What temperature to use for cable de-rating for design used in multiple locations

[Pitt123]

I am doing a small design for a plug-and-play type system that can be used in several locations around the country, and can be integrated into any system with small modifications.

When sizing my cables I ususally use the temperature of the area of installation for de-rating the cables as necessary. But for such a design where it may be installed inseveral locations around the country what temperature would you use to account for de-rating? I know the temp may vary from location to location but is there a good temp to use as a design basis?

 

[rbalex]

Is the common application outdoor or indoor in conditioned space? If outdoor, you may as well use the hottest location you can find.

 

[Pitt123]

Is the common application outdoor or indoor in conditioned space? If outdoor, you may as well use the hottest location you can find.

It is for an outdoor location. This may be installed country wide so would you suggest choosing the hottest location in the country?

 

[rbalex]

It is for an outdoor location. This may be installed country wide so would you suggest choosing the hottest location in the country?

Unless you want to redesign it for each location. Certainly the hottest location it would likely be installed. Check ASHRAE's Fundamentals for the recommended design temps.

 

[petersonra]

I would keep in mind that the design standards on this kind of stuff for a listed product sold as a listed product are radically different than for stuff that abides by the NEC.

 

[weressl]

I am doing a small design for a plug-and-play type system that can be used in several locations around the country, and can be integrated into any system with small modifications.

When sizing my cables I ususally use the temperature of the area of installation for de-rating the cables as necessary. But for such a design where it may be installed inseveral locations around the country what temperature would you use to account for de-rating? I know the temp may vary from location to location but is there a good temp to use as a design basis?

40 Centigrades is used in the US as the normative high temperature. (That's one of the reasons why electrical equipement normally bears teh design temperature reference of 40C.)

 

[David Nelson]

Design temp

Design temp

If you haven't done so already the ASHRAE Table indicates a 2% design temp. of 111deg for Palm Springs. That's the high on the table.
The 40dg C. table is only 104 F, you might consider using the ASHRAE standard instead. (more conservative)

 

[weressl]

If you haven't done so already the ASHRAE Table indicates a 2% design temp. of 111deg for Palm Springs. That's the high on the table.
The 40dg C. table is only 104 F, you might consider using the ASHRAE standard instead. (more conservative)

That may be technically correct, but if it is not in the NEC, it does not qualifies as a valid calculation. Of course you can ignore all and go ahead with the engineered systems but make sure all your calc's are on hand forever when OSHA comes around and attempts to cite you for non-compliance - and of course there is the ever-pesky AHJ hurdle you have to pass first.:happyno: