C sizing. If it is only rated for 75C, then you'd have to use at least 75C rated wiring, no matter what sizing strategy you use.
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From the UL Guide Information for "Receptacles for Plugs, and Attachment Plugs (RTRT)".
I read that as saying that if it is identified for use as 75 degrees then you can use both the 75 degree and 60 degree column. I'm not reading that as it say it must be marked on the device.
Here is an old thread I found where data had to have been gotten from the manufacturer.
http://forums.mikeholt.com/showthread.php?t=113096&highlight=termination+temperature
http://forums.mikeholt.com/showthread.php?t=113096&highlight=termination+temperature
jumper
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It says marked, identified is a different term, as the NEC says also "Unless the equipment is listed and marked other-
wise", so a strict interpretation means it has to stamped or such, but most inspectors will accept manufacturers data/info.
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And I read it at saying that if the device itself is not marked you are limited to the 60°C rating.
The NEC "listed and marked" is being used in a different context. It is saying to use the table for determining the ampacity unless it is listed and marked otherwise. It is not referring to the temperature where it denotes "listed and marked".
jumper
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Okay I am lost on what your exact question is.:?
Can a wiring device under 100A be wired with the conductor ampacity based on the 75 degree C column IF there are no markings on the device itself but the manufacturer's data states the terminations are rated for 75 degrees C?
jeremy.zinkofsky
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The NEC says "listed and marked" but an engineer would be comfortable trusting the manufacturer if they would put something in writing, for liability purposes. However, an inspector could still ding you if he were so inclined. Can the manufacturer point you to a UL listing? That would replace a marking.
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jumper
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AHJ/inspector call IMO. NEC does not specifically say such or have an exemption.
The one's I have dealt with would.
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If it is a listed device, it will be marked on the device. If there is no marking it is 60°C and use of 75°C ampacity gets a red tag from me no matter what the manufacturer says.
kwired
Electron manager
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I sort of see what you are saying here but if you use 60C ampacity table - you end up with larger conductor, some instances maybe the same but never smaller then you come up with using 75C ampacity table. kind of a technicality that doesn't really change end results.
Carultch
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What I'm saying, is that there is a difference between a device rated for 75C, and a device that is dual-rated for 60/75C.
The last page of this paper form Bussmann covers it in more detail:
http://www.cooperindustries.com/con...ary/BUS_Ele_Tech_Lib_Conductor_Ampacities.pdf
Like most applications related to the 60C column of 310.15(B)(16), this is more of an academic rule than a practical one, because most wire types are rated for 75C, if not for 90C, and therefore the lack of a dual rating of 60/75C is a rare issue.
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No.
jumper
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I cannot open it. Can you copy and paste the relevant part?
Carultch
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Termination Ratings
As discussed above, terminations have a temperature rating that must beobserved and this has implications on permissible conductor temperaturerating and ampacity. Shown below are three common termination ratings andthe rules. Remember, from the example above, the conductor ampacity mayalso have to be derated due to ambient, conduit fill or other reasons.
60°C:
Can use 60°C, 75°C, 90°C or higher temperaturerated conductor, but the ampacity of the conductormust be based as if conductor is rated 60°C.
75°C:
Can use 75°C, 90°C or higher temperature ratedconductor, but the ampacity of the conductor must bebased as if conductor is rated 75°C. A 60°Cconductor not permitted to be used.
60°C/75°C:
Dual temperature rated termination. Can use either60°C conductors at 60°C ampacity or 75°Cconductors at 75°C ampacity. If 90°C or higher temperaturerated conductor is used, the ampacity of theconductor must be based as if conductor is rated75°C.
kwired
Electron manager
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- NE Nebraska
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- EC
But conductor ampacity has most everything to do with rating of the insulation not the conductor itself. The terminal temp rating wont care what insulation is on the conductor, it cares how many circular mils of copper make up the conductor.
If you use 60C ampacity chart to select the conductor you get more circular mils of conductor then you will using the 75C chart for same ampacity level.
I really don't see the point of dual temp termination rating, or at least have not heard a good explanation of why such dual rating exists. 60/75C terminal can accept the heat produced by a conductor applied at 75 C rating, but if you apply a 60C conductor - it will be larger conductor for purpose of producing less heat because of the lower temp insulation rating. The general rules of 110.14 already are sufficient to not need to dual rate it IMO. If not marked the rules in 110.14 dictate temp rating, if marked the higher rating is acceptable if using higher rated conductor, no point in marking with lower rating.
All you quoted was essentially device instructions, nothing that tells us why the 60/75C terminal rating exists.
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