mgookin
Senior Member
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- Fort Myers, FL
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- Retired inspector, plans examiner & building official
If OP is an engineer working for a manufacturer, he has to get it right. It's not just "go get a bigger cord."
Ampacity of a computer/printer power supply cord
- Thread starter Codified
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- Placerville, CA, USA
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- Retired PV System Designer
:thumbsup:]
And, reasonably enough, the manufacturer of a consumer computer product cord for a power brick is going to expect it to be used at human-comfortable temperatures. For higher ambient than that, the temperature correction tables should work just fine.
And, of course the power brick rating may come into question too at that point.
kwired
Electron manager
- Location
- NE Nebraska
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- EC
If we are manufacturing a consumer product we are probably more concerned with listing issues then what the NEC says about ampacity of this cord.
SceneryDriver
Senior Member
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- NJ
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- Electrical and Automation Designer
Fair point. I read the OP's post as someone who was responsible for installing said equipment in the field, apparently in a warm location.
SceneryDriver
Codified
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- Orange County, CA
Somehow, email notifications for the additional/recent replies to my post had ceased. After collecting considerable input on the topic, from here and beyond, it seems to sum up something like this: For installations that are required to comply with the NEC, Article 400 applies to Type 'SJT', 'SVT' (and similar Thermoplastic & Thermoset type) power cords, and it puts the ampacity at 10A for a 30C ambient (for 2 current-carrying conductors). However, temperature correction was not included for the SJT & SVT cords (and many other types) until the 2014 edition. This can be seen by comparing the 1st tables of 400.5 in the last 7 editions, or so. Oddly, for many other types of cords (e.g., those listed in the 2nd table of 400.5, such as Types 'SC' & 'PPE'), the NEC added temperature-correction requirements for these particular cords starting with the 2005 edition (but not to those of the 1st table).
Although the 2014 NEC now seems clear regarding temperature correction requirements for the cord Types SJT, SVT, etc., that was not the case prior to the 2014 Code. Of particular interest is that although these cords are comparably as easy to install as common extension cords (i.e., no tools required), they are often not installed for 'temporary' use, and the typical installer likely lacks sufficient knowledge of NEC temperature-correction requirements.
Although the 2014 NEC now seems clear regarding temperature correction requirements for the cord Types SJT, SVT, etc., that was not the case prior to the 2014 Code. Of particular interest is that although these cords are comparably as easy to install as common extension cords (i.e., no tools required), they are often not installed for 'temporary' use, and the typical installer likely lacks sufficient knowledge of NEC temperature-correction requirements.
petersonra
Senior Member
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- Northern illinois
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- engineer
I think you are making an assumption that in some way that a cord that is part of a listed device has to in addition meet some kind of NEC requirements and you are obsessing over the cord.
I am just not sure that is in fact true that anything part of a listed assembly requires anything other than the UL or other NRTL sticker.
The instructions that came with the printer will tell you what ambient temperature limits are suitable for the device. If the ambient temperature exceeds those limits you would be violating the instructions and thus could not install it there regardless of the cord issue.
I am just not sure that is in fact true that anything part of a listed assembly requires anything other than the UL or other NRTL sticker.
The instructions that came with the printer will tell you what ambient temperature limits are suitable for the device. If the ambient temperature exceeds those limits you would be violating the instructions and thus could not install it there regardless of the cord issue.
fmtjfw
Senior Member
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- Fairmont, WV, USA
There are higher temperature versions of cords and Cxx connectors. Google "wiki iec c13" C15/16 120?C 10A; C15A/16A 155?C 10A.
Codified
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- Orange County, CA
Bob, your point is well taken. However, once cords enter desk drawers & boxes filled with other IEC connector cords, their association with any particular Listed assembly that they may have originally been packaged with is likely lost. But that is separate from my original question, which had more to do with how an installer (let's say a skilled & knowledgeable electrician) would have been expected to know if such a cord would have sufficient ampacity for a high-ambient environment (say 40C). For installations falling under the 2014 NEC, this determination now seems straight-forward.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
It still has little if anything to do with the NEC, regardless of the skill level of the installer.
IMO, if listed equipment is installed in an area where the ambient temperature is within the listed devices specifications, it is acceptable. If the ambient temperature exceeds the limits imposed by the device's instructions, it cannot be installed there at all.
Codified
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- Orange County, CA
fmtjfw, the cords & connectors you mentioned would suffice for higher-temperature applications. But they all have the same base ampacities, and the same temperature-correction factors. Thus, their temperature-corrected ampacities (starting with the 2014 NEC) would be no more than the Type SJT cords that have lower temperature ratings
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