table 310.16

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J

jbfan74

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Newnan Ga
#8 THHN/THWN-2 is rated at 55 amps. When connecting to a 75 degree breaker, is it then rated for 50 amps? Also, I can not find a temp. rating on the recepticale that this is connecting to. It will be a hubbell # CS8269, 50 amp, 250v twistlock. Should I forget trying to use #8 and use #6?
 
Re: table 310.16

If your under 100 amps, I would use the 60 c rating, unless you can find out the rating of the receptacle.
 
Re: table 310.16

I received a call from my supplier who stated the manufactor said the terminals were rated at 90 degree, same as the wire. Since this is right on the border line I think I will go with the #6.
 
Re: table 310.16

I received a call from my supplier who stated the manufacture said the terminals were rated at 90 degree,
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I don't believe it. I'd have to see that on the manufacture's spec sheet and UL listing before I would accept that the receptacle terminations are rated for use with the 90C ampacities.
Don
 
Re: table 310.16

A large computer array. It has 2 50 amp lines, feeding internal ups and then whatever goes on inside the thing! It can run on one circuit, but the design of the thing allows 2 circuits from different sources. Since this is the testing area I do not have to worry about the different sources, coming from the same panel.
 
Re: table 310.16

JB
If the load is not continous and 50 amps or less
why not use the #8 thhn? It is rated 50 amps at 75C. Will the total load exceed 50 amps if one of the sources goes out?
 
Re: table 310.16

That was my question. If the recepticale has no temp. rating, would I be able to use 75C? The power supplies are redundant. The system uses one power supply at a time, so it will never pull more than 50a.
 
Re: table 310.16

That was my question. If the recepticale has no temp. rating, would I be able to use 75C? The power supplies are redundant. The system uses one power supply at a time, so it will never pull more than 50a.
Click to expand...
No. 110.14(C)(1)(3)
 
Re: table 310.16

I looked at the data sheet link posted by Bob (rbalex) and have a question: In the row labeled "Operating Temperatures" it says, "Maximum Continuous 75 C Minimum -40 C (w/o impact)." Is this referring to the ambient temperature limitations of the termination and does not have anything to do with the 75 deg C temperature rating we are talking about here?

Also, in the row labeled "Temperature Rise" it says, "Max 30C temperature rise at full rated current after 50 cycles of overload at 150% of rated current at a power factor of .75." Does this mean that it is rated to accept 30 deg C temperature rise from a conductor connected to the terminals? And that this temperature rise would happen only if a conductor installed has the proper ampacity? :confused:
 
Re: table 310.16

JB
Don is correct in his post but that does not mean that #6 is ok. You need to determine the temp rating of the 250v twistlock. The page Bob put up does not say what the temp rating is.
 
Re: table 310.16

jb
In the cut sheet Bob posted it had this information:
Temperature Rise:Max 30C temperature rise at full rated current after 50 cycles of overload at 150% of rated current at a power factor of .75.
Does this mean max temp is 30C rather than 60C?
I do not know. Think you should check just in case.
 
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